bolt/bolt carrier interchange headspace question

[R4 fan]

I checked through the archives and I can't seem to find anything that answers my question.

I just bought a new DSA SA58. Say I wanted to swap the bolt and bolt carrier out for a different one, which is also new. Would the rifle have to be re-headspaced? Can you interchange the bolts and bolt carriers between rifles considering the fact that they are all new? How about switching used components?

I want to have some bolt and carrier combos as spares, so can I just replace them whenever I wish, or does that constitute having the rifle re-headspaced again too? :confused:

[ August 25, 2001: Message edited by: gary.jeter ]

[panchop]

in a related vein, can you use a sandcut carrier with your originial bolt and if you do do you need to re headspace.

[W.E.G.]

There is some previous testing in this regard.

See: http://www.l1a1.com/cgi-bin/forums/ultimatebb.cgi?ubb=get_topic&f=10&t=000162

[R4 fan]

Thanks Gary. That's the post I was looking for.
:cool:

[ricochet]

There was really good info in that post. I just pulled out several bolts, inch and metric, and I got a total of .003", which would still be considered safe if you headspace tight when building.
Either way, I will always recheck headspace if I change the bolt. I have read where some WECSOG and wanna be armourers filed on the bolt for headspacing. As we say at work, it is better to err on the side of safety. I don't want to eat a bolt. :eek:
With 50,000+ psi that close to my face, I want to check it. :)
Rechecked after reading Ted's post, and I still had .003" difference from my tightest to loosest bolt (out of 14 checked). Maybe a fluke, but a fluke is sometimes normal in surplus stuff. :rolleyes:

[ August 26, 2001: Message edited by: ricochet ]

[EMDII]

Australian 6202075
8.580 cm

RA (South African) 0649/17335
8.580 cm

Enfield 58 A135648
8.581 cm

Enfield 58 A9219
8.580 cm

StG (FN-built) 3931
8.581 cm

Measured from angle of locking lug to face of breech block. 0.001cm as I can best determine using digital micrometer. So, the variable seems to be broaching the LC location in the receiver, and receiver/barrel interface dimensions. Coupled w/ minor variations in chamber reaming, this may be why we can interchange bolts relatively easily in a rifle whose 'total' headspace (LS face to .400" dimension on chamber shoulder) is properly set. You can bet that bolts did not vary by more than a thousandth or two.