doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com What are the true choke sizes?

Dr. Andrew Jones reported in his book, based on 2500 carefully analyzed patterns, that patterns are so variable as to make choke only a basic pointer as to the performance of any shot from a given gun and load. Gun performance based on the firing of one shot is highly suspect. The practice of "fiddling" with a choke and shooting patterns until the desired result was achieved seems to have had more to do with luck/statistical probability than with choke adjusting skill. I've never heard of anyone firing nine more shots and reporting the gun performance as a set of statistics based on ten shots.

sxsman1, I've not read the mentioned author, but I have say, IMO, he has surely reported inaccurate information.

As above, choke constriction is measured in thousandths of an inch/decimals of a mm. The names applied are largely arbitrary as there is yet to be a real, generally accepted standard.

Walt,

Thanks for posting those hang tags. That recommendation for buckshot sounds like just a way of buffering the buckshot with little shot, instead of the buffering compounds used today.

Very interesting.

SRH

The hang tags are very interesting. I don't think that the gun manufacturers actually honed the chokes out to have the guns reach a certain pellet count. I think the guns were choked to a certain set standard,then shot, and the pellet count reported.
If the gun didn't pattern to a set standard , then they might be tweaked until they did.
I think the practice of using terms such as full choke, I/C, and modified are unreliable at best. It is much more informative to say your gun is choked .035 then to say it's choked full. Wich could be anything from .020 to .040.

Pete
Pete

It's always interesting to read on this site some people that buy a gun that is listed as having mod/full choke choke ( or whatever) and even before they have it in their hands they want to know who they can send it to have the chokes opened.

As stated before L.C. Smith stated what they used to pattern the gun at a specified distance and the pellet count. They also stated that if you wanted something different, list the pattern you want and the shell you are using and they will bore the gun and pattern it to your specifications.

I found where the author of the book "The Art of Wing Shooting" Leffingwell, got the idea that modified chokes were five thousandths constricted. In the chapter on chokes he refered frequently to Greener. I looked in the book "The Gun and it's Developement" In the chapter on choke boring, he writes..."To an English gunmaker the terms (choke boring) mean simply "barrels whereof the diameter of the bore at the muzzle is less than the bore at some point behind the muzzle, other than the chamber," while any gun-barrel constricted at the muzzle to the extent of 5,000ths of an inch may be termed a modified choke." He goes further and writes..."A full choke is constricted to the extent of 30 to 40,000ths of an inch." This makes more sense. It seems Leffingwell was quoting Greener and maybe he wasn't very well informed, but then choke boring was new and maybe a lot of writers wern't fully knowledgable.
Pete

What Bro. David said

The average bore and choke dimensions (inches) were

Gauge Bore Improved Cylinder Modified Full
12 0.732 0.725 0.710 0.695
16 0.662 0.657 0.639 0.629
20 0.615 0.610 0.595 0.585

Starting in 1907, Hunter Arms catalogs included the following statement:
�All Smith Guns are bored full choke unless otherwise ordered. We bore all our guns according to our Multiplied Choke Bore System, which has made the Smith Gun famous the world over for long-distance, chose-shooting and hard-hitting qualities. We can bore a gun as follows using the twelve-gauge gun as a standard distance, forty yards; circle, thirty-inch; shot, Tatham�s chilled No. 7 1/2, one and one-quarter ounces; American Association Measure, 345 pellets to the ounce or 431 to the load.�

Full choke��������70 per cent or 301 for pattern.
One-half choke������60 per cent or 258 for pattern.
One-quarter choke�����50 per cent or 215 for pattern.
Improved cylinder�����45 per cent or 193 for pattern.
True cylinder�������35 per cent or 150 for pattern.

Drew--You wouldn't happen to have the guage bore specs for 10 gauage too would you?

I have two Parkers in the 1905-7 range. Both were bored .040 within a thousandths of an inch on their left barrels.

I'm suspicious that makers tested and developed chokes for pattern density, then replicated the dimensions for production of guns. It would be interesting to have a survey, comparing a maker's diameter variation for a given choke. The problem with a survey of that sort, of course, is that these guns are the better part of a century old and could very well have been polished out, honed, reamed, etc., so the data would be of little value.

From my little knothole, if someone told me they have a Parker, LC, Fox, etc that had a full choke marked gun that had a measurement that was something outside of what I would expect, I'd be looking for indications that it had been modified.

Regardless of all the banter about pattern density, choke in thousandths of an inch is the only information useful to me when assessing purchasing a used gun. This is because: 1) I wouldn't know what load was used if pattern density was given instead of dimensional choke measurment, 2) it's unlikely I would use only that load or use it at all (we all have our pet loads), 3) the components for that load are probably no longer available if the load was from yesteryear. 4)I'm not so concerned about pellet count as to select say one gun over another, when going into the field to hunt, but rather more along the lines of this gun has tight chokes, this gun has medium chokes, this gun has open chokes, this gun makes me feel good to hunt with, etc., 5) I have a general expectation of performance based on choke dimension that has proven very reliable to me (nobody selling a gun could convince me that their 12g gun with a .025 choke would perform as I would expect a full choke gun to perform on a variety of loads without demonstrating it.

Frankly, I think the industry for production guns has long ago moved to a dimensionally based choke approach. Besides, pattern count is just one way of quantifying tight, tighter, looser.

J.R.B. - sorry, wasn't paying attention. p. 230 of Brophy's shows the "1906 style" spec at .775. As JDW said on another thread, the Syracuse 10s were probably the same.

I agree that choke size should be in thousandths of an inch. But more importantly when buying a used gun, is to know the bore size. Without this, choke size doesn't mean much.