Parker and 2 3/4" chambers
 

When did Parker go to 2 3/4" chambers in 12 ga? I don't have a means of measuring chamber depth on my old gun.

They have always made chambers to order. As far as a company policy of "2 3/4" chambers in 12 gauge guns", I haven't seen anything in their advertising or catalogs to indicate a break point.

I just dropped my Superposed open. It's a 3". I peeked down there and saw what looks like an obvious step about three inches down the chamber. I figured ah ha! I'll just measure the chamber length with a metal tape measure. I slid the tape down there thinking it'd land or stop when it hit that step. Didn't do it. It just slid on by. I didn't feel a thing. Am I breathing too much ozone? What gives?

How do you measure the chamber length anyway?

Measure to the start of the forcing cone I think.

The cone shadow can look like a "step", or dirt. Use a blade chamber guage speced to your gun; or, better, a dial type chamber/bore guage.

What looks like a step is actially a taper called the forcing cone.
It is tricky to measure without a tool to do so. You can put a pencil or a dowel into it until it is at the taper and measure the depth.
Or if you have a gunsmith you work with just bring it to him and have him drop his gauge into it.

I've did what Brain said before you can figure it out with that method.

A method used by some is the credit card method. Cut a credit card lengthwise until it's just a friction fit in the chamber mouth. Push it in until it hits the beginning of the forcing cone, mark the card. Most chambers are slightly tapered, so the card will get tighter as it goes in, but will stop at the forcing cone.

Think I'll use a gunsmith to measure chambers. I've got too good ones here. I'm pretty serious about this chamber length question since my GH, that I'm picking up Monday will likely sport a shorter chamber. Did they make 2 3/4 chambers in those early (1895) GH grade guns? Can I assume it is short?

If it is, should I just shoot 2.5 inch shells or have the chamberes reemed to 2 3/4? Frankly, being new to damascus tubes, I don't know how much flexibility I have. No matter how much I read that they are strong enough, I have to admit being leary. Moreover I am not opposed to shooting shorter shells. I'll never shoot standard store bought shells in my GH. I'll shoot RST/Polywad and/or load my own.