Bore Gauge questions
 

Hi folks.. Just received my Gary Bulley 10-12-16 bore gauge. Damn what a great guy and product and price. Now for my stupidity to show, since this is new. I have 15-20 pieces to measure but want to be clear about something.

I have the 18" dial model and insert to get the bore reading, then pull out looking at the amount of constriction.

First question is, if "nominal" diameter is .662 (16g) and I get .665 or something, is that usually from boring out, or are Parkers pretty much consistent in their stated diameters? I have other guns to measure too.

Second, when measuring the choke, do I take the gauge ALL THE WAY until the little bearings are ready to come out? The reason I ask is that I'm surprised how much constriction one of my guns has. Going from .10 to .22! in like the last half to three quarters inch it seems. Barrels are factory length. I expected a much more gradual taper.

Finally, as I got this late last night and not much time, can I expect to go from the breech end and find forcing cones in a Parker?

Any advice, thoughts...etc appreciated!

The more open the factory bored thr chokes, the shorter the length of constriction.





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Congrats on the new toy! I have a Stan Baker all-gauge set and love it. As far as "nominal" goes, it is just that. I don't think a couple thousandths either side will make any difference and would be in tolerance levels.

In my experience measuring the choke area, I do try to get right to the edge of the muzzle, but make note of where the most constriction exists. I have seen some chokes (not Parker) that had a "huge" difference in the last <1" and some that have a long parallel segment, then a gradual taper and a few that actually close then open up at the end. So, I guess you can find any type choking but as far as Parker chokes, I can't say one way or the other what a 'standard' Parker choke looks like.

It is fun to see how consistent those "good barrels" are.

I appreciate the comments! It's a cool toy.

Austin Hogan plotted the bore and choke tapers on many Parkers and I have several of his graphs. I will post them here on the forum whan I can.
He told us that the Parker Bros. chokes began with an ogee from the bore into the taper and ended with an ogee from the taper to the parallel terminal 1/8” - 1/4” at the muzzle.





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Would love to see that Dean.

Great gauge but the price for the custom case was hard to swallow.

https://i.imgur.com/xfgrvlM.jpg
https://i.imgur.com/BNLzG6i.jpghttps://i.imgur.com/8wuDzmS.jpg?2

Yeah I got the gauge only. The custom cases are gorgeous, they're un used stock blanks. I'll probably just go to Harbor Freight and get a case and some foam.

Bore diameters vary with maker and era. I have a 1929 LC Smith 16 that measures .646 bores. .650 +- was standard for their pre 1930 era 16 ga guns according to those who know. .662 afterward. Similar thing applies to some Parkers. Early 12 bores typically mic'd .750+- according to research done by AH while later 12's came down to .729. Within those parameters, there is some small variation I have observed of 1-3 thousandths. Outside of that, I would suspect honing, reaming, or backboring depending on the amount. I would not worry about your .665 barrels. Whether factory or honed, its not enough to make a difference IMHO.

Thanks Mike, appreciate it.

Andy, I don't know anything about the bore mike you bought and perhaps it's atypically good, but generally those sold for a wide range of shotgun bores but with a single measuring head and one calibration ring will "drift" at the high and low end of its measurement limits. Thus readings will be most accurate within a narrow range +/- of the calibration ring diameter. Otherwise it could be several thou off true size. I well remember a popular bore mike I had at one time that was .015" off true size when calibrated at .700" diameter and measuring a 10 bore. After that I bought a Stan Baker bore mike set with three measuring rods and three calibration rings.

PS: I here use the machinist word "mike" rather than "mic" as seems to have been adopted into shotgun terminology nowadays. :)

Parker bore diameters for 12 ga. guns up until about S/N 60,000 are over-bored. I'll let Dean display the chart from Austin. My 1882 12ga. hammer gun measures .756. I have yet to measure a Parker 12 ga. that reads the nominal for a 12 ga. at .729. They are all .732 or a few thousands higher. Don't know about other gauges. I have the Stan Baker micrometer set.

All new to me and thanks for feed back Frank and Chuck. His gauges seem to be very well received and reviewed and he's been helpful and this is the 10-12-16 gauge set. Chuck I do have a 12 g "live pigeon gun" that measure .730 on the nose. I agree the few thousandths don't matter I'm just trying to learn. And figure bore constriction.

Now, to complicate matters, I have a 16g Trojan that measures .660 R and .672 L or so. What the heck. Both measure F/F with a Galazan drop in gauge but constriction is more like LM/XF. So much to learn.... The gun is high condition and matches the "book"

These pictures are from one of Austin Hogan’s several notebooks. They are all hand plotted by Austin and accuracy was his middle name. I wish I had been in on the conversations with him and Charlie Price and Bill Hoover and Bill Furnish, all very serious students of Parker guns.

For the porpose of this conversation, charts are simply to illustrate the fact that none of the changes in chamber to bore, as well as the chokes, didn’t begin or end with an abrupt angle but folllowed an ogee.


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I have no doubt as to the accuracy of Austin's measurements and drawings for those specific guns but I often wonder when I see a "swell" (short enlargement) of the bore as it starts into the choke leade. Austin shows typical ogees but not swell profiles. Anyone who's measured enough shotgun bores with an accurate bore mike has seen that swell on various vintage makers and to include some earlier/modern fixed choke guns, for example Winchester 101's. Typically on heavier choked barrels and supposedly to act as kind of a short run overbore for bare shot.

Frank, I wonder if the swells you describe are a result of jug-choking which is done from the muzzle end of the barrels in order to increase the bore dia. immediately before the constriction of choke taper had originally begun…?




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Dean, I don't know if the swell was done from the breech or muzzle ends but it's long been described as a way to "normalize" the bare shot charge before starting into the choke. It's not as pronounced as jug choking. The earliest references to the swell I've seen were by Askins and Sweeley in the early 1920's as they experimented with borings and chokes for max long range pattern efficiencies, that was prior to the advent of the Super-Fox which was largely based on their work. What I wonder about now is what effect, if any, the swell has on performance with plastic shotcups. One of these days I'll do some comparative long range patterning with bare shot and shotcups to check for myself. Actually I had planned to do that in part for a DGJ article and that's why it slipped to the back burner when the editors pulled the plug. I've seen these swells on a few Foxes, Parkers, Winchester M12's, M21's and 101's.

Frank, I'd be willing to bet that those "swells" will have little if no effect when using plastic wads. As you well know that these plastic wads used in vintage guns designed to pattern loads with no shot protector have become a game changer in better patterns. JMO of course.

Andy, I've got a few instruments for measuring bore/choke dimensions and I've found very little concern over a few thousandths difference. I am concerned over bore diameters which are wildly over bored. Chokes, not so much. I'm always surprised on how they perform (the choke) even though they don't jive with the charts.

Thank you Daryl. Yeah, I'm in geek mode right now I guess. I have a 16g on 0 frame which the muzzle choke device says is F/F and it's been a great grouse gun and I think it shoots more like a LM/LM. I'm going to measure that one for sure this weekend. Perhaps I will at least look like I know what the hell I'm doing.

I've said this before and I'll say it again Andy...Just shoot the damn thing and forget about the chokes. Looks like you're doing that with that 16/ O frame:whistle:

Daryl I think you're sorely mistaken. It has nothing to do with shooting it, I just want to have an inventory of my stuff and make better buying decisions. I don't pay much attention to chokes. I have ordered a Perazzi and I'm considered a heretic because I did NOT get screw in chokes. I hate choke tubes and shoot what I got. The only thing I don't like is very open chokes all the time. Not enough dust is created that way.

Like the bank robber said to Dirty Harry while Harry was standing over him
pondering whether he had fired six shots or only five,

"I gots to know...".

Good one Bobby! : )

Frank - AH Fox No. 31088 chamber, bore, and choke measurements from Austin's files.

Presuming most folks still reading this thread know 31088 Super Fox was Buckingham's "Bo-Whoop".

https://parkerguns.org/forums/showthread.php?t=32142





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Didn't mean it that way Andy. Just saying that you do so well with your tightly choked 16 and yes, for reference purposes and for better buying conditions you are on the right track.

In the last year I have acquired 3 Perazzis, a 12, 20 and 28. Only the 12 has screw ins and they came with the gun. They are Teague and they are wonderful. Written in bold letters inside the tube case is "do not underchoke". I leave the M and IM in full time. The MX28 has fixed M/IM and the MX20 has M/M. Yea, I like em tight.

I love Perazzi's : ) I'm waiting on my only one (should say FIRST one) to be delivered.

BINGO!! If you put the muzzles at the right place you’ll hit what you’re shooting at no matter what the choke is.

Andy, good all around chokes would be on both sides of Mod. LM, M and IM. The IM is close enough to F for those that like “diesel smoke” while LM is tight enough to reach out and break a longer clay. I had full length sub-gauge tubes made that stay in each barrel set. They were made to fit those specific barrels. They are all fixed chokes. I did LM/IM in each. Fun to shoot. Crush targets when I do my part.

Thanks Mike. The only gun I really struggle with is my go to grouse gun choked C/IC if I'm shooting clays. All my Parkers are German choked...Gutten-tight

The Perazzi will be LM/IM and I can shoot spreaders if I feel the need to. I think my choke tubes in my Beretta 694 have been in there for three years, I should see if they are welded in : ) I'd rather floss my teeth than clean choke tubes.

Andy, trust me when I tell you the Perazzi will blow you away if you are serious about breaking targets. What model did you order?

Daryl, I ordered the MX8 31.5" fixed LM/IM with the 11x11 broadway trap type rib. Dropout leaf springs. From Pacific Sporting Arms. It will be one year next month. I'm dying waiting. I love how they shoot. I may not shoot better but life is short, right? :)

Good choice of chokes. Spreaders are the nuts for close targets, especially rabbits inside 20 yards.

There was some crazy dude down in Meshoppen, PA, who once did a rabbit inside 20 yards on station 9 that only momentarily appeared out of a gully for about 2 nanoseconds. Sadistic SOB if I remember correctly.

What a bastage!!! Can't believe anyone would torment such pleasant shooters with a target like that! I will give him a stern talking to and let him know 2 nanoseconds is way too much time. :cool:

You will shoot better. I have the MX2000 with the tram line rib. Love it. But the MX28, now that's a whole different puppy.

Yeah that's a bit above my pay grade Daryl but I've shot one. W O W.

Over the years when I was doing serious NSCA competitions I owned three UK spec Perazzi MX 2000's in 12 gauge and one in 20 gauge. All but one of them were 32" and one 12g was a 34". All were ordered with fixed number 5 and 7 chokes. I agree P-guns are the nuts for sporting clays though expensive and long delivery.

Several months ago I came across a Browning CXS White Combo in 20 and 28 bores. Both barrel sets are 32" and both non ported. Factory stocked to shoot about flat and mine prints just a tad high. Love it! This 2-barrel combo was a Browning 2022 Shot Show Special, now discontinued, but they can still be found brand new on-line at less than $4k. JFI.

I actually sold two smallbore (20) Parkers to buy the MX28 and walked away with cash in my pocket. Wish I had done it years ago.

Andy, any update on your Perazzi?

I've shot a Parazzi MX-8 for about 12-14 years. I was shooting it about the time I punched into M class in the NSCA, at the 2010 US Open. Mine is an old gun, imported by Winchester and so stamped, and was originally a trap gun with 31.5" barrels, F/F chokes, non-selective trigger and a high stock. I swapped stocks to get it to shoot 60/40 and had the chokes opened to M/M, figuring that since I couldn't select barrels (chokes) I should have the same thing in both.

I have never regretted that decision. It remains a highly competitive gun for me and, even at it's weight (9 lbs.) it handles like a dream. I love the freedom that comes with not messing with changing choke tubes for certain presentations, and focus wholly on the targets at hand while my buds are swapping chokes to gain a perceived advantage for themselves.

Spreaders are the ticket for very close stuff and unpredictable presentations like rabbits. My favorite spreader load is the Fiocchi Interceptor, in no. 8s. I've loaded spreaders of every conceivable persuasion but have settled on these factory spreaders after patterning them years ago, then seeing the results. They are just awesome.

Congratulations on the new Perazzi, Andy. They are just wonderful target crushing machines.

https://www.hinterlandoutfitters.com...es-p-6001.html