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TVegas wrote:

mr1337 wrote:I'll add one caveat to the "all parts work with all AR-15s" mantra. Pay attention to the type of buffer tube that you get with your lower parts kit. There are two types: commercial and mil-spec. They are slightly different size, and the size will determine what butt stock you should get. There are commercial stocks and mil-spec stocks that fit onto their respective-sized buffer tube.

I've seen that. Is there any practical difference between the two?

Not that I know of, but I'm no expert.

A quick google search produced this page:

http://www.brownells.com/.aspx/lid=1644 ... ffer-Tubes

In which Brownells explains that they differ due to the manufacturing process. Commercial buffer tubes are made with a less expensive process.

I'll add one caveat to the "all parts work with all AR-15s" mantra. Pay attention to the type of buffer tube that you get with your lower parts kit. There are two types: commercial and mil-spec. They are slightly different size, and the size will determine what butt stock you should get. There are commercial stocks and mil-spec stocks that fit onto their respective-sized buffer tube.

TVegas wrote:From what I've seen, it looks like there are lots of good kits for this type of build (assembled uppers and parts kits for the lower).

I would rather have a matching upper and lower, but does it make much of a difference to mix and match brands between the upper and lower?

I think you mentioned PSA. Just get a stripped lower and a LPK (lower parts kit). The LPK will include everything that goes into the lower receiver.

It does not matter if you mix and match brands for upper & lower. That's the great thing about the AR-15. It's modular in that manufacturers will make parts that are compatible with all AR-15 lowers.

Myself, I got a blemished PSA lower (which didn't actually have any blemishes), and a LPK with Magpul grip. I assembled the lower myself and got a complete upper from Karri's Guns (online store).

The only thing you need to have shipped to an FFL (or purchased at an FFL) is the lower receiver itself. All the other parts can be shipped directly to you. In fact, it can be cheaper to do it that way because you will only be paying the excise tax on the lower receiver, not the assembled firearm as you would if you just bought a complete AR-15 off the shelf.

Build your own lower. It will give you a lot of insight into how the weapon operates. The upper, you can just get a complete upper. I had to do this as I do not have a vice to torque the barrel.