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Ordering my AR10 lower this weekend if my truck doesn't cost me an arm and a leg, was going to get started on a 5.7x28 build and get both lowers at the same time. My question, what parts does a 5.7 need that are different from my 5.56's? BCG, Upper, Barrel? Anybody done this?
Buddy of mine had one and it's sweet. If ammo wasn't so expensive and hard to find I'd buy one myself. I know they sell them as a compete upper, but I'm not sure about the buffer.
Pretty sure just about everything in the upper is pretty different. The uppers do just drop on a standard lower.
Might have trouble finding magazines if that plays into your decision.
They use a different upper then a standard ar.....you just buy them already assembled, slap it on a standard lower and then swap out the buffer and your good to go. They make blocked 10 round mags, but standard magazine capacity for the fnp90 mags they utilize is 50 rounds.....why go for a lower power more expensive round (then 5.56) with a 10 round mag?
Edit....the one thing that is compatible is 5.56 muzzle attachments, that's all I know of. you can't even change the rail/handgaurd since it is built on a monolithic upper.
Have to check on mags, put the Masterpiece Arms pistol on layaway, so will need to have ammo for that, might as well need it for something else also. Haven't bought factory ammo in years, reload all my calibers, everybody says this is a finicky round, so will enjoy the challenge. Only .7 grains difference between start and max. Uses the same 224 bullet as our AR's, just have to use 40 grain. My big question is pressure for the gas system, the AR's I've built have had cycling problems in the past because I was loading for 223 Remington instead of increasing the pressure to 5.56. Think the buffer would have to be lighter to cycle with reduced pressure.
I'm not positive but I think it is blowback operated.
Yeah, I was typing when GunsRBad posted, thought I could build one just like the others. May have to rethink, gonna get my AR10 lower ordered though.
Yeah no gas assist on it either, and it uses a heavier buffer. If you weren't so far away I'd offer to let you shoot one, I know someone who has one ;)