Building an AR15 Upper

[matt]

A guide from Midway on how to put together an upper from parts:
http://www.midwayusa.com/midwayusa/StaticPages/pdf/Instructions/AR-15 Varmint Rifle Instructions.pdf

 

[matt]

The barrel in this set of instructions is headspaced by the manufacturer. Is this typical? Or do you Typically have to headspace the barrel yourself?

 

[Gammon]

The barrel in this set of instructions is headspaced by the manufacturer. Is this typical? Or do you Typically have to headspace the barrel yourself?

Headspace in an AR is controlled by the bolt and the barrel extension. Installing a barrel in an upper has no affect on headspace.

 

[7.62x39]

Although what gammon posted is technically correct, it may be a Little confusing to the OP. Whenever you buy a complete upper (either W or W/O a bolt and carrier) the Assembly should be correctly headspaced. As gammon mentioned this is accomplished with the barrel extension, so it should be correct no matter what BCG is used.

 

[MichaelJ]

Thanks. I will be building an M4gery with my NES lower but I am trying to get all the AR info I can.

 

[cdkayak]

As stated above you shouldn't have to worry about headspace with a new barrel and new bolt. That being said, I do check with a GO and NO-GO gage any time I set up a new rifle or change out a barrel or bolt just to be safe.

 

[matt]

As stated above you shouldn't have to worry about headspace with a new barrel and new bolt. That being said, I do check with a GO and NO-GO gage any time I set up a new rifle or change out a barrel or bolt just to be safe.

So the ring at the end of the barrel above is set by the factory so that the headspace will be corrrect? Sorry, just want to be sure.

Seems a go/nogo gauge set would be cheap insurance to make sure the headspace is correct as you suggest though.

Thanks for the replies guys,
Matt

 

[cdkayak]

Yes, the barrel extension should be installed by the manufacturer to the correct headspace. I haven't run into one that was out of spec, but 5 or 6 barrels is a pretty small sample set. I picked up the gages when putting together my first upper just to be sure.

It is also indexed to the gas port under the front sight base.

 

[7.62x39]

Seems a go/nogo gauge set would be cheap insurance to make sure the headspace is correct as you suggest though.

Absolutely. I've got Go, No-Go and field gauges in 7.62x39, 5.45x39, 5.56x45 and 7.62x51. I don't take anything for granted.

 

[glennv]

What about if I am pulling the barrel and installing it on a new stripped upper and reusing the same bolt? The bolt and barrel are from the same rifle.

 

[LoginName]

What about if I am pulling the barrel and installing it on a new stripped upper and reusing the same bolt? The bolt and barrel are from the same rifle.

The head spacing will be fine.