Gas gun head spacing

[Sako man]

I am wondering if head spacing a gas gun barrel and bolt has any real effect in accuracy. Bolts and tolerances on gas guns in their nature are very loose, so it would appear. So question is, am I mistaken in my assumption, and does it actually make a real difference in accuracy, is it worth the extra cost of a gas gun barrel with matching bolt?

Thanks

 

[roostercogburn98]

Is a good place to use tolerance stacking in your favor IMO. Take some really quality parts and have them fitted as close as functionally possible. Would take loads of slop from the inherently sloppy design. Less movement in any direction, should theoretically translate into better accuracy.

Maybe I’m crazy?

 

[JBoomhauer]

Headspace isn’t really about accuracy. I can have an accurate load right up to case head separation.

 

[nn8734]

I am wondering if head spacing a gas gun barrel and bolt has any real effect in accuracy. Bolts and tolerances on gas guns in their nature are very loose, so it would appear. So question is, am I mistaken in my assumption, and does it actually make a real difference in accuracy, is it worth the extra cost of a gas gun barrel with matching bolt?

Thanks

it makes no difference for precision. The only benefit (maybe) that comes with getting a “headspaced” bolt with a new barrel is knowing the chamber head space falls somewhere within sammi spec (ex: .308 win is 1.630-1.634, 7.62 nato is 1.635-1.640).

I’d still confirm w/headspace gauges or a go/no go/field gauge.

 

[roostercogburn98]

Headspace isn’t really about accuracy. I can have an accurate load right up to case head separation.

Not necessarily fitting for headspace only, but for between the barrel/bolt locking lugs. Tighter fit, less movement while firing before the unlocking begins in the cylce. Also would lead to better lug engagement, which should lead to more solid repeatable SD/ES which could help with MV discrepancies and vertical stringing. Once again, maybe I’m crazy.

 

[Rocketvapor]

Matching a bolt to barrel (a sales pitch item) sets head space to a nominal bolt (or one you supply).
Lug length and bolt face depth do have a tolerance but can be checked separate from barrel/extension.
Bolts with out of tolerance dimensions (or edge of tolerance) should be sorted out, returned if possible.
A tighter fit can interfere with a bolt with less depth/longer lugs.
Measuring your own bolts can find those with the potential for long or short headspace.
A barrel maker needs to know bolt dimensions and desired headspace to fit an extension.

What do you do when you replace a bolt that was matched to a barrel?

 

[r.tenorio671]

I am wondering if head spacing a gas gun barrel and bolt has any real effect in accuracy. Bolts and tolerances on gas guns in their nature are very loose, so it would appear. So question is, am I mistaken in my assumption, and does it actually make a real difference in accuracy, is it worth the extra cost of a gas gun barrel with matching bolt?

Thanks

.....it is more a safety factor.

Some things to consider by the prospective buyer:
- cost, the "matched bolt" option is comparable to purchasing one separately (bolt individually or complete BCG)
- warranty, ensures any bolt related issues are covered for both bolt & barrel.
- availability, no waiting or searching for a bolt if supply channel is challenged.
- accuracy, potentially "improved" due to being in spec and removes one of the myriad of factors that influence accuracy.

It appears that some folks put emphasis on the "bling-bling" factor of the BCG and opt for a complete BCG as opposed to a "matched" bolt. In theory, the matched bolt from the barrel vendor can be used with the "bling-bling" BCG by a simple swap assuming both are "in spec".

Buyers not intending to build multiple platforms/uppers or swap barrels are best served by going with the "matched" bolt. Buyers that do build multiple platforms/uppers or swap barrels can save on the cost of headspace gauges, if so desired. HS gauge purchase is a "one time" investment for the builder/assembler, but is only a "check" for bolt or barrels compliance to SAAMI specs.