Opening Chokes

[William Davis]

Here is a question for the experienced. Am not a gunsmith or machinist, do have a lathe and have been a hobby gunsmith for a long time. Looking at many SxS shotguns have seen mostly very poor opened choke jobs, you can spot them right away.

Way I have always done deep hole drilling is drill the hole first then turn down the outside to make the finished job concentric. Never filed a shot gun barrel but my guess is the inside bore work choking and polishing was done before the barrels were filled outside. If not to finished at least the majority of inside work was done before the outside was filed.

When the outside was filed the gunsmith finished muzzles up to have a minimum thickness. No doubt if he needed to take more weight out of the barrel he did it away from the muzzle. Mark of a factory choke is plenty of metal at the muzzle everything concentric no thin or thick sides.

100 years later open up a choke result is a very thin wall thickness at the muzzle. And if opening up it takes a very good workman to keep the finished job concentric. Working by hand with a reamer I doubt if there is a 10 % chance of the finished job coming out looking like a factory muzzle. Chucked up in a lathe everything carefully set up perhaps the chances are better, still it takes a very good man to keep things centered when right or wrong is couple of thousandths you can spot with your eye.

Am I missing something or is my theory that open jobs go wrong more that right correct. Are there gunsmith that can alter chokes that can’t be spotted from factory? Might be I never spotted good open jobs because they were good.

I get open patterns with Spreader loads, just thinking about how open jobs are done, don't plan to have it done to any of my guns.

William

[Dean Romig]

Am I missing something or is my theory that open jobs go wrong more that right correct. Are there gunsmith that can alter chokes that can’t be spotted from factory? William


1. Yes

2. Yes

Th chokes were cut from the rear using the bore to center the cutter. Parker Bros. chokes are sometimes 5" to 6" long but generally around 3". There is often a parallel section at the muzzles that measure as much as 3/8" long.
There are a few smiths who can properly cut chokes. Mike Orlen in Amherst, MA, Abe Chaber in CT, and Kirk Merrington in TX come to mind.

[William Davis]

Even if good work much opening at all the gun is still going to end up with thin metal at the muzzles. Clear flag it's been altered.

William

[Bill Murphy]

There is no one that knows so much about what they are doing in the "opening chokes" business that I would trust a medium high condition 12 gauge Trojan to their skills. This has worked for me in fifty years of shotgun gunsmithing experience. There are too many horror stories out there. I just don't do it.

[charlie cleveland]

bill if it worked for you for 50 years it should work for another 50 easy..good advice for sure....charlie

[Paul Harm]

There are many smiths who can open chokes correctly - Brad Bachelder comes to mind. I open my own, but then I don't have to satisfy anyone but myself. And I am satisfied.

[Paul Harm]

William, first one has to check barrel thickness at the muzzles before opening the chokes. I've found the American made doubles I've checked all have thick walls. English doubles are a different story. If you're going to open a gun with .035 constriction [ full choke ] to say .015 [ I/C ] you're removing .020, or .010 on a side. The guns I've done for myself all had at least .040 to .060 wall thickness, so removing .010 isn't going to hurt a thing. The Americans seem to like heavier guns, where as the English like light guns, meaning thinner barrels. But then we also like heavier loads of shot. I guess it's just our nature, bigger is better, too much is just right.

[Richard Flanders]

I have to side with Bill on this one from my experience. I can certainly tell you of a very well know smith who apparently CAN'T do it properly and left me with a set of non-concentric chokes with as little as .017" on one muzzle and a +.004" blunderbuss choke on the right barrel... this on a very very nice transition era 26" SG VH12. Makes me embarrassed and sick every time I look at it and degraded the gun's value dramatically.

[Bruce Day]

Some years back I was asked to look at a Parker 16 ga that was missing many targets that seemed to be centered. The first thing we did was get out a patterning board, and found both barrels shooting laterally elongated patterns without much high or low. The muzzles bore that out, thin and oblong. The chokes had been opened by an unknown gunsmith to .006 or so, and there was not enough barrel wall thickness left at the muzzle to bore them again to round.

So the lesson is I suppose to be very careful, have enough wall thickness, ream them out gently, or better yet, leave them alone, use spreader loads, or just shoot for the head.

A reloader can get a greater spread by not using a shot cup, just an over powder wad. Or an even greater spread by a true spreader post and wad combination.

Keep in mind that the difference in a killing circle on a pattern board (30" at 40 yards) between full and cylinder is a 6" radius. So chokes give you inches in killing effectiveness whereas misses are usually much greater than that. Doing shotgun instruction, you look over the shoulder at the shot pattern by the clay and see misses by three feet or more. That is for an effective killing circle on game, generally six or more pellets on a game bird silhouette in the 30 inch circle. If you are shooting clays, one or two pellets is all it takes to break it. So, when you are considering chokes, keep in mind there is a difference between a clays effective choke and the tighter choke necessary for an effective and humane kill on a game bird.

[Dean Romig]

Very well stated Bruce.

[William Davis]

This scanned photo shows what it takes to do good work inside a double barrel. First photograph I have seen of a proper rig. I doubt if half a dozen gunsmith in the US are equipped as well.

http://i492.photobucket.com/albums/rr287/pontoon225/Barrel%20Hone%20Rig_zpstph5bafd.jpg (http://s492.photobucket.com/user/pontoon225/media/Barrel%20Hone%20Rig_zpstph5bafd.jpg.html)

Caption says it's set up for honing but no doubt used for all inside work. Key is the barrels are supported in a sliding table. Speculating, they are indicated inside muzzle and breech for true. Looks like the reamer shaft is bushed and can be extended past the muzzles were it can be indicated again for true . You could ream from the breech end but if so I can't figure how you could check it for run out. Perhaps the reamer has a hole in the end large enough for a dial indicator probe that can be reached from the muzzle.

Big difference from slipping a tapered bushing inside and cut by hand using a tap wrench.

William

[Paul Harm]

I've had pretty good luck, but then I'm cleaning the bore and checking what I did after every other pass. I bought a 1894 Remington F grade " trap gun " for a good price because the right barrel was only IC choke. By jug choking it I took it to a Mod. But that takes quite a bit longer because the reamer is put to the proper place then adjusted tight against the barrel, reamed, adjusted back down so it can be removed and cleaned. Then clean the bore of cutting oil so the mic can be used without gumming it up with oil. Because the reamer is in the barrel when adjusted tight you can only get a thou or two. Takes awhile, but if there's enough wall thickness, choke can be put back in.

[William Davis]

Paul It can be done by hand if careful. I opened up a 870 barrel years ago and working with a "Armorer" not a gunsmith, cut and threaded another 870 for screw in chokes. Single barrels easier to work with and pump guns have right much metal in the barrel.

Price of a mistake on a 870 is 100 bucks though. Plenty of used barrels for sale.

William

[James L. Martin]

After 50 years of shotgunning I have come to the realize that opening chokes is almost never the answer ,you will not shoot better and you can ruin a good shotgun , also I will never install after market choke tubes in any shotgun. Take the time to pattern your gun with different shells like spreader loads, low cost target loads, high end target loads etc. It may really surprise you, the best factory spreader loads for me were polywad brand , which I use in a 20ga VH with full chokes [.025 ] for woodcock hunting. I hate to see those 100 year old factory chokes removed for no good reason. I now just pass on any gun that has altered chokes or Brileys .

[allan.mclane]

I just spent the afternoon patterning a 16ga Trojan with 26" bbls that has chokes that measure Modified and Full. Using a variety of loads, all with #8's, the Mod barrel throws between 48% and 88% and the Full side throws between 56% and 92%. Plenty of variation is available to those willing to study their gun's performance.

[Bill Murphy]

Regarding opening chokes for clay targets, my stock answer, directed at no one in particular, is "Learn to shoot.". If a gun shoots too tight for close game birds, my stock answer is "Use another gun.".

[Paul Harm]

William, I believe the chokes were the last thing done to a barrel, and with a double, after the tubes were soldered together and finished. Usually a reamer is used from the breech end with guides on the rod to keep it centered. If most of your shooting is under 30 yards such as grouse hunting or clay games then you'd want a skeet or I/C choke so you wouldn't be destroying the game bird or over handicapping yourself with clay birds. I don't hunt anymore, but love to shoot clays, and like it even more when I beat my friends. We shoot three times a week about four to eight boxes each day. Just about all the shots are under 30 yards and for this reason I've opened the chokes on most my guns. My SxS trap gun has Mod and IM, the rest anywhere from skeet to LM. Todd Bender, a famous skeet shooter uses skeet chokes and no one is telling him to use tight chokes and just " learn how to shoot ". If I were mainly a hunter, then I'd leave the chokes alone and use spreader wads when needed. But I'm a clay target shooter and have my guns choked for the game I'm shooting. I'm not telling anyone to open their chokes, but there are good reasons for doing it if one so desires.

[Paul D Narlesky]

Hello All,It has been awhile. Very interesting thread for me as I am on the fence about a DH 12 on a #1 frame 28 bbl wall thickness at muzzle on one bbl is about .040 the other a bit less .032 or so the store selling can't accurately measure the inside bores and has a no return policy on old guns. the price is favorable but I am nervous about those chokes being opened to IC and IM (that is with a quick check brass gage) I did the best I could to measure the walls in 4 or 5 places. I am wanting the gun but have no good way to check the bore size past the chokes properly..Thanks & Best,Paul

[Richard Flanders]

A nice 28"? #1frame DH12 for a reasonable price would have to have some serious warts to prevent me from begging or buying whatever tool I needed to check the barrels and chokes out. Your brass choke gauge isn't adequate. You can get a relatively inexpensive Enco inside finger dial caliper that will reach I think 3.5" into a barrel and is good to +/-.001". It's what I use for most choke measurement and have found it to work on most Parkers. Are the barrels really 28" and if so, have they been cut? I have a v nice #1 frame 26" damascus GHE12 that only weighs 6#10oz and carries like a 16ga and is a great grouse/woodcock gun. The bbls have been cut and the chokes are open but it papers that way from the factory.

[Ed Blake]

The rule of thumb is opening chokes will give you about 2" in pattern diameter per choke designation. Misses are measured in feet. Learning to shoot well with full chokes builds confidence.

[Paul Harm]

Paul, a inside mic used for measuring shotgun bores that reach in about 18" can be bought from Brownells for about a 100$. Ed, when we get new shooters on the skeet field we don't try to handicap them with tight chokes but want them to use the proper chokes for the game they're shooting. Not hitting anything, or a lot of misses is very discouraging. It's a whole lot more fun to hit some targets. I've had friends who are quite good forget to change chokes and miss a lot of birds and then half way through realize they have full chokes installed. If what you've said about 2" per choke is true then there's about a 10" bigger pattern when going from full to skeet chokes and 12" if a cyl bore is used. That's quite a bit. There's a reason for different chokes. Back when most our old doubles were made they were choked full for hunting, and even that was too much for Pat or Woodcock hunting. Even pheasant hunting over pointing dogs a mod coke would be more than enough. On our SC's course, most birds are under 35yds and shooting skeet chokes will break them nice. All my SxS's at the most have LM, many SK. I have one that's LM/IM for trap. I have a friend that shoots a Lever with cut barrels having no choke and has shot a 44/50 on SC's. The choke rating was for back when fiber wads were shot, and now with plastic wads about one increase in choke is realized. I believe too many guns are passed up because someone worries the chokes have been opened up. Unless you're aduck hunter, it doesn't really matter IMHO.

[William Davis]

Thing about tight chokes is you can cut the shot load and still get good pattern density. Open chokes need more pellets, I get around it by using small shotl for close targets in open choked guns=more pellets in the load.

Of course wider the pattern more birds you are going to break. Couple of clays courses around here open chokes would be a handicap, High percentage of real long shots, few short ones it has Spreaders work well. One course we shoot no doubt it's an advantage to have a open gun. On it hot shot O/U shooters use Skeet and Skeet mostly. I have both open and tight guns different tools for different jobs.

William

[Paul Harm]

There's been a couple of articles on the patterns of 3/4oz loads in the 12ga. I haven't tested, but they claim the patterns are too tight at normal skeet ranges [ 22 yds ] and fiber wads should be used to open them up a bit. Maybe that's why I get good hits out to 45 yds or so with skeet chokes using plastic wads.

[William Davis]

Paul

3/4 oz still patterns very tight in a full choked gun not as dense as you would like if long shots. I shot a round of 5 stand with my 30 inch GH Full and Mod yesterday with 3/4 oz # 9's, & hit a couple of 35 & 45 yard clays. If 3/4 oz can't afford large shot, very few 7 1/2's in 3/4 oz plenty of # 9's trade off is small shot runs out of gas at distance. 45 is really streaching it. 25 no problem 35 long side of OK however it broke every 35 bird I shot at= 3 or 4 It only broke one of the 45's . Most of our club 5 stand shots are 25-35 yards. Couple of 15-20's too and missed a good half of them.

Mostly I use 3/4 # 9 on the Skeet range in a VHE 26 inch I/C and about Mod were it holds it's own with dedicated Skeet guns. 7/8 # 7 1/2 is my standard clays load for the longer tighter guns & longer shots.

Having said that am ordering some # 7 shot, will load up 1 oz loads for real long range 12 G, 1 1/8 for long 10 G shells. Pattern at 35 45 & 55 see what they look like

William

[Paul D Narlesky]

Definitely opinions both ways. I ended up buying the DHE #1 frame gun it all checks to pretty well and is true to serial # book. The gun has a 16" LOP to front trigger along with honest wear but not abuse. I was able to go to MW Reynolds here in town and he was happy to check the bores correctly and the chokes. the right barrel has had some honing done and the wall thickness was taken down a bit about .005 in that area. about 6-8 in back from the muzzle. We don't think that will be and issue. I am going to get a letter and see if that long LOP has a story. I will try to get a couple pics up soon but it has been awhile so please be patient with me. Thanks & Best, Paul
PS Moderator feel free to move the post

[Daniel G Rainey]

Great discussion on opening chokes. When I consider buying a gun, how it is choked, is of great importance. It must be choked for the game you intend to shoot with it. then I consider gun fit. One the great features of side by sides with double triggers ( if the barrels are choked differently and most are ) is the option of pulling the trigger of the choke you need. recently, I hunted birds in Vermont with someone who right barrel was choked Mod. and he used Spreader loads in the right barrel and regular loads in the left. It worked for him.

[Bill Murphy]

Paul Narlesky, we would like to see the letter on your interesting D Grade.

[Bill Murphy]

It has always been interesting to see the large number of Parkers that were factory bored cylinder and full. I find that to be a great all around combination for general bird hunting. If the first bird is commonly a pheasant or a longer shot than a normal cylinder bore shot, load the cylinder barrel with heavy loads.

[Paul Harm]

Paul, it sounds like maybe someone " jug choked " the barrel. I've done it a couple of times to put some choke back in a gun but because it's so time consuming I do it only for myself. Back in the day ol V.M. Starr use to win turkey shoots with his muzzleloader against those new breechloaders. He used a cyl. bore gun jug choked to extra full - a lot of guys wouldn't shoot if he showed up. Have your gunsmith check the difference from the honed out area to the muzzle - that's your true choke.

[Scot Cardillo]

Hadn’t seen this thread but have one touching upon this very subject in the Reproduction section.

Speaking for myself, I’m still on the fence about opening up a choke on a 'spare' set of barrels. Although I cannot stand reloading, just might do myself some learning using fiber wads etc as this is where I just do not possess fundamental experience in manipulating patterns.

If you care to read my ramblings, here’s a long winded post on the subject of opening chokes ~ proper.

—

The photo of that suave fella w/a set of barrels mounted in a Cylindrical Grinder is about as good a setup as you’re going to find, by every measure it is the ‘right’ way to do it.

The benefits of using a cylindrical grinder are many.

First, the barrels are in an unrestrained condition and the grinding will result in perfectly round holes provided the barrel set has been afforded stabilization following join.

As is most often true in a machine shop, set-up is everything and often it is the most time consuming part of the process.

A good setup will have three key elements; Rigidity, repeatability, and geometric control.

I’m going to go out on a limb and proclaim that a perfectly round hole at the end of shotgun barrels (sxs ~ o/u) is rare.

There is likely to be some degree of oblong condition due to the rib. (unless ground as final finish in the manner as shown, including cigar of course).

A significant benefit of setting up on a cylindrical grinder for fine tuning is that the barrels can be fixtured or jigged proper so that they can be ground, removed, tested for pattern, and reinstalled precisely in the same exact location for more adjustment until the desired pattern and point of convergence is achieved. I would personally jig the fixture but that’s a whole different subject entirely. (Jigging would ensure precision in follow up finishing steps.)

Another benefit to a set up such as this is the fact that the holding fixture can be adjusted very easily in order to grind a directional change about the axis in any direction if poi is off at the desired distance. If poi is off on one barrel set, it is a simple matter of trigging out the adjustment required, adjusting the fixture, and grinding..this sort of setup facilitates that very easily.

Of course you have to have the material to grind away in order to do so. Can you say..way to go Mr. Skeuse on those uber full chokes :)

The only downside to the use of a cylindrical grinder is the fact that the resultant grain flow as finished would be perpendicular to the axis & in theory, that’s not ‘correct’. (Broaching would literally be the only way around this however that's just not feasible)

Although this is fact, this could be remedied quite easily with a quick swipe or two while barrels are in hand over some crocus cloth or lapping compound applied to a sufficiently long expanding mandrel made out of oil impregnated bronze (oilite)

The extension shaft being relatively close to the bore size & working from the breech end of course..although a bit overkill..this would be the exact sort of customized tooling found on the shop floor so the barrel finishers can do their thing.

Experienced hands would do this well and this is the exact sort of thing that is being lost to the ages, sadly.


—

Hand reaming:

Barrel sets are likely being jacked up for one of two reasons.

First..if the reaming is done from the muzzle end..run and run fast as this will destroy your barrel, I think this is generally understood and doesn't warrant a horse whipping.

The right way to ream proper is what has been alluded to already with one important caveat.

First and foremost, I personally would use an adjustable reamer and I would creep into my final dimension while also patterning.

The reamer should be inserted from the breech and the extension shaft should be a good slip fit into some machined for size bronze bushings which are closely fitted to the inside bore diameter along the axis. (About a .002 slip fit and bushing length of about 1.25 would be just about right)

Here is where a lot of folks go wrong..the last 10-12” of the extension just behind the cutter should NOT BE SUPPORTED by bushing. Let the reamer follow the hole that’s already there.

Think path of least resistance..the reamer is going to want to follow the existing hole but if it is too rigid up near the cutter..the extension/shaft is working against you and wedging against one of the chokes side walls ..if it’s too rigid it is more likely to cut unevenly and result in a finished hole that lacks concentricity to the outside diameter. Let the reamer float, within reason.

Always use at least a four flute reamer so that each cutter is properly supported during the cut..always.

Use a goodly amount of cutting oil - not WD-40 for goodness sakes

(Cool Tool is a good steel cutting oil)

Go slow and steady in a single forward cutting action start to finish, if you stop rotation, do not reverse direction because you want that initial bite to maintain its bite throughout the entire cut..let the tool cut and do not push it. If you take several ‘bites’ w/the reamer - this action will imprint itself into the final finish leaving little pock marks behind.

This may seem a bit overkill, but as they say, the devil’s in the details & these are just the sort of things that separate the amateur from the skilled..this requires feel.

Here’s a tip..often a fresh cutter is just a shade too sharp & it will want to grab instead of cutting cleanly unless all cutters are in perfect alignment and uber sharp - when they are, it’s like butter and feels as such.

Although this is not the time to pinch pennies on cheap tooling, good tooling aint cheap so with that being said.

To take a keen edge off of non premium tooling, make up a mock pc or two and run the reamer through it before cutting the chokes while using plenty of oil..this will knock down the cutting edge just enough as to avoid vibration. It warrants mention..a reamers cutting edge is only at the leading edge just behind the lead in chamfer of the cutter..the rest of the material behind it is for support, nothing more (it’s not an end mill).

*As an aside since we’re talking reamers..if you ream a hole in a drill press/milling machine..run the reamer through at low speed & a higher feed rate than what you would think..nice and steady in one continuous cut all the way through. Once reamer is through the material, stop the press and extract the reamer back through the hole while the tool remains stationary, unlike a drill.

Even by hand this same rule applies, no spinning reamers back out.

For this application, take it a step further..once the reamer is passed through, do not pull it back through the freshly cut choke for extraction because it will leave witness marks from each cutter in the finish along the axis.

Do one of two things - either adjust the reamer to a size smaller than the choke bore & then back it out or remove it from the extension altogether. This is what I would do in order to maintain the size as last reamed making it easier to make further adjustments if necessary.

Did I mention cutting oil..as in lots of cutting oil..cutting oil be good.

If you have a choke that is not concentric to the o.d.…a reamer will not fix it, don’t bother trying unless using a cylindrical grinder. You could do your best to hone one side in hopes to regain concentricity but…good luck w/that.

A poor mans cylindrical grinder can be fashioned up by using a tool post grinder so long as you have the bed length on your lathe and a precise rigid method of securing the barrel(s).

When grinding, the axis of the bores must be fixtured perfectly perpendicular to the barrels breech face or positioned 'as found' geometrically on a set of barrels as already fitted, otherwise - they are toast.

Me thinks this is not for the garage mechanic unless thoroughly understood.

If one insists upon such an adventure..get yourself some cheap choke tubes & a threaded barrel to practice on first.

Whole lot cheaper than learning on a set of sxs barrels.

[Paul Harm]

All the gunsmiths I know don't use a grinder, and there are a couple of very good ones. They all use an adjustable reamer, and all of them have six flues. I've read that when Remington bought Parker Bros. the Parker gunsmiths were upset that Remington did the final choke work from the muzzle end where as Parker did it from the breech end. If so, who's to say chokes can't be reamed from the muzzle. The problem you run into is if a lot is removed the parallel section will be quite long - maybe up to 4 or 5 inches. It's the thought of some that any more than 3/4" or so will result in a bigger pattern but with a " hot core ", so a whole lot isn't gained. Then you'd have to remove some parallel from the breech end with a tapper. Only the pattern board would tell. But if you think about it, an adjustable reamer has a tapper to it, so it will naturally center itself and be concentric to the original bore. I do my work from the muzzle, so this thread got me to wondering if the finish work had any run out. In the six doubles I checked, I couldn't find more than .003 from side to side than up and down. One could go to the trouble of setting up a lathe, but I find it unnecessary. It would be a good idea if one wanted to move the point of impact. Just my thoughts and humble opinion.

[William Davis]

That's a good post and will print out and see if I can absorb it. I am a home shop machinist which is a whole different thing than somebody that knows what he is doing. If you see any gaps in my understanding please point them out.

My observation on opening chokes is the difficulty in setting up. When the guns were built rough barrels were wired together and spread apart with wedges while regulated for point of aim. Ribs laid when it was right. Regulated is simply bending the barrel and if so it's not likely the hole is straight. Setting up on the inside to ream is luck of the draw, how much did they have to bend to regulate and were did the barrel bend. Are you setting up before or after the bend.

Outside same thing, barrels rough then hand stuck for taper weight and finish. Is it likely the outside matches the inside ? not very likely. Last problem is the choke itself. My guess is the desired degree of choke was rough cut in the barrel blank, then hand lapped while testing the gun. One of the Parker trademarks is a long choke, all mine are about 5 inches long, if machine altered I can't see how the reamer can duplicate the long tapered choke, reamers don't taper unless ground to taper before the tool is used. Is that a problem ? probably not, but you are giving away the Parker signature chokes.

Last looking at rows of Parkers at a large nearby shop, picked over inventory no doubt, the opened chokes can be spotted with your eye, out of round. Get one that looks round look inside you can often see the short choke with reamer marks were it was opened last few inches not the full taper. No doubt about it altered chokes are obvious and reduce the guns selling price.

My take away is altering the choke is never a good thing to do, much better to buy a gun that is choked like you want than try to make a long tight Parker into something not intended by the Factory. Having said that I have had Pump gun
Chokes altered with good results. Not expensive guns, barrels factory made by machine, round inside and out before altering. And if one gets messed up cheap to buy another barrel.

William

[Scot Cardillo]

Paul

It’s conceivable that Remington had a nesting fixture made to position the barrels properly for choke work from the muzzle.

That said, it would HAVE to be done to a choke that has already been ground/cut relative to the bore/breech face just awaiting final size, otherwise how in the world would they know ‘where’ the chokes or the bores are?

It occurs to me that the water table would have to be datum “A” and the breech face of the barrel would be datum “B” leaving the chokes ‘somewhere’ relative to that, even if positioning of the chokes/bores required adjustment after the datums are established.

I can envision a couple ways to skin that cat so far as fixtures are concerned.

You mentioned that you’re doing choke mods from the muzzle & believe me, I’m not doubting that at all and I’m not doubting the integrity of your work whatsoever.

Respectfully though - how are you tramming the bore and how do you determine geometry relative to the breech face before mod?

—

William - don’t underestimate yourself, you are asking the right questions.

You are correct, any choke work is only going to result in a longer straight section unless a reamer is ground with proper geometry.

If I get serious about altering a choke, the very first thing I will do is cast the choke area so I can see just what it is I’m working with so far as choke geometry is concerned.

If I can steer you in one direction with respect to machining..it sounds funny but, forget the numbers..obviously size matters however within the world of professional machining & manufacturing, it’s all about geometry.

A perfectly sized choke doesn’t amount to anything if you don’t know where that hole is relative to the other functional elements, in this case..Datum “A” (watertable) & Datum “B” (breech face)

—

In practical use this is tantamount to your hand placement acting as Datum “A”, cheek acting as Datum “B”, & shoulder acting as Datum “C”.

Think about it, what is this doing and why is consistent mount along with firm placement so crucial?

Because you are handling the manufacturers Datum ‘A” (watertable), Datum “B” Breech face, and Datum “C” (chokes)

If the manufacturers intended design is not wielded properly what happens?

You miss

(Obviously this ignores eye coordination etc)

—

I will respectfully side with Parker on this one ~ all choke work should be done from the breech.

That said, I approach this from a manufacturers perspective so take it for what it’s worth.

[Paul Harm]

Scot, you don't have to " cast the choke area " - just get a inside mic and write down a reading every 1/4". JMHO, but I believe a lot of people think removing .005 of material on a side [ that's .010 total ] is rocket science. I used .005 as an example and that would be like changing a full choke to modified. I'm also a backyard machinist, but if someone has a basic knowledge of machining then you should be able to remove that .005 without screwing it up. Opinions are like a**holes, everyone has one, and that's mine. No offence to anyone - have a good day.

[Harry Collins]

My father opened a Parker and so did I. Both were horrible mistakes that give me bad dreams. Papa's was a VH 12 with 32" barrels and was his duck gun. When steel shot became the law he opened both barrels to improved cylinder and the chambers to 3"'s. Steel shot did not rifle the barrel and it continued to pull ducks out of the ozone layer. I had a GH that was improved cylinder (.012 constriction) and I had no idea what the left barrel was, but I had it opened to IC (.010). It was my sporting clays gun and I did well with it. I just wish both were still original.

[Eric Johanen]

Believe the photo of the smith is August Pachmayer in his shop late 50's or 60's. He had the reputation of "Master Gunmaker" and his work was highly regarded. My smith has done very nice work opening chokes for me on two guns sleeved full and full. Set to light modified and a bit over modified. Perfect for birds in the field and they are working really well on the clays course from close in to far out. Centered clays are crushed and they allow the gun mount with no rush for field shooting. I do not open chokes on original barrels and do not like to change from the constriction they came with. 43 and 45 points was just stupid tight and really needed something done.

[Scot Cardillo]

Thank you Eric..your post got me looking at the pic again.

At quick glance I mistakenly identified that machine as a cyl. grinder less the tailstock & modified for the specific task.

I was wrong - that is a honing machine..one built for deep hole work. As William pointed out, the barrels traverse left to right.

The stones can be adjusted as material is honed away..it appears he is making a stone adjustment to do just that in the photo.

[William Davis]

I just opened up a couple of Ponsness Warren Shot bushings on my lathe. How much to open was guess work & to increase drop 1/16 oz does not take much. I made a tool to hold 280 grit paper. Put the bushing in the 4 jaw indicated center and lapped. Few papers through the bushing took it out weighed a shot drop, and chucked it up again. Slow part is checking then re-chucking, half a dozen times but came out perfect.

Next one I made up a boring bar and cut the first step, it dropped right on desired weight so I omitted the lapping. Bushing works fine inside surface is not smooth. Not a choke job but the principal is the same.

Seems to me to do a choke right same method, lapping and testing is the way to go. Proper lead lap not my quick paper rig. I say lead because that's how rifle barrels are lapped. Might be a smooth bore large hole stone would work better. Very labor intensive all the set up test then set up again. Although a lap cuts fairly fast if it fits well and carries aggressive grit. Going slow and checking progress on the pattern board could give good results. That rig in the photo would be a good set up to open with a lap. Appears he can remove and re-set fairly fast.

More than one way to do a job all they all work. I am probably over thinking it.

William

[Paul Harm]

Brownells sells flex hones, 180 grit and 800 for barrel polishing. Thirty years ago I made a muzzle loading trap gun and did a jug choke with emery paper and split rod. It seemed to take forever. But that was with steel and a 6" section of barrel and .010 deep. I would never try that again. Glad I found out about Brownells.

[Frank Srebro]

I don’t know much about Parker factory choke profiles but several Parkers I owned and measured had tapered chokes right out to the muzzle, similar to A H Fox guns. Fox used a full taper choke profile during the Philadelphia era and that carried over to about the mid-point of Utica/Fox production. The Fox choking was done from the breech end and the tapered reamer was run in farther toward the muzzle to make increasingly more open chokes: X-Full --> Full --> Modified --> Imp Cyl. Even the “Fox Cylinder” choke had a few thou of tapered constriction depending on the gauge. The same thing could be done from the muzzle using a reverse-tapered "draw reamer" but it's far more complicated and would require a rigid lathe setup or similar.

Just for info, here’s a tapered reamer I made for 12-gauge to open chokes from the breech end and have it absolutely concentric with the bore. It was an expensive setup with the custom made reamer that matches the nominal Fox taper along with a set of bronze centering bushings at .003” increments, starting at .724” diameter for real early Fox guns, and ending at .748” diameter for use in the largest bore Super-Fox guns. The drive rod was made from TG&P steel shafting. Works like a champ and the newly cut choke(s) will essentially duplicate Fox factory work.

JFI, I made this up for my own use and am not "in the business". One of these days I’ll get the same setup made up for 20-gauge and maybe for 16. Generally I'm an advocate of leaving factory chokes as made but there are times to open them - and then I want the choke to be tapered and without a straight/parallel section at the muzzle as done with adjustable reamers, just my preference. Personally I don't test shoot the gun for pattern % while doing this work; I did that first off quite a bit but determined to my own satisfaction there's a very good correlation factor between bore and exit diameter at the muzzle, and pattern %.


The back end of the reamer has a 1/2" long straight section and then the taper begins. Reamer was just used yesterday and isn't cleaned as yet, some small cuttings in the flutes.
http://i1044.photobucket.com/albums/b450/silvers897/02/IMG_7254_zpspsshd3n9.jpg (http://s1044.photobucket.com/user/silvers897/media/02/IMG_7254_zpspsshd3n9.jpg.html)

Plenty of length to use in 32" or even longer barrels and still clear the barrel extension.
http://i1044.photobucket.com/albums/b450/silvers897/02/IMG_7255_zpsrhld1cqi.jpg (http://s1044.photobucket.com/user/silvers897/media/02/IMG_7255_zpsrhld1cqi.jpg.html)

The drive end is square for a large tap handle
http://i1044.photobucket.com/albums/b450/silvers897/02/IMG_7256_zpsctv9tmik.jpg (http://s1044.photobucket.com/user/silvers897/media/02/IMG_7256_zpsctv9tmik.jpg.html)

[Paul Harm]

Frank, nice tooling you made up.

[William Davis]

2nd Paul's comment. Nice set up. I doubt if any of us changed our opinion's but all have learned something about choke work for sure

William

[Bill Murphy]

Frank, that's a beautiful setup. However, I question how so many people who are making a living messing with chokes can come up with such destructive work. Just like you, I think my machine work is better than any I can buy, or I won't do it. Good work.