choke question
 

I have a PH model made in 1891 with twist barrels. It is 12 gauge, but mics at Right barrel = .739 and Left barrel = .730. My mic only drops in the barrel about 3/4 of an inch. Am I reading this wrong? The guy who sold it to me said it was IC and M.

Am I thinking in the wrong direction? Shouldn't the choke be smaller than .729 for 12 gauge?

John

Your gun, like most Parkers of the period, likely has oversized bores. I have measured some 12g barrels to be as high as .750". In order to determine the chokes in your barrels, or any barrel, you NEED an actual bore gauge so that you can measure the bore diameter and also the amount of constriction at the muzzle. The constriction is the amount of choke, regardless of what the bore measures.

A drop in choke gauge or calipers on just the muzzle would only be accurate if the bore was actually .729".

Ditto to what Brian said. Choke is determined by the difference between the measurement at the muzzle, and the back bore. Measures at least several inches back. Start with a bore guage, end with a pattern board. The gun will tell you what it is.

This is why I've gone to patterning my shotguns the last several years. As a younger man, I was content to announce a gun's choke as whatever was roll marked on the barrel. Then, I began trying the measurement game and found bore and choke diameters varying pretty wildly from industry standard, as indicated by Brian and Todd in their posts. Eventually, patterning came to be my preferred way of actually knowing what I had. It was eye-opening to learn how easily I could manipulate pattern density by changing shell configurations, but the results of these changes are immediately obvious on the pattern board.

The little 16 ga. Parker bird gun I'm so fond of has odd bore and choke dimensions as I recall, but I can't remember the exact numbers sitting here at 3:30am. Regardless, it was averaging 58% (modified) patterns from the left barrel and 52% (*quarter choke) from the right at 40 yards with the load I was shooting. I recently switched to a different brand, dram equivalent, and wad type, so need to start the process all over and see how things have changed.


*Quarter choke, as I understand it and according to the chart I've adopted (from Jack O'Conner, I think), is of British origin and represents a choke having just a bit more constriction than our American improved cylinder. The chart goes something like this, according to notes I have scribbled here, and is calculated at forty yards:

Full Choke: 70% or above
Improved Modified: 65%
Modified: 55-60%
Skeet No. 2: 55-60%
Quarter Choke: 50%
Improved Cylinder: 45%
Skeet No. 1: 35-40%
Cylinder: 35-40%

I finally broke down and bought a proper bore gauge. It gives a very good indication of how the barrel is choked, however how they pattern proves how they throw shot. Not all my guns that measure the same throw shot the same on paper. Look at point of impact too even more differences. And like John said the load is another factor.

May be if I ran more patterns they would match up or perhaps not. There is a limit to how much testing I am going to do but measuring and patterning is important if you want to know what the gun is going to deliver on targets or game. I know I have changed some of my loading as a result of patterning

William

Thanks to all three of you guys. You have helped educate me on this issue. I knew if I put it on the forum I would get sound input. I really appreciate it.

John

I am putting two Parkers in the car now for a round of Clays today. One is 20 G short and open other is 12 G long and tight. Will shoot the first half of the course with one 2nd half with the other. My shooting buddy the same pair of Parkers 20 & 12. Knowing how they throw will make a difference in how I take the shots. Short gun will probably go fast and try to break close to the trap. Long gun let the target develop and look for a break further away ( or the reverse if incoming) Other thing is I have gone to two shot sizes. 7 1/2 for the tight choked gun # 9 for the open gun.

At my age and eyesight need all the help I can get to hit targets. In the end choke is probably not all that important miss is a miss no matter how the gun is choked. Confidence is very important and knowing the gun makes a confident shot.

William

Thanks William. Have a great day shooting.

John

John

I should have added 90 % of what I know about Parker guns came from this forum. It's a wonderful resource

William

Just to add my two cents worth to this discussion.

All of the above posters are spot-on with their explanation of choking. Parker themselves relied heavily on the patterning board for the purposes of determining the choking of a particular set of barrels.

I have several PGCA letters on the various Parkers I have owned. In a majority of these letters Parker in their records recorded choking as percentage of a certain size of pellet patterning in a specific size of circle at a specified yardage. As an example "left barrel patterns 180 pellets of #7 shot in a 30" circle at 40yards distance"

In my small sampling of letters. I have found this to be the normal means the factory used to determine choking. I do have a few letters where the chokes are stated as Full & Full, IC-Mod etc. My conclusion based on the letters I have seen is that Parker spent a lot of time at the patterning board to get their chokes just right for any particular gun.

Bottom line is the only way to really determine how your gun is choked is to spend time at the patterning board.

Bore micrometer, the one that most of us use, Skeets brand, Brownell's catalog, about $95.

That's the one

William

I've got one at the shop that looks like a set of calipers but with about six inch depth capabilities . Don't really care for it however but it's better then nothing . I do have a good friend that has a nicer one that's good for everything from 10 gauge to 410 and that thing from Brownells was like $700 !

I'll second the Skeets gauge. I believe the Parker Story talks about the change in bore diameter happened in the early 1890s. Austin Hogan did research on this also. The 1879 lifter I had had bores of .750 with about 30/1000s choke in each barrel. I miss Austin. Every time he spoke I learned something new about Parkers.

You can sure say that again!





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Yup, Paul nailed it. Fox did the same thing. They patterned the guns for specific chokes. I see it would be the technologically correct way to get the actual choke/pattern combo instead of the modern industry standardization, but I wonder if there was more to it than that? Issue with components and reliability? Difference in individual barrel smiths and the way they made their product? Difference in machining? Anyone know?

I don't know for sure Mike, but probably a combination of all of the above. Of all the things that fascinate me the most about Parkers and Foxes are their attention to their choking. A true shame to screw with them.
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I need to make an addendum to my post. Fox did pattern some guns when it was requested to be certain percentages or with a specific load, they didn't pattern every gun. That would be expensive!! :shock:

I've seen a lot of Parker hang tags, including many Trojans, and I have never seen one that hasn't been patterned.




.

Great point Dean (as usual:)) but today we would be unable to duplicate Parker's load. So getting back to John's OP, John, pattern your gun for point of impact, then try different loads as see which ones your gun likes. Don't worry about your chokes. You can get them tighter or more open by changing loads. Shoot a few hundred clays with it and you'll get a feel for her performance.

Attached is a graph that Austin Hogan made. As you can see, around S/N 65k and before 1891, the bores were oversized. After 1891 or so, the bore diameter was brought down to nominal size of .730 or so.

The majority of entries in the order books do not show what the chokes should be. When chokes are listed, an example would be RH cyl, LH full, or RH modified/LH full. Occasionally in the order book you could sometimes see the customer wanted a certain number of pellets for each barrel, the size of the shot, the distance, and the diameter of the circle. In some cases, they also indicated what powder to use, what pellet size, and the weight of the pellets.

If it's not listed in the order book but we have a stock book entry for this gun, we can get an idea of the choke by looking at how many pellets hit within the circle. Problem is is that when they copied the stock books the scanner wasn't long enough to include all the info found in the stock book. Depending on how the book was placed in the copier the patterning info is not there or just the pellet count can be seen or you may see the pellet count and the size of the shot, or in the best case, you see the number of pellets, the size of the pellet, the distance, and the diameter of the circle. This is why we want to get access again to the original records. If the chokes were different in both barrels, each barrel would have it's pellet count. If only one entry for the number of pellets, both barrels were the same choke. Also remember that a #8 size shot varied depending on who manufactured the shot. I think Parker mostly used Tatham shot. See the attachment.

The original stock books had more information after the patterning column and I think it showed what powder was used and some additional information at the end of the page. This is why we want to get access again to the original records.

Thanks guys. I am learning a bunch from you all.

John