Chamber / Case length ?

[mgsontour]

Hi, I wonder if you can clear this up for me please. . . . the attached pic shows the details of my bismuth cartridges. . .  why is the chamber length shorter than the case length? Thanks in advance for your help

 

[wymberley]

Standard chamber lengths go in multiples of either 1.4" or c5mm. The next step up from the 65mm (2&1/2") is 70mm (2&3/4"). As seen the 67.5mm is smack bang in the middle and it is deemed acceptable for this length cartridge to be used in the smaller chamber. I personally would think twice about it should you have an old English 2&1/2" chambered gun - there's proper 2&1/2 (65mm) cartridges to be had.

Edited February 6, 2019 by wymberley

[mgsontour]

Thanks for your advice wymberley, I'll speak to the gunsmith who sold me these reasonably priced cartridges OR might even try a new gunsmith!

[Guest cookoff013]

67mm is recognised as a 65mm chamber.

the minimum specifications for a 65mm chamber are 67mm.. if you look at the specifics of chamber length its +2mm minimum.

so say you want to manufacture a chamber / barrel and have it cip stamped. to be able to have a 70mm chamber the manufactured chamber would need to be 70mm +2mm (minimum)

to get labelled as 70mm, and then have to be proof pressure tested for it.

you can check the cip to which europe adopts the firearm pressure / proofing standards.

if you have any more concern, aka that your gun is very old and you still doubt the chamber size, you can get it measured, to see what the actual chamber size is.