SmallCaliberCentral

I just bought a new upper for my colt AR, it is a DPMS in 223 Rem., it didn't come with the charge handle, bolt or carrier. Can I just use my group from the colt upper? Never thought about it until I just read about a "head spaced bolt". I have it assembled and a couple different loads of 50 gr. Vmax under some H335 ready to test. Kinda new to the AR platform.

I won't swear to it, but generally, you want to have the bolt headspaced to match the barrel/nut assembly. The rest of the bcg will work fine though.

When I did the same search, it amounted to, no it doesn't matter. I think if you go on RRA's site, they sell the same BCG for .223, .204.

My son did a lot of armorer work with 82nd airborne, and he said they just slapped 'em together (the 5.56's), and that's that, no bolt/barrel matching or headspace measuring.

I bet though that there are a few accuracy guys that would argue to the death that in an AR15 platform, tweaking the headspace (at the bolt I guess?) and gets more accuracy. 'Probablys some with lots of trophys, etc. that would argue otherwise...

FWIW if you feel a little wishy-washy on the subject after all the brethren here chime in, ar15.com and snipershide.com are good sites get info on that...

I think your most likely right. I see both sides on the matter myself. Heck, try it and see if it will manually cycle without and with a few rounds. If it does, shoot it a couple times and see how it shoots.

There is no adjustment for headspace on an AR. It either headspaces correctly or it doesn't. If it doesn't, you need to swap bolts.

Chances are it will headspace properly, but you really need headspace gauges to be sure.

+1 on gauging it... I should have said that. Ie.:

1) For AR-15, the .223 bolt is the same one used for .204.
2) When you assemble an AR-15 upper, there is no (conventional) headspace adjustment.
3) However, its always BEST to confirm headspace with a headspace gauge...

'Cheap insurance that you assemlbed correctly, and that none of the parts left the supplier with "oops!" attached.

Thanks guys.

loader her up with 25 grains of 335 and 25 gr. Vmax....shot well