[mljdeckard]

I have a lower I assembled some time ago that had been collecting dust. I bought a CMMG .22 upper and slapped it on. After about 100 rounds, the trigger started hesitating to reset, it needed a slight nudge forward. When I got it home, I opened it up, and worked the hammer a little bit manually. It squeaks audibly when I work it back and forth. I'm thinking it just needs a healthy lube. Might it need more fitting than that?

[minutemen1776]

Since you say you built the lower, make sure that you've not accidentally swapped the disconnector spring for the bolt catch spring. The two are VERY similar, but the disconnector spring is a bit wider at one end. I had a mix-up once, and the result was a trigger that needed a little help to reset. It didn't happen at first, but started after a few hundred rounds. Could be your problem, too.

[mljdeckard]

Hmmmm.

[madcratebuilder]

Disconnector Spring - similar to bolt-catch spring, but identifiable because one end is wide than the other. Wide end goes down. Make sure hammer and trigger springs are installed correct, clean and lube.

[Friendly, Don't Fire!]

I have a Bushmaster and I had a problem with the trigger. Nearest I can figure, the holes for the two pins were not drilled quite perfectly, in line with one another. This would cause a very little binding of the hammer, and in many instances would result in a FTF.

I finally replaced the trigger with a Timney and replaced the two pins with ones that have allen screws on each end. I filed them to a length where the outer allen screws are just barely touching the left and right exterior of the receiver, allowing the pins to rotate if they want to.

This seems to have solved the problem I had with extremely light primer strikes out of the middle of nowhere.

Work the trigger several hundred times manually - dry (no oil, holding the hammer so it drops slowly) and carefully disassemble it, keeping each of the two pins oriented the way they were in the receiver and look for the bluing wearing off in certain places. My hammer pin had bluing worn off in such a way that I determined that to be the cause of my problem.

[taliv]

huh, this is a new one for me. let me know what it turns out to be

[-v-]

Had a similar issue with my lower. Following the comments, I am not sure if I also swapped the bolt catch and disconnector spring. Some light buffing on the disconnector surfaces to make them shiny fixed that issue and it has been 100% since then.

[IMtheNRA]

I had a similar problem after installing a JP trigger kit. Turns out, the trigger was a little wider that it should have been and it was getting squeezed by the sides of the receiver. Worked ok for a few dry fires, then reset began to get slow, and finally, I had to push the trigger forward to reset it. A replacement trigger from JP solved that problem.

If you're using some version of "anti-walk" pins, that could make the problem worse, since they seem to pinch the receiver.

[mljdeckard]

IIRC, it's a DPMS lower and LPK, which may or may not make a difference. I'll take it apart in the next couple of days.

[mljdeckard]

Well, it's not the spring. I think it came pre-assembled and it was correct. (But the bottom was jammed in a little bit crooked.) I'll clean, reassemble, and lube.

[Z-Michigan]

The hammer/disconnector junction is a sliding surface much like the trigger/sear. It may just need cleaning and lube. Or it may have a burr or some serious surface roughness causing your problem. The standard GI trigger is a dubious design as-is with that cheap stamped disconnector, and DPMS tends to have slack quality control and may have softer metal or more dimensional tolerances than a nicer brand.

I would clean and grease and see if that fixes it. If not I would disassemble and inspect the sliding surfaces for any burrs, damage, or obvious roughness.

Depending on your joy of tinkering you could also just buy an ALG QMS for $45 and forget about the DPMS parts.

[mljdeckard]

Well, I think I fixed it, I'll test it soon. The spring was the correct spring, but it was jammed in crooked. I used a tiny punch to force it in correctly, and it seems to have cleared it up.

The whole idea of this rifle is to have one that me and my soldiers can practice with. I already have an AR-10 with a Giessell trigger I'm spoiled to. I'm trying to UNlearn that one. :)

[mljdeckard]

Took it out on the ATV and shot a hundred rounds through it. No problems. (Other than a few FTFs from Wildcat .22s.)

[mljdeckard]

I didn't see the need to start another thread,

Now the trigger works fantastic, but the pin is walking out to the right. Is there any way to stop this besides using anti-walk pins?

[madcratebuilder]

Now the trigger works fantastic, but the pin is walking out to the right. Is there any way to stop this besides using anti-walk pins?

Double check you have the pins in the right holes. The hammer pin has a single groove in the center that captures the hammers J spring (ArmaLite uses a D spring) and the trigger pin has two grooves near the ends that capture the hammer spring legs.

http://i32.photobucket.com/albums/d37/madcratebuilder/AR15/hammerspring.jpg

You can get anti walk pins pretty cheap.
http://i32.photobucket.com/albums/d37/madcratebuilder/AR15/antiwalk.jpg

The anti rotation pins cost more and have the benefit of stopping any possible wear in the pin holes. They also well improve the feel of the FCG on many lowers and stop the pins from walking..
http://i32.photobucket.com/albums/d37/madcratebuilder/AR15/nantirotationpins.jpg