measuring shotgun chamber length?

[takem]

I have an old stevens chickopee falls side by side 12 gauge in great shape. Solid as a rock. It's marked proof tested 2 3/4". I've heard and read that old paper shells were crimped different and should measure the chamber it to be sure. I read so much online I'm confused.

Only thing I could think of was to put a 3 1/2" shell in just to measure. Measured exactly 2 3/4". so a fired 2 3/4 shell is 2 3/4" and that's what I've measured so I should be good with some low pressure ammo, correct? Am I missing anything. If it was 2 1/2 or 2 5/8" it would of measured that, right?
Thanks, Brad

 

[Virginian]

If it's marked for 2-3/4" loads, its good for all 2-3/4" shells. That gun isn't that old and has good alloy steel barrels. The pressure limit has been the same for ages.

 

[RugerMcMarlin]

ZZZZ

 

[waidmann]

Perhaps if you measure an unfired 2 3/4" shell it will make it more apparent. The shift from 2 1/2", 2 9/16" or 65mm to 2 3/4" or 70mm tracks with the change from roll crimp (over a card) to the familiar star folded crimp. If the gun is marked, trust the inscription. If it isn't assume the shorter chambers. Several U.S. companies continued with short chambers between-the-wars.