jim Posted June 3, 2008 Report Share Posted June 3, 2008 Is the front sight on a Colt 1921a threaded on or pressed and pinned? I want to take the compensator off of my 21AC and put on a 21A sight. Link to comment Share on other sites More sharing options...
gijive Posted June 3, 2008 Report Share Posted June 3, 2008 The front sight on a 1921A is not threaded, it is pressed on and pinned. Link to comment Share on other sites More sharing options...
Sig Posted June 3, 2008 Report Share Posted June 3, 2008 jim Have you considered buying a 21A barrel/front sight along with the tools to install? michael Link to comment Share on other sites More sharing options...
jim Posted June 3, 2008 Author Report Share Posted June 3, 2008 No, too expensive. I wonder if I could just get a M1/M1A1 sight threaded and nicely blued. I wonder if the threads would be noticable? Link to comment Share on other sites More sharing options...
FireMerc Posted June 3, 2008 Report Share Posted June 3, 2008 You could take a M1/M1A1 front sight and slide it over the threads with a bit of 2 part epoxy. It will be a good fit, if you want to remove it, it will come off with a bit of heat. It will look fine, actually you will have to look close to see that it is not original. Link to comment Share on other sites More sharing options...
gijive Posted June 4, 2008 Report Share Posted June 4, 2008 FireMerc, I think it may depend on whether Jim's gun has an original Type 1 compensator or the later Type 2. The thread pitch was different on both. The earlier guns just removed the ring sight and threaded the boss for the compensator. The second type used a thicker boss that was threaded, identical to the WWII guns. There may not be enough available metal for the WWII ring sight to fit the original threaded boss. I am not a machinist, so this is just a thought. I'd investigate the matter with a competent Thompson gunsmith before I removed an original Type 1 compensator from a 1921 Model gun and tried to epoxy on a WWII ring sight. I wouldn't want to inadvertantly destroy the original threads on the Colt barrel. Link to comment Share on other sites More sharing options...
jim Posted June 4, 2008 Author Report Share Posted June 4, 2008 Mine has a type I compensator(no markings on it). I emailed PK and he says he's done it before but you can't just thread an M1/M1A1 type sight. I'm assuming he meant that the sight has to be made from scratch. I asked him but have not heard back yet. Link to comment Share on other sites More sharing options...
Bob Posted June 4, 2008 Report Share Posted June 4, 2008 Sounds like fun, maybe I'll do mine too! Link to comment Share on other sites More sharing options...
PK. Posted June 4, 2008 Report Share Posted June 4, 2008 The inside diameter of a press on sight is to large for either the 5/8†thread used on the first model, or ¾†threads used on all subsequent Cutts style barrels. A standard ring sight can be modified, but a sleeve must be installed in the sight to provide enough material to form the threads. I think this is your only option for the type 1 barrel, but FireMerc’s suggestion would be a very inexpensive adaptation for the others, if you can accept it. Link to comment Share on other sites More sharing options...
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