How To Build An AR-15 Upper
BY Herschel Smith
1 year, 2 months ago
This is a followup to the post on How to Assemble an AR-15 Lower. I told you I’d link it when they came out in print with it.
Recoil: How To Build An AR-15 Upper.
You can’t just throw your upper in the vise without damaging it. There are a few ways to skin this cat, but I recommend a reaction rod. Geissele makes a good one, as does Wheeler. I use the Real Avid one and have done so for years. These are nice because you have options for mounting and turning the action as you work. If you want something cheaper, a vise block that clamps around the action is only $20 normally and works well. It does limit you and makes assembly a little harder, but it’s cheap.
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Technically speaking, the only correct lube is AeroShell 33MS. That said, I use White Lithium grease. You NEED to use grease on the threads for the barrel nut and muzzle device, or you risk ruining them. When selecting a grease, the major thing you need to avoid is a grease with graphite or copper in it. AeroShell 33MS is the mil-spec grease, and I would assume it’s the mil-spec grease for a reason, but I honestly don’t know what that reason is.
I’ve looked, I’ve asked, and no one has been able to tell me why it is the mil-spec other than that it doesn’t have graphite or copper in it. Personally, white lithium is a lot more universal, and buying a tube of that makes more sense to me. I started using white lithium based on the advice of a major brand, and I’ve never had an issue, even if it isn’t “mil-spec.”
He talks about do’s and don’ts, torquing specifications, and other tools you will need.
Frankly, I don’t know how much I’d trust any tool except Magpul. Also, he doesn’t say much about parts (in terms of recommending specific brands). I won’t ever replace a BCG in any of my guns without it being a BAD (Battle Arms Development) or a charging handle without it being a Radian Raptor.
On September 2, 2023 at 12:37 am, Steve R said:
AeroShell 33MS is a moly disulphide bearing high temp grease. We used on on the fuse pins of 737 engine struts.
On September 2, 2023 at 10:16 am, george 1 said:
One thing many people do these days is to “lap” the receiver face. Many say it isn’t needed but I always do because it is easy and does not take much time. You need a tool to do it, a receiver face lapping tool. You also need some lapping compound. This is to take off a slight amount of material on the receiver face that may be high to make the barrel fit more flush to the receiver. Lots of videos out there that show how to do it.
There are also methods to bed the barrel of an ar15. If the barrel fit is not tight, that is the extension slides into the receiver too easily, many bed the barrel with shim stock. Again, many videos and instructions out there to see how this is done. I have done this on a few uppers but now I always buy uppers with barrels that already have a tight fit. The BCM uppers that I have used have always fit the barrel very tightly. So that is what I use now. The BCM uppers that I have used always mic about .9950. YMMV.
Another thing that I do is is to use some high temperature thread locker on the outside of the barrel extension just before I install the barrel on the upper. Some manufactures do this for completed uppers and some don’t. I think it fills in any voids that might exist. May or may not be necessary it is just something I do.