Mixing/matching AR parts brands

[uneven]

Hey everyone, was thinking - most shelves are empty for any AR hardware anyway, but from a newb how wise is it to mix brands for a complete kit? For example would a Spikes upper kit fit with another brand receiver and an Armalite lower or could that cause problems?

 

[Boom Boom]

They are designed to be interchangeable. Modularity is a fundamental aspect of the AR-15 platform. Beware of the low-end stuff, though, since their tolerances (that is, lack of) tend to suck.

Also be aware that some stuff differs from AR-15 specs. Bushmaster Carbon 15 5.56mm uppers are one example, with a non-standard BCG.

 

[Blu Falcon]

Of the 4 ARs I've built (mixing/ matching components from different manufacturers) I haven't run into any problems with regards to fitment or compatibility. As stated above, the AR is a very modular platform, but some components may not play well together. Best to list what parts you've got in mind to assemble and post here to see if anyone has assembled something similar (I haven't used a Spike's upper or Armalite lower). There's not a lack of AR gurus on this forum.

 

[-Z/28-]

Be careful with the stock assembly. There are two types; Mil-spec and Commercial-spec. The tube and stock must be the same spec.

 

[uneven]

Thanks all, great advice. I know it varies, but are there any parts kits I should avoid? Picked up a Tactical Machining receiver, the Spikes upper kit and the Armalite lower assembly kit so far. Any suggestions welcome, been planning this project for a long time and feel now might be my last chance to build it.

 

[Boom Boom]

Spikes and Armalite parts are generally fine. Expect minor fit issues. Where it tends to get iffy is with off-the-wall brand names and/or specialized parts (like the super-cheap polymer stripped lowers).

 

[Ab_Normal]

Be careful with the stock assembly. There are two types; Mil-spec and Commercial-spec. The tube and stock must be the same spec.

Not necessarily. Sometimes mil-spec stocks will fit on commercial spec buffer tubes very nicely and eliminate a lot of the rattle and slop if a mil spec tube were used.

OP - really the only way to find out about any fit issues is to go ahead and put everything together.

 

[EL1227]

Kit'ing guidance

Brownell's AR15 Catalog has some good mix'n'match guidance in the front for more than a few configurations with options ... and it's FREE.

Also, Gun Digest's 'Book of AR15' compilations by Patrick Sweeney also have build-your-own information along with a ton of other need to know information about the platform.

 

[Bolts Rock]

The only problems I've had over the decades are RRA match triggers not working correctly in Double Star lowers (it isn't a problem with the lower as Geissele triggers work just fine). The other "problem" is White Oak uppers tend to have a very tight front pivot hole and you need a punch to pop the pin, that's not really a problem and there is no slop in the fit when the rifle is closed up.

 

[Gbh]

I'm almost reay to assemble. I have a spikes lower, Danial Defense Lpk and Armalite M15A4 complete upper.

I'm trying to decide if I should go mil or commercial on the Magpul tube and stock. Is the extra cost between CTR-M and MOE worth it? I'm leaning towards mil since the rest of the rifle is made up of good parts but was looking for a experienced opinion.

Thanks

 

[ASM80]

I have a "mutt" rifle that was my first build. Everything went together fine and it's one of my best rifles. I have DPMS lower, no name upper, Precision firearms NiB BCG, Daniel Defense barrel, Spikes buffer, DD parts kit etc etc. I've ran it dry, wet, good ammo, bad ammo and havent had any problems out of it.

 

[ASM80]

I think the CTR only adds an additional friction lock. I have both, and both are pretty solid IMHO

 

[straightsilver3]

I have a Spikes Upper on a Bushmaster lower with mixed bushy and spikes Lpk works flawless As mil spec /commercial tubes go if you go with the Rogers super stock it will fit both

 

[Watkins87]

Does anyone know of anywhere still selling Lowers or Complete AR's? I just got the money for it and feel like a lost soul

 

[hacktracker]

Does anyone know of anywhere still selling Lowers or Complete AR's? I just got the money for it and feel like a lost soul

I think Gus at Accurate Pawn in Elkridge said he has a VERY large number of billet Adcor AR lowers coming in the very near future.

 

[jrumann59]

Mixing parts kits should not be an issue on standard forged and billet ARs, since more than likely the parts kits are probably manufactured int eh same place. Uppers and lowers I try to match, not a absolute but the slop is less when they come from the same manufacturer. I only us 80% of a lower parts kit. I usually replace the safety selector, the FCG and the FCG pins. I recommend staying away from stainless products in an AR, only in places where the finish can be worn a way, due to the galvanic properties of stainless steel and aluminum corrosion can become an issue. So stay away from SS pins, detentes, FCG pins, and anything stainless that threads on.