Could anybody give a brief 101 on headspacing as it relates to rifles chambered for modern rimless cartridges??? In particular, I am interested in what could cause a rifle to develop a headspace problem and what the potential consequences might be...

I am asking this in relation to a friends 6.5x55 which literally "exploded" when he took a shot recently. The wooden stock and plastic magazine and magazine well were destroyed, one of the lugs on the bolt sheared although the bolt remained jammed in the action. The chamber and throat had a slight "bulge" although this only became apparent when a when a smith took some measurements.

Somebody has suggested the rifle could have had a head space problem, but i did not think this could have caused such a failure.

The remaining ammo in the batch he was using was pulled and checked and found to be all ok. The guy only reloads for this calibre and and only had one set of components available.

Thanks in advance,

Pete

headspace for bottleneck rimless non belted cartridges is froma datum on the shoulder angle to the boltface. If it became excessive, it would happen over time usually and case seperation would occur and increase with the increase in head space. I am not a forensic firearms expert, but it seems unlikely that head space would be the problem of such a catastrophic mishap like you describe..a weak action, high pressure loads, over charging, or a combination of them....tons os question to the actual owner and examination of the gun is the only way to TRY to find out....bob

Pete E---

That would be an atypical reaction to excess headspace.

A bulge in the chamber/throat area is almost surely the result of grease, wax, or ice in the bore.

It would take the sectioning of the barrel and close metallurgical inspection to say for sure.

Gentleman,

Thanks for that...the various parts of the rifle are on the way back to the factory as we speak, and we are both hoping they can shed more light on what has happened.

Regards,

Pete

Pete E---

You say it's on the way back to the factory?? Which factory?

I know you're in the UK and maybe you can get some answers over there......here you won't. Not from a factory, anyway.

I'm just curious.

What powder does he use? An article exploring
other 6.5 incidents, show that in cases with
this shape, and some powder types that are not
at high load density, will ignite incompletely
at the start, the bullets moves into rifling
and stops for a few m-sec. then powder takes off
and it is like detonation as bullet acts like
obstruction.In a Handloader or Rifle article a few years ago.Ed.