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#141473 - 03/24/09 08:26 PM Choke guide chart? Looking for info on choke sizes
Victor23 Offline
Boxlock

Registered: 03/16/09
Posts: 19
Loc: FL
I have several guns that have more than one number stamped on the same barrel. Did someone change the choke?
Anyway, Does anyone have a link where I can decifer the chokes?

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#141476 - 03/24/09 08:34 PM Re: Choke guide chart? Looking for info on choke sizes [Re: Victor23]
Subgauge Offline
Sidelock
*

Registered: 09/06/03
Posts: 257
Loc: Western Pennsylvania
Make? Model? Date of Mfg.?

There is no "standard" all were different.
_________________________
Mark

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#141537 - 03/25/09 11:55 AM Re: Choke guide chart? Looking for info on choke sizes [Re: Subgauge]
ChiefShotguns Offline
Sidelock
**

Registered: 01/02/02
Posts: 2226
Loc: Georgia
Chokes actually are the difference between actual bore diameter and choke diameter. Named "chokes" (i.e. IC, Mod, full, etc) will vary from one barrel to another from the same maker. They also could have been altered at some time. You need to actually measure what each individual barrel is and subtract the two readings to determine your real choke.

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#141547 - 03/25/09 02:23 PM Re: Choke guide chart? Looking for info on choke sizes [Re: ChiefShotguns]
Tyler Offline
Sidelock
**

Registered: 01/02/02
Posts: 658
Loc: West Alabama
This is from my files, I saved it from a earlier post. Reprinted without permission.
Tyler


Here is a copy of something I put together in response to a similar question on another BB.
The traditional way of designating chokes (before the advent of interchangeable choke tubes) was by the patterns they produced. Don Zutz says (in a chapter of Lyman's 4th Ed.) that all pattern percentages are measured in a 30" circle at 40 yards, except for the .410 bore, which is measured with a 20" circle at 20 yards. He cites the following percentages as "industry standards" without specifically naming SAAMI.

Cyl 40%, Skt 45%, IC (British 1/4 choke) 50%, Skt 2 (often called light Mod, Brit 3/8) 55%, Mod (Brit 1/2) 60%, IMod (Brit 3/4) 65%, Full (British "choke") 70%, Ex F 75%.

Every combination of gun, choke tube, and shell may produce a different percentage, so many manufacturers of choke tubes have adopted constriction designations instead of percentage designations. I really don't know if the manufactureres are consistent (I suspect they are not) but the famous shotgun gunsmith Ralph Walker listed the following constrictions in The Gun Digest Book of Shotgun Gunsmithing, 1983.

12 GAUGE: Skt .005, IC .009, Skt2 .012, Mod .019, IMod .025, F .035. These are close, but not quite the same as Briley's specs, as printed on the back of a business card (about 1998 vintage) from Stephen Power, Sales Manager, which are as follows: Sk .005, IC .010, LM .015, Mod .020, IMod .025, LFull .030, F .035, XF .040. It looks like Briley has simply rounded off the numbers for the sake of convenience.

Continuing now with Walker's data:

16 GAUGE Sk .004, IC .007, Sk2 .010, Mod .015, IMod .020, F .028

20 GAUGE Sk .004, IC .007, Sk2 .009, Mod .014, IMod .019, F .025

28 GAUGE Sk .003, IC .005, Sk2 .007, Mod .012, IMod .016, F .022

.410 Bore IC .004, Mod .008, F .017

Now I am begining to wonder why I went to the trouble of looking up all this data and typing it. I guess it is because I am an engineer by birth as well as by education, and engineers just love data. I have been suffering from data withdrawal since I retired. I hope someone finds it usefull. You might want to copy this response and save it as an MSWord or WordPerfect document, for future reference. I will, because I don't want to have to get my data fix this way again!

Jim Cassada (No, I am not Jim Casada, the writer/editor!)

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#141549 - 03/25/09 03:01 PM Re: Choke guide chart? Looking for info on choke sizes [Re: Tyler]
bamboozler Offline
Sidelock
**

Registered: 01/01/02
Posts: 510
Here's a link to Briley's Choke Chart:

http://www.briley.com/2009/chokeconstrictions.html

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#141557 - 03/25/09 04:09 PM Re: Choke guide chart? Looking for info on choke sizes [Re: bamboozler]
Remington40x Online   content
Sidelock
*

Registered: 12/11/06
Posts: 748
Loc: Warrington, PA
What would the equivalent choke constrictions be for a 10 gauge?

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#141559 - 03/25/09 04:30 PM Re: Choke guide chart? Looking for info on choke sizes [Re: Remington40x]
bamboozler Offline
Sidelock
**

Registered: 01/01/02
Posts: 510
Here's Colonial Arms Choke Chart for 10,12,16,20,28-ga's. and .410 caliber as well as true bore diameters for each:
http://www.colonialarms.com/chokespecs.html

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#141567 - 03/25/09 05:13 PM Re: Choke guide chart? Looking for info on choke sizes [Re: bamboozler]
JDW Offline
Sidelock
**

Registered: 02/04/06
Posts: 2609
Loc: Eastern Pa
Originally Posted By: bamboozler
Here's Colonial Arms Choke Chart for 10,12,16,20,28-ga's. and .410 caliber as well as true bore diameters for each:
http://www.colonialarms.com/chokespecs.html


That is a good reference to go by, but some manufacturers of 16 ga, especially L.C. Smith, the bore of pre-1930's guns is .650, changed to .662 after that along with chamber length.

The other thing is, without knowing bore size, choke diameter means nothing. Actually the only way to know what your choke is, is to shoot 5 rounds at a pattern board, choke size means nothing until then they are just numbers.


Edited by JDW (03/25/09 05:18 PM)
_________________________
David


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#141717 - 03/26/09 08:16 PM Re: Choke guide chart? Looking for info on choke sizes [Re: JDW]
2-piper Offline
Sidelock
***

Registered: 12/31/01
Posts: 9978
Loc: Lynchburg TN
Old bbls designed for card wadding usually had the bore area (not dia) reduced to a range of 89-90%, thus √(90%.729²) =.692 or .037" constriction. Plug in any other dia you desire. Later guns for more efficient wadding open this to a reduction more on the order of 92%. This gives a dia of .699" or .030" constriction from the standard .729" for 12ga.
_________________________
Miller

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#141871 - 03/27/09 06:49 PM Re: Choke guide chart? Looking for info on choke sizes [Re: bamboozler]
Patriot USA Offline
Sidelock
***

Registered: 01/31/09
Posts: 466
Loc: peoples socialist republic
Originally Posted By: bamboozler
Here's a link to Briley's Choke Chart:

http://www.briley.com/2009/chokeconstrictions.html



Is there any reason why Briley has the same dimensions for 20 and 28? I've pointed this out before but none had an answer.

I have always preferred Colonial's.
_________________________
Don't sacrifice the future on the altar of today

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