Excess headspace...and then there's this!

While it could be, the case head on the 6.5 is significantly different than the 06.
Did some research, the case head on the 6.5 x 55 is aproximately 1/100 inch bigger than the '06. The 6.5 A-Square (6.5 - 06) is about .3" longer.

No commertial ammo available; A-Square is defunct. The bolt would work, but be a tad sloppy with the 06 case.
 
actually the headspace is fine no case separation or backed out primer
I had read that some combinations "lodge" on the body tapers - I read that 7.62 NATO lodges in a 30-06 chamber - headspace is totally irrelevant in that case - the case is "held" for the firing pin to strike that primer and set off the charge - some have said that the external extractor on various rifles (like Mauser 98) can do the same thing - hold the cartridge enough for the firing pin to strike the primer and set it off. Versus examples like 280 Rem - it will NOT chamber into a 30-06 chamber because the "headspace" dimension is different, but some will run a 30-06 case into a 280 Rem die and claim that to be their 280 Rem. In the past, I had a notion to re-chamber a 7x57 into 280 Rem - except 280 Rem chamber reamer will NOT clean up the very rear of the 7x57 chamber - even though the barrels (bores) can be the same internal size. I suspect that is what the OP has - someone has reamed an original 6.5x55 rifle to accept a larger 6.5 cartridge, and has NOT re-marked that barrel with the "new" chambering. Chances are good that bolt face is still properly sized for 6.5x55 which is a bit larger than 30-06, but likely "works".
 
To clarify my last post - based on some emails that I received about it - yes, the bore would have to also be reamed out and re-rifled if that was to take a 30-06 round - however, OP stated it was "definitely" a 6.5 mm bore - so NOT reamed out - however, a "wildcat" chamber can/was easily made by necking down 30-06 cases - (plentiful and cheap) to accept 6.5 mm bullets - that then required a chamber reamer to elongate the chamber - no doubt variations existed about whether the result was neck turned or not - could stay with "thick neck" or go with "thin neck" when chamber reamer was ground. Then submitted to SAAMI, which would likely have played with headspace dimensions to ensure the result would NOT UNSAFELY fire in another cartridge's chamber - I think A-Square may have submitted the previous "wildcat" 6.5-06 to SAAMI for approval.
 
Back
Top Bottom