AR/M4 OEM Parts

[prepare]

Does anybody know who makes quality mil-spec AR components like port doors, forward assists, castle nuts, end plates, crush washers, and A2 bird cages. Obviously these aren’t major components but important nonetheless. BCM, Aero Precision, SOLGW, (many others too) sell them of course but are there any differences in quality or are they all made by an OEM supplier?

[crosseyedshooter]

There are definitely signs of multiple sources for small parts. It’s not a limited number of OEMs like the receiver forges.

I noticed differences in the ejection port cover from Aero Precision compared with BCM and Colt. The Aero part seemed thinner gauge and had a shiny black finish like nitride. The BCM and Colt are slightly thicker and have a dull phosphate-type finish.

I also have an A2 “mil-spec” flashhider from Brownells that’s a shiny black nitride finish and sharper edges instead of the tumbled phosphate finish on my Colt 6920.

[markm]

If you buy through BCM or get stuff from Colt via Brownells, you're fine. As far as where they're all made, I refer to my first sentence so I don't have to worry about those things.

[maximus83]

Yep parts are tricky to source as to the actual manufacturer. For small parts I mostly stick with a handful of places who carry reliable parts: BCM, Sionics, Geissele, Forward Controls Design.

Folks will say there are differences in quality. IMHO this might be true but is hard to prove unless people have been collecting comprehensive data on parts usage, round counts, failures, etc, or are doing scientific testing on the materials and durability under stress. As long as you get your parts from trusted sources, you should be fine and I doubt the differences are that great.

[everready73]

I know SOLGW uses Schmid lower parts and kns detents which are some of the best. I would trust that they're other small parts are gtg as well

Same can be said for Sionics and forward controls design. Should high quality stuff

I use Aero receivers occasionally but have had issues with some small parts in the past so won't use those anymore.

[alx01]

For small parts I have been very happy with White Oak Armament. They all seem milspec and worked fine.
Part price and shipping is better than most larger retailers.

[CLee0509]

There's definitely a difference in quality. The one time I ordered an Aero receiver extension kit, the castle nut cracked while torquing. I have never experienced this with BCM, Colt or VLTOR.

I also noted differences in Port doors and forward assists. The spec calls for the top "cap" on the forward assists assembly to be pinned (not just pressed) into place. Its a small detail that I believe is often overlooked. Off the top of my head the only companies I have seen do this in my own experience is Colt, BCM, Griffin Armament.


Edited to add:
The quality difference between my Colt charging handle vs your typical 7075-T6 standard charging handles from Aero was striking. Makes me wonder if the Aero wasn't made out of 6000 series and falsely labeled. I can feel the difference in hand and while in use. The coating is also much better and smoother on the Colt than any other standard handle I've seen

[prepare]

I bought an AP ejection port assembly and the door doesn’t seem to be quality. I also had one of their buffer springs break. Consequently I’m suspect of their stuff.

[maximus83]

I bought an AP ejection port assembly and the door doesn’t seem to be quality. I also had one of their buffer springs break. Consequently I’m suspect of their stuff.

Pretty much. IMHO their more recent upper/lower receivers are gtg, well designed and great value. However I avoid their small parts and assemblies, LPK's, their mounts, pretty much everything but the receivers. I have one of their ejection port assemblies that I plan to replace.

[prepare]

Pretty much. IMHO their more recent upper/lower receivers are gtg, well designed and great value. However I avoid their small parts and assemblies, LPK's, their mounts, pretty much everything but the receivers. I have one of their ejection port assemblies that I plan to replace.

Wonder who they source ejection port assemblies from? You wouldn't think too many places make them?