Want to build an AR

[MaryB]

My gun dealer has all the parts to check head space and the reamer if it is short. He has a lathe on order to take care of barrel length issues for to long

[Hmac]

*sigh* He should check the headspace if he's worried about it, or especially if he uses a bolt or barrel of less-than-stellar quality. Cheap enough at some gunsmiths. He could even throw a go-nogo gauge into his tool budget for about $80 and Do it himself.

OP, speaking of tool budgets, be a little careful there. Everyone always mentions an Armorers a Tool. Many of those are crap, and good for maybe one use, and they're only really helpful if the rifle you're building uses a conventional barrel nut/delta ring assembly (plastic snap-in handuards and non- freefloat barrel). If you choose a rail system, they'll have their own barrel wrench usually. Consider a HammerHead tool. As to receiver clamps, most represent a good chance to twist a good receiver out of spec. Consider a Giessele reaction rod, use for barrel and muzzle device.

Don't forget a good click-adjustable torque wrench that'll go 80 ft-lbs.

[shooter115]

If you're going to assemble your own upper, I would highly suggest you verify the chamber to be in spec. Now out of the dozens or AR's I've screwed together, only one head spaced just on the long side and the owner didn't want to deal with fixing it.....whatever. The gun still shot very well and functioned flawlessly, but if it were mine.... I definitely would have fixed it.