Hey guys, I have a bit of a conundrum.  I had a customer bring in a custom barreled Mauser action and wanted me to find out what the caliber is.  I have a chamber cast but I cant identify it as a recognizable caliber.

I figured someone around here would have an idea what it might be.

It seems to be a really long 6.5 Creedmore to be honest. Im wondering if the barrel was just chambered way too deep.

Case is roughly 2.25" long, bore is 0.260". Neck diameter is  0.290", shoulder is 0.470" and the base is close to 0.490".  The bolt face on the rifle is 0.473"

Bore appears to be about 1:8 twist.

I just wanted to make sure there wasnt something odd out there that was similar to Creedmore but longer.

Thanks!

If this was a sporter made in Germany look under the stock as they tended to mark the caliber there. Sounds like a 6.5x57MM Mauser.

Just a few 6.5s!...  L to R - Grendel, 6.5 x 47 Lapua, 6.5 CM, 260 Remington, 6.5 x 55, 6.5-284
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6.5x55 looks like a possibility. Thanks for the input guys!

6.5x55.

The Hornady loading book has the specs for several different 6.5 caliber cartridges.  I'm betting 6.5 X55 Swed.

If the action and barrel are older the assessment of being 6.5x55 Swede holds even more water as that caliber has been used in Europe for over a century, whereas we here in the US seem to have only jumped on it comparatively recently.