M14 Forum banner
1 - 7 of 7 Posts

·
Banned
Joined
·
3,722 Posts
Discussion Starter · #1 · (Edited)
I have two LRB M25 receivers that are not yet built, and just for fun I thought I would try a USGI trigger from another LRB built rifle in both of them. One I was afraid was NOT going in, and the other is a looser fit with a tiny bit of wiggle side to side. GI3 GI3 GI3 These receivers are consecutive #'s and this disturbs me! I can't quite get the
thickness of a business card in the gap.

Please tell me that the loose one is normal. I do not have feeler guages here but the play is a lot more than seems normal. I have a feeling LRB is going to see this receiver back at their shop.

I will post a video if it might help visualize. I just have no idea about the tolerances here, but I like the tight one better if you know what I mean!
 

·
Registered
Joined
·
1,166 Posts
If you're just fitting a trigger group to a receiver, no stock, it should be loose. I don't think you have anything to worry about.
 

·
Banned
Joined
·
3,722 Posts
Discussion Starter · #4 ·
Thanks y'all. I was kind of thinking that was the case but I got a little worried being that these receivers are very different in tolerances, yet are consecutive. I guess that means the CNC machines are not as perfect in calibration as one would think.

The more snug receiver / trigger fit seems more desireable.Will recoil not create a possible premature wear in the receiver / TG loose contact area? I see how the stock makes a difference, but what if the Sage I am putting it in (or any other stock) did not tighten it up? Then what, shimming? I wish everything fit perfect! DI2
 

·
Registered
Joined
·
504 Posts
FWIW, My lrb M25 receivers all fit pretty tight into my Sage stock. wouldn't worry about the trigger group fit until you have it in a stock.

if you look at trigger group picturs that have been used you will find peening on the side of the trigger housing. there was a thread about this the other week from someone getting a kit from CMP and it having a peened trigger housing. My one build from LRB came with a peened trigger group but it fits in all of my receivers just fine.
 

·
Registered
Joined
·
46 Posts
Thanks y'all. I was kind of thinking that was the case but I got a little worried being that these receivers are very different in tolerances, yet are consecutive. I guess that means the CNC machines are not as perfect in calibration as one would think.

All that CNC stuff happened before the heat treat I would think. Things move around when you heat them up and cool them down like that.
 

·
Banned
Joined
·
2,325 Posts
The more snug receiver / trigger fit seems more desireable.Will recoil not create a possible premature wear in the receiver / TG loose contact area? I see how the stock makes a difference, but what if the Sage I am putting it in (or any other stock) did not tighten it up? Then what, shimming? I wish everything fit perfect! DI2

Yes. it is more desireable to have it fit snugly. For accuracy as well, not only wear, which it will cause, given enough rounds downrange. After only a couple hundred rounds, you can remove the TG and see the shiny spots anywhere that the two are moving against each other. Usually the very top left corner of the TG in the front, on the left side where the guard is just below ,when latched. The mark will be above the guard. Opposite side also sometimes. This causes it to eventually loosen in the stock, especially with wood stocks.

When installing a TG in a new receiver, you should hardly be able to get it in the slot. This is if the TG is new and in spec, as well as the receiver slot. The park wears off after several installs and removals, but should remain tight.

As for shimming, I don't think so. I don't think it will hold up over time. I would rather peen the TG for a tighter fit. You might can have the trigger housing spline welded up with hard tack and machined or filed back down to fit, if it was protected from warping.
 
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top