(Very) basic question about mixing upper and lower brands

[Tuthmose]

Hello everybody,

I’m looking for some feedback on what is almost certainly the noobist of noob questions. While I’ve been shooting since I was a kid (so, so long ago), I’ve not owed an AR prior to now. I’m in the market, and after much research, I’ve reached the conclusion that the features I want on the upper and lower can only be had from two different manufacturerers. While I know it *should* be fine, “should” is no substitute for real-world feedback from folks with experience.

Specifically, I very much like the LMT MARS-L lowers for their ambidextrous controls, especially given the wife is a lefty. I’ve come to the conclusion that their monolithic uppers, while I’ve heard they are excellent, aren’t quite what I want. I’m leaning towards a Daniel Defense DDM4 M-LOK upper, especially for the longer handguards vs. the shorter LMT CQB or LM8 models.

So, the question – is there any reason I shouldn’t pair an LMT lower with a DD upper? Is there something about my proposed combo that is a bad idea, or am I on the right track? Anything to watch out for?

Thanks in advance for the advice and feedback!

[pointblank4445]

I've never had any problem mixing and matching Colt/LMT/BCM/DD interchangeably at all. To mind, I've had:
BCM upper/Colt lower
Colt upper/LMT lower
DD upper/Colt lower
Colt upper/DD lower
HK upper/LMT lower
HK upper/Colt lower
BCM upper/LMT lower

It 99% sure it'd be fine.

The only "big name" I've had not play well with a milspec upper was a Noveske lower

[Zane1844]

I think that’ll be a solid combo. I had no idea that lower existed. I don’t have a vast knowledge of what’s out there but I can’t think of any mil spec upper/ lower that won’t work together. You’re good with whatever you choose.

[markdh720]

You'll be fine. I've seen God knows how many combinations of uppers and lowers. The worst I've seen just had takedown pins that needed extra force to push them in and out. Once a few hundred rounds were fired through the rifles, the pins moved much better. And that happened on less reputable brands than DD, LMT, BCM, and the sort.

[pinzgauer]

Hello everybody,

I’m looking for some feedback on what is almost certainly the noobist of noob questions. While I’ve been shooting since I was a kid (so, so long ago), I’ve not owed an AR prior to now. I’m in the market, and after much research, I’ve reached the conclusion that the features I want on the upper and lower can only be had from two different manufacturerers. While I know it *should* be fine, “should” is no substitute for real-world feedback from folks with experience.

Specifically, I very much like the LMT MARS-L lowers for their ambidextrous controls, especially given the wife is a lefty. I’ve come to the conclusion that their monolithic uppers, while I’ve heard they are excellent, aren’t quite what I want. I’m leaning towards a Daniel Defense DDM4 M-LOK upper, especially for the longer handguards vs. the shorter LMT CQB or LM8 models.

So, the question – is there any reason I shouldn’t pair an LMT lower with a DD upper? Is there something about my proposed combo that is a bad idea, or am I on the right track? Anything to watch out for?

Thanks in advance for the advice and feedback!

One of my favorite carbines is an LMT lower with a DD upper.

[BCMNick]

My buddy has a MEGA billet lower and while waiting for the monolithic upper to come back in stock, he used a forged MEGA upper and they wouldn't work together. Idk if it was because of the billet + forged combo, or just a one off problem. Probably the latter. I have seen companies state, "_____ will not work with _____ lower/upper".

But to anwser your question, yes. You'll be fine!

[sig1473]

The only problem I've had to date is a Noveske Gen2 lower not play nicely with of all things a Noveske Gen1 upper.

[Jaysop]

I've put a few different uppers on my MARS lower. I decided to sell it because not all my lowers are ambi and I think it would screw me up in the long run.

Also I'll shamelessly tell you my lower is for sale on the EE.

No issues with fitment from Noveske, Colt, DD, or BCM

[Tuthmose]

Thank you all very much - I appreciate the help!

Looks like it's time to go shopping . . .

[Stugotz]

My buddy has a MEGA billet lower and while waiting for the monolithic upper to come back in stock, he used a forged MEGA upper and they wouldn't work together. Idk if it was because of the billet + forged combo, or just a one off problem. Probably the latter. I have seen companies state, "_____ will not work with _____ lower/upper".

But to anwser your question, yes. You'll be fine!

I spoke with someone in the industry, and was looking for a 2nd MEGA monolithic upper and he told me ZEV Technologies purchased and is merging with MEGA. He also said that no MEGA monolithic uppers are not being presently being produced so it may be a while before the MEGA monolithic uppers hit the market again. (A friend ended up buying a DPMS Lo Pro upper after giving up the search for a MEGA. We put together his new complete upper yesterday, and after taking a close look at it, I would definitely hold out for ZEV to ramp up production of the MEGA's. The MEGA (in my view) is hands down a much better upper receiver!

BTW, we took the DPMS upper and installed in on a MEGA lower he had and did not function with it. (The bolt would bind when you pulled the charge handle back and you had to pull the pins on the lower in order to get it to go back into battery). He is now going to be building another complete lower.