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

[tiriaq]

With respect to the head diameter of 6.5x55 and brass with .30-06 diameter...
I have formed 6.5x55 brass from .270 and other brass. Works - BUT - there is noticeable expansion in front of the solid head. Never had a problem, but if a case happened to fail, rather than fire form, there could be quite a release of gas.

 

[BLCB]

This is an odd situation, to say the least. The rifle itself not so much but the particulars in-between.

 

[woodchopper]

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.

This would be my conclusion

rifle in 6.5x55 had a 6.5-06 reamer run into it and now it can chamber either round the 6.5x55 body taper and .480" base diameter holds the round in place and the 6.5-06 headspaces on the shoulder and the case centers on the forward part of the chamber.

you could fire either round

but neither will really fit

the 6.5-06 will have the base above the web bulged out and the 6.5x55... well we have pictures.

to fix that...... I guess you could wildcat something like a 7mm RM with a 6.5mm neck, custom reamer. Or rebarrel it to something you want....

but I see the OP is sending it back for refund.

 

[Potashminer]

"wildcat something like 7mm RM with a 6.5 mm neck" - I think Winchester did so, in 1950's - is called the 264 Win Mag. Not sure a Swede ex-military rifle could stand up to that, but no doubt someone has found that out!

That is the trouble with today's cartridge line-up - it is VERY HARD (but not impossible) to "invent" something that has not been done already.

 

[woodchopper]

"wildcat something like 7mm RM with a 6.5 mm neck" - I think Winchester did so, in 1950's - is called the 264 Win Mag. Not sure a Swede ex-military rifle could stand up to that, but no doubt someone has found that out!

That is the trouble with today's cartridge line-up - it is VERY HARD (but not impossible) to "invent" something that has not been done already.

yup, if there is a practical reason for something to be developed it is likely that its been done.

I thought I was on to something a few years ago and then I found the specs to the 357 Herrett.....