Colt AR Trigger Help

[smokemjoe]

Do any of yous have a Colt AR 15, The reason is I put the Hammer, Sear and Trigger in a Semi Auto rebuilt Sten rifle, 17in.barrel and made to ATF specs. Sometimes it will not reset the trigger. It seems like at some point there isnt much pressure on the return spring for the trigger. On the Colt Rifle is there alot of spring pressure all the time. When it dont reset I have to pull the bolt back and then its okey, Thanks for reading. Joe

[danski26]

Joe,

AR-15 "semi-auto" do not have a sear. I'm guessing you mean the hammer, trigger and semi-disconnect which you installed in a "sten rifle". I'm not familiar with a Sten sub gun but can give you a few places to start looking for a problem.

The disconnet which catches the hammer during recoil is a bit sensitive to recoil velocity of the hammer and bolt. If the hammer gets pushed back too fast the spring tension will not be enough to catch the hammer before it starts its trip forward. Slow the velocity by one of several ways including more wieght on the bolt or bolt carrier,smaller gas ports "if the sten is gas operated" or lengthen the gas tube/barrel port again if it is gas operated. It also can be slowed by careful handloading but I would use that as a last resort because you are compromising ammo preformance.

Look at the engagment of the disconnect and the hammer making sure there is enough bearing surface and at the correct angle. New springs are a cheap investment if they solve a problem also.

Let me know if you want some "spare" parts to try to swap out to see if your parts are the problem. I probably have stuff laying around that you could try before you go out and buy a bunch of new parts.

Pm me if you have more questions I know the AR system can be frustrating......i work with them for a living.

[imashooter2]

It resets when you pull the bolt back manually. Is it as simple as the Sten short stroking?

[sharps_74]

It resets when you pull the bolt back manually. Is it as simple as the Sten short stroking?

That's kind of what I was thinking. Sometimes Stens will short stroke with the wrong ammo. They seem to like it hot.

[BlurredEdge]

Do you have a copy of the acceptance letter from the ATF verrifying that this is a legal way to do a semi sten build? I've been trying to find a copy before I actually do mine. I do WWII reenacting so there are always people checking paperwork for Class 3's and making sure things are on the up and up.