Best lower to use?

[rickt300]

Getting around to building the A@ version I have been thinking about. I have two choices for the lower an Anderson and a Bushmaster both with low round count, under 200 with 5.56.

[Frontier Gear]

What do you mean by "best"? Both will work. Are you asking which one looks more like a classic A2? Or are you asking which one is better quality?

[rickt300]

Quality moreso. and I'm not really wanting to make an exact A3 version as I will use an adjustable gas block. Speaking of which who makes a good adjustable GB that is not super expensive.

[PVBoom]

Seekins does

[Bigs28]

Superlative arms adjustable gas blocks.

I did a ton of reading when I was looking at lowers and it seemed that allot companies got their forged lowers from the same place and just put their own logos on them.

[mdram]

they have to do final machining on the forged lowers

but some companies still make them for others

[worthen86ford]

[cb4017]

I've used a lot of lowers over the years. Probably the most problematic were ones from Olympic Arms. Currently in my safe are 7 guns or receivers from 4 different manufactures from LaRue to Anderson Arms. All went together and do the job with no issues. As worthen86 said, I would use the receiver that gives you the best fit to your upper.

[rickt300]

Anderson it is, fit is very tight and the trigger is better by far.

[PVBoom]

There are a couple philosophies (and more), regarding uppers and lowers. Its a quality upper that matters more, true to mate with the barrel which will impact accuracy the most.
The lower is the least important, it doesnt have the stress the upper does, so it comes down to style and weight. Of course, you want a tight alignment/lock-up with the upper and lower.
Otherwise its strictly your preference. You can get down to the minutiae. Flared mag wells? Adjustment screws for over-travel with the trigger, etc.? Pimping color palette. With the
world of sweet triggers out there, it a good matched set, and possibly weight that matter these days.

[LRRPF52]

I've learned to look at receiver sets, not individual receiver lowers or uppers.

They need to be considered together, rather than by themselves.

I've moved into preferring precision-machined forged sets, or billet sets after decades of basic forged sets.

For a military gun that needs to be easily shotgunned, I like forged sets that fit snugly, but still allow ease of push of the takedown pin.