Thompson Center Encore Classifieds
Find your Encore Barrels here!

Home » Thompson Center Contender Classifieds » Contender Reference Only » Contender External and Internal Chokes (Use on Octagonal Barrels)
Contender External and Internal Chokes [message #32000] Sun, 29 June 2014 20:20 Go to next message
jamesgammel is currently offline  jamesgammel
Messages: 1711
Registered: August 2012
Location: Lovell, Wyoming
Top Contributor
There was recent discussion on using an Internal style choke backwards on a Octagon external style barrel. Fact is someone recently sold one set up that way on another, popular auction, sight.
TC made and sold 4 octagonal barrels with external chokes. 45-410, 45 Colt w/choke, 44Mag Hot-shot, and 357 Mag. They also made and sold 3 Internal choke barrels which were Bull's (or close), and vent ribs. All had some arrangement of "porting", and the chokes could be removed for shooting normal single-projectile ammunition. The 45 Colt,44 mag, and 357 mag used normal brass cases, and had plastic shot cups which were crimped in and held typical "bird" or "rat"(smaller) shot. Like most shotshells they were also used for such small game as squirrels, rabbits, and the like. The 45-410, was chambered to shoot normal 3" 410 ammo.
What did one of these barrels look like? Here's a picture of a 44 Mag Hot-shot barrel with it's external choke mounted:


There were two "flats" machined near where the barrel and choke join on the choke. A "spanner" type tool was provided for snugging it down for "shot" use, and also to loosen it for removal to shoot normal ammo. Note how it tapers down forward of those flats. The tube from where it touches the barrel to it's forward end is ~ 1 13/16" long. The ID at it's entrance is ~.468", and at it's exit, the grooves are .440 ID, the Lands .377". They are straight, not spiraled like rifling.

Here's a Picture of the two chokes,and the "tools" used to mount the chokes":


Going from Left to right: The first shown is a "key" provided for the internal style 44/45 choke. Second is a 44/45 internal choke. The third is a later devised, and sold Multi-tool It has a splined section similar to the 44/45 "key" for the same duty. The next long object is a 44/45 external choke "spanner" tool that was provided when the external 44/45 chokes were sold. The object to the far right, is a 44/45 External choke. The tools and the chokes have 6 grooves and six lands of approximately equal width. The tool is slightly smaller in OD so it fits quite easily.

Will a reversed internal choke screw into an external choke barrel? Yep, sure will. The threads are Identical and aren't tapered.
Here's a picture of a 44mag Hot-shot barrel with a 44/45 internal choke screwed in:


Note That the body has no taper from one end to the other like the external choke, and there's no "flats" for a spanner wrench to snug it. Gee, just use the "key" to snug? NOPE, won't engage the lands and grooves, there aren't any at all at the end, and don't start for about 1/4 inch. A 10" barrel with the external choke mounted measures 10 inches. With the internal choke mounted as shown, it's ~9 1/2 inches. Well, heck, losing 1/2 inch of barrel's no big deal, just wrap a rag around the choke and snug it with a pair of channel-locs, problem solved. Now all set to shoot it right? Nope, not if you value life and limb at all. Why not then? Well, the taper inside the choke is backwards, it's tight toward the hammer, and get's larger toward the exit end at the muzzle. Now what is likely to happen then? 1. IF the sleeve with the ports which is SOLDERED on for about 1/8 inch (it's fairly tight across the peaks of the hex, and the solder fills the voids underneath at the flats; not a whole heck of a lot holding that ported sleeve on. Decent chance it MIGHT just let loose and you've got a single projectile along with that shot column of sleeve, front sight, and choke tube. 2. If it holds, when that shot column hits the choke, the momentum may RIP the gun out of your hand and end up 10-30 yards on the ground in front of you. But Also, You'll likely have to learn to shoot with your other hand because it will also likely rip your trigger finger off and you'll be standing there in pain, and bleeding profusely. 3. It could also just rip the thread off the choke or out of the sleeve and the single projectile is now the shot column and the choke going downrange. 4. With the thinness of the choke and the sleeve, it could also just split the whole ball of wax and send shrapnel everywhere, maybe take out an eye, or cut a huge gash for lots of blood to spill out all over the ground. I think you should have the idea by now, it's not a good idea.

Now here's another thing to consider. The 357 choke is externally the same as the 44/45 external choke, uses the same spanner. Will one screw in? YEP. So if you have a 357 AND a 44 or 45 with external choke, better make sure you use the right one. The 44/45 on a 357 isn't actually dangerous, it just won't work worth a darn. BUT the 357 in a 44 or 45 barrel is a nightmare waiting to happen. The 357 choke has 5 (not 6) lands and grooves and the "walls" of the chokes are much thicker.

Moral of the story: 1. You CAN use an external choke on an internal choke barrel. 2. You better not use an internal choke backwards on an external choke (octagon) barrel. 3. Make sure if you have both 357's and 44 or 45, to use the right choke, Bigger in a small bore is a waste of time and effort, but smaller in a bigger bore is outright dangerous. If your barrel is missing it's choke, either don't use one at all, or get the proper one. If you have external and internal 44/45's and need the tools, just get either the 44/45 key or multi-tool. The spanner mars the blue when used.

[Updated on: Fri, 04 July 2014 22:17]

Report message to a moderator

Re: Contender External and Internal Chokes [message #32002 is a reply to message #32000] Sun, 29 June 2014 20:51 Go to previous messageGo to next message
cajuntec is currently offline  cajuntec
Messages: 1216
Registered: November 2009
Location: Williamsburg, VA
Top Contributor
Forum Admin
Good write-up Jim. Thank you for posting.
All the best,

If at first you don't succeed... buy newer / better equipment!
Re: Contender External and Internal Chokes [message #32071 is a reply to message #32000] Fri, 04 July 2014 21:02 Go to previous messageGo to next message
wwkmag is currently offline  wwkmag
Messages: 588
Registered: January 2013
Location: Maine
Senior Member

Well written Jim. I hope everyone takes notice, stay safe, Mike/WWK.
Re: Contender External and Internal Chokes [message #33356 is a reply to message #32000] Thu, 02 October 2014 18:13 Go to previous messageGo to next message
Maquinn is currently offline  Maquinn
Messages: 4
Registered: October 2014
Location: St Cloud, MN
Forum Newbie
Great dissertation here. One question: when you take out the shot shell tube, do you substitute a rifled model? Or just shoot 45 LC over the empty treads?

Re: Contender External and Internal Chokes [message #33361 is a reply to message #33356] Thu, 02 October 2014 23:08 Go to previous messageGo to next message
jamesgammel is currently offline  jamesgammel
Messages: 1711
Registered: August 2012
Location: Lovell, Wyoming
Top Contributor
When you shoot single projectiles you simply remove the choke. The threads are sufficiently oversized so that the bullet never touches or "scrapes" the thread. Before replacing the "choke tube".use a brass bore brush of a larger size (like 45 brush in a 44 40/44 in a 357, etc., to clean the threads in the barrel. #9 or other bore cleaner helps. with a 44 a patch over a 410 swab "rotated" in the threads works well to clean put the bore cleaner. A light touch of oil just before screwing in the choke helps as well. Turn the tube in until "snug", don't grief on it. The key's with two finger tightening is all that's required, no crescent wrench cheaters should be used with this. 45 threads could use a 50 cal bronze brush for thread cleaning.
They never made a "thread protector cap" like seen with suppressor threads, the barrels always have female threads, the tubes are male threaded and smaller in OD. Getting the pitch of the thread perfect for the rifling to mate up perfect and barrel independent would be a monumental task, and not really worthwhile or necessary. Let's not forget, these choke are tapered and designed for shot, so I wouldn't try shooting .410 rifled slugs through them. 45 colt and 44 mag regular pistol cartridges should be used with the chokes removed.
Re: Contender External and Internal Chokes [message #47171 is a reply to message #33361] Thu, 10 March 2022 10:35 Go to previous message
gemihur is currently offline  gemihur
Messages: 291
Registered: March 2012
Location: Ridgelines of Virginia
Forum Regular
'They' never made a "thread protector cap" like seen with suppressor threads but I ran into a barrel a few years back that had been listed on Bellm's site, back when he permitted sellers to post ads.
It is a rare find and I've love to have a few made to share with fellow shooters.
Every time I approach a machine shop with lathe operators, as soon as I show them my part to duplicate they freak out because of the stigma assigned to gun part manufacture and decline the project!
I still respect Jim's perspectives and hope that someday I can offer a small part of his vast knowledge of these little break-actions.
Thank you, Mr. Gammel.

Think twice...shoot once.
Previous Topic: Contender Barrel Diameters
Goto Forum:

Current Time: Fri Oct 07 07:58:54 EDT 2022