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Tight M4 trigger group


Sigfla
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I noticed my new M4 was having some slight hangups while hand tacking the bolt with a shell on the shelf. I read through the forum and found another user with a similar problem from 2009. My gun is brand new so I am not too worried about it as I believe the issue is simply the unworn finish on the Benellie shell stop and possibly the carrier release lever on the trigger group. Both of mine have a rough finish on them currently. If it continues to be an issue I will likely buy a GG&G unit and give it a slight polish and install. I like the larger button anyway. My main concern is how tight the entire group itself is. I have seen many videos of people removing their trigger groups without any real effort. Mine is very tight and requires a bit of pull to get it out. Reinstalling it also requires some effort. Is this normal?

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I will try it. I have a new Mesa coming so I have to do it anyway. I am not sure its the stock though b/c it seems to be tight on the sides not front to back. I actually twisted my stock slightly the last time I took it apart to look inside and found that the takedown pin hole aligned easier when I dropped the trigger group back in but the side tightness was still there. I think its the polymer trigger guard to be honest. Its not a huge issue by any stretch. It just takes me longer to get my gun apart and back together due to its sticking. I just thought it might have been a contributing cause of my bolt sticking back while trying to hand rack a round in off the shelf. 

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29 minutes ago, StrangerDanger said:

You’re pressing the bolt release while inserting the trigger frame right?

Yes. I can press it during removal and it takes slightly less "pull" to get it out OR I can just pull harder and it will come out (usually with my thumb giving an assist along the receiver). Installation is done while pushing the release button. The trigger group is tight at the rear closest to the stock. As I said its tight on the sides it fits better front to back. If I am a little off of the takedown hole its not a huge hassle to get it lined up but even that takes multiple tries to get right (2 or 3), eventually it all lines up. I feel my trigger groups casting is rough and I have some edges that are a little wide which is causing the tightness.  

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I just grabbed the gun and a few shells along with my flashlight. The only reason why this is a concern is if I choose to leave a round on the shelf with an empty chamber for safety. It is 100% the tension of the shell stop jamming the round from lifting. I do not know if this is going to be an issue under firing as the gun is new but I doubt it will bc the amount of tension here is very light. Its just enough to hold the shell from lifting up away from the back of the shell stop.

Either a stronger carrier lift spring would fix it (pushing the round up past the shell stop with more force), a light polish on the side of the shell stop (allowing the round to move more freely), or a lighter shell stop spring (not allowing it to push against the cartridge rim so hard). I used some older Federal buck with a rough cartridge rim and some newer stuff with a nice shiny smooth rim. Both got jammed up into the back of the shell stop without lifting up off the carrier with enough force to chamber. I assume the cartridge rim pushes against the shell stop allowing the carrier to move forward. If I decide to polish it would be light as thats the easiest fix I can think of. I am hesitant to try and stretch my carrier lift spring any to see if that gives the round more upward force.  

Edited by Sigfla
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I just spent 30 minutes trying to wrestle my trigger back in after I messed with unscrewing the stock. It was tight but much easier to seat without the stock in the way. With the stock installed it was a bear to get it adjusted just right to allow the trigger group to seat itself to the rear. As far as the shell stop I went ahead and ordered a new GG&G unit. I like the larger pad anyway. Hopefully the new shell stop and spring that comes with that unit will fix the issue. However, I still believe I have a slightly oversize trigger housing. I am not messing with it again until I get the new Mesa Stock and then I'll see how it fits. 

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The polymer trigger frame might need some minor fitting at the rear where the stock is kept aligned. Sometimes they’re too tight of a fit. I wouldn’t recommend doing any filing unless you are skilled at such things.
Another work around would be to replace the polymer frame with an A&S Engineering one. 

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48 minutes ago, StrangerDanger said:

The polymer trigger frame might need some minor fitting at the rear where the stock is kept aligned. Sometimes they’re too tight of a fit. I wouldn’t recommend doing any filing unless you are skilled at such things.
Another work around would be to replace the polymer frame with an A&S Engineering one. 

I think that may be my next move down the line. I didn't want to have to mess with it but its for sure something like that which is going on. The polymer molding looks tough as nails though and very high quality. I went ahead late night and manned up with a tiny bit of Flitz and took the finish off the shell stop where it touches the case rim. I figured if I messed it up I have a new one coming anyway. Anyway I was very light with it and just polished it up a little bit. The first round off the shell carrier while racking the bolt hung up again but it was much higher up in the chamber and "almost" made it. The next 10 fed in no problem. I used a couple of different rounds as well. The only thing I haven't tested was a slug. This is with the barrel pointing straight up as well so its all bolt and spring lifting and feeding the round without any help from gravity.  

Its been a bit of trial and error to figure out why the gun is doing this. I am so used to a lot of recoil spring tension ramming rounds home that this had me wondering what was going on. Now I am curious once my new unit arrives from GG&G how the shell stop spring tension is on that one. Once I removed mine I realized that its pretty strong and I think that contributed to the issue most of all. Loading rounds requires A LOT of force into the magazine and I have a pretty solid click once they go in. Shotguns are kinda new to me even though I own and use many, I have a lot more experience working on my handguns and rifles so I am exploring everything with this one trying to figure things out. I also have no other M4 to compare since I bought this one brand new sight unseen. 

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