I have bought an A3 forged flattop upper receiver assembly and a 20"bull barrel in .223 from separate shops. How do I check or set the head spacing I read so much about?

You might want to look on AR15.com under the build it yourself forum if you have not looked there. Lots of information there on headspacing.

Pull the bolt/bolt carrier assembly. Remove the bolt nose ejector, clean the chamber, install a .223 no-go gauge into the chamber and push the bolt/bolt carrier closed. The lugs should not fully engage. The bolt carrier should protrude from the back of the upper receiver.

All AR15 parts are made to a certain specification. All the parts should readily interchange. This is why they are so popular. All the bolts are made to rigid specifications. There is a chance you can get some out of spec bolts or barrel exttensions, but I highy doubt it. Go over to AR15.COM and look around. Great info there and many knowledgeable people.

Thank you to all. I will check out AR15.com

quote:

Originally posted by starmetal:
Go over to AR15.COM and look around. Great info there and many knowledgeable people.

What exactly are you saying?

I' pretty sure there is one or two around here who might know a thing or two about them. Heck they can't be that difficult.

quote:

Originally posted by starmetal:
All AR15 parts are made to a certain specification. All the parts should readily interchange. This is why they are so popular. All the bolts are made to rigid specifications. There is a chance you can get some out of spec bolts or barrel exttensions, but I highy doubt it. Go over to AR15.COM and look around. Great info there and many knowledgeable people.

It may be that all parts should interchange but anyone who does not confirm this is an idiot.

quote:

Originally posted by starmetal:
All AR15 parts are made to a certain specification. All the parts should readily interchange. This is why they are so popular. All the bolts are made to rigid specifications. There is a chance you can get some out of spec bolts or barrel exttensions, but I highy doubt it. Go over to AR15.COM and look around. Great info there and many knowledgeable people.

Just because they are supposed to doesn't mean that they do. Assuming that they do can lead to major screw-ups.
All AR bolts do NOT headspace properly in all AR barrels and Barrel extentions - trust me on this.
And just because they might Headspace does NOT mean that they will function properly.

Get a set of Headspace gages............................DJ

quote:

Originally posted by starmetal:
All AR15 parts are made to a certain specification. All the parts should readily interchange. This is why they are so popular. All the bolts are made to rigid specifications. There is a chance you can get some out of spec bolts or barrel exttensions, but I highy doubt it. Go over to AR15.COM and look around. Great info there and many knowledgeable people.

Sir, we have a saying in East Texas - "There's always a difference between 'supposed to' and 'is'." Everyone ought to check to the headspace when assembling any firearm...even if its supposed to fit together like an erector set.

BTW - I applied for membership at AR15.com about six months ago so I could ask a couple questions and I'm still waiting on approval. I wonder what the hold up is?? Reckon they found out I'm more into Mausers and FALs and think "tactical" is a joke?

If you mean you registered to login in, that is pretty much automatic. Doesn't take a commitee meeting to get approved. But they send an email back when you submit with a hot-link you have to open to activate your registration. If you skip that step, it will never register.