LW-15 polymer lower with CMMG upper

[cc56]

So I bought a LW-15 lower and am trying to put on my CMMG upper. The front pin goes in but the back one won't. Has anyone else had this problem? If so what did you use to "shave" down the lower? Thanks for the help.

[joker70]

I have the same exact set up and while it is very tight, I was able to connect the upper. In fact, my Colt 5.56 upper is even tighter. Try a little lube first.

[tba02]

Check the trigger width. Some require a blow back hammer swap.

[the_t0ny]

I have the exact same setup as you and I am experiencing the same problem, it's a very tight fit and I have to slightly force it in but it works and fires fine so far. Another problem I notice is that when my upper is on the LW15 lower, for some reason the charging handle is harder to pull back and it almost feels like it grinding on the upper.....

[OC_Gunner]

I'm planning a similar build once I get my lower (not yet ten days) and once the tactical solutions upper is back in stock. This seems to be common. Since I am new to this, can someone explain what a blowback hammer is please?

[joker70]

I'm planning a similar build once I get my lower (not yet ten days) and once the tactical solutions upper is back in stock. This seems to be common. Since I am new to this, can someone explain what a blowback hammer is please?

It's an aftermarket hammer that is thinner than the New Frontier hammer. The thicker hammer might be too wide for some uppers. I don't know about the Tactical Solutions upper, but it's not an issue with my CMMG Evolution.

[OC_Gunner]

Do you like your CMMG upper? Feel that it is well made and shoots accurately enough?

[JackRydden224]

I actually have a problem with my LW-15 lower and CMMG upper. When I squeeze the trigger I hear a click but nothing shoots. Perhaps the hammer isn't connecting?

[OC_Gunner]

Yeah I'm starting to wonder if it's worthwhile to build this thing. Seems like it might be more problems than it's worth.

[Speedpower]

The blow back hammer has been designed to be slightly narrower, resulting in better compatibility with dedicated AR-15 .22LR and 9mm uppers.

This is how it looks!

[JackRydden224]

The blow back hammer has been designed to be slightly narrower, resulting in better compatibility with dedicated AR-15 .22LR and 9mm uppers.

This is how it looks!

Yes, better compatibility, but I don't think that means the standard hammer that comes with the LW-15 lowers are incompatible with CMMG uppers right?

Just trying to figure out what is wrong with the rifle haha....

[paintballdad]

I had thought about picking up a LW-15 lower to mate with my CMMG Evolution upper for a lightweight AR-22. But wiith all the issues (although they seem to be minor) i'm seeing in this and another thread, i think i'll stick with my built Mega lower since the AR-22 is shooting fine now.

[joker70]

Both my New Frontier lower and CMMG upper are brand new. I'm guessing they are both the latest generation and have had all the bugs worked out of them.

Do you like your CMMG upper? Feel that it is well made and shoots accurately enough?

I like it a lot and being an aluminum receiver helps to make it feel solid. I am amazed at how quiet it is. Firing it sounds like an AR15 being charged. It does feel gritty when you charge it but that's because the slides are parkerized. I figure they will polish themselves in time. After ~300 rounds I only had 3 FTF so I won't do any home gunsmithing at this time.

I don't know what your criteria for accuracy is but at ~100yards I was able to hit a 12" target easily shooting prone with bags and a 4x scope. I am a new shooter so I was not getting 1inch groups like you see from all the interweb snipers

[wellfedirishman]

I have a New Frontier lower and CMMG 20" dedicated 22LR upper and they work perfectly together. Put about 300 rounds through the setup last Saturday without a hitch.

The New Frontier lower I have is recent production and has been very reliable.

[cc56]

So I lightly filed both sides of the lower and have a tight fit between the upper to the lower. Now when I try to charge it after "firing" it is a realllly tough pull. I figure I will have to sand the hammer a bit. I need to fire it tomorrow to see it it works or not.