I know I have seen Parker research letters stating that a gun was sent back to Parker to have the chambers lengthened from 2 1/2" to 2 3/4". Is there any documentation showing how this was performed, or has anyone taken msurements or chamber castings?
Also guns such as my early Parker 28 has documentation showing it was ordered with 2 3/4" chambers. (It is on a 0 frame). So I know the OD. would be thicker than a 00 frame. Possibly the chamber length request drove he need for an 0 frame. Has anyone seen an original 28 with 2 3/4" chambers on an 00 frame? ( I'll see what I can find out on the Parker site)
LC Smith built some 12 gauge Long Range, and Waterfoul guns with 3" chambers, were different barrel blanks used? Some comparison measurements between the 2 3/4" and 3" Guns might be interesting.
Finally I remember taking measurements of the OD of a number of my 12 gauge guns a few years back at 2 3/4 and 3" and as I recall there was very little if any change in the measurements. Also the ID of the bores and chambers were all pretty consistent. At the time and even now I struggle understanding how moving the chamber forward 1/4" could be so critical to the integrity of the barrel. It just seems to me that the wall thickness of the chamber and bore would not have changed much in a 1/4", and if the same ammunition was used the pressure curve measurements would just move forward a quarter inch.
I'm not arguing my point just attempting to better understand the impact to the integrity of the barrel.