Larry:
I personally shoot 2.5" hulls which I buy or trim to size when new, 12,16 and 20......the 67.5 mm are available primarily in other parts of the world as are 65 mm, I don't buy European ammo for the doubles......I also don't run around measuring hulls either, because I know what works......what I do observe is the condition of any hulls in a particular gun after firing........
If the European proof houses stipulate that 67.5 is o.k. in 65 mm chambers, then you must speak to them with your hull measuring scenario, I am sure they would love to hear from you......
Being the 'technical' type you appear to be Larry, I am sure you are aware of the fact that most German & Belgium 2.5" doubles have sharp cones and will clip and damage the end, (or separate in two pieces) if 2.75 shells are fired in those guns, or maybe you only shoot other guns or are not familiar with that scenario, or maybe you grind out all your short cones....?....
Why is there so much resistance against shooting the 'correct' ammunition in any gun.....?.......Because some writer in the UK said it's o.k., is that the reason....?........Is it because you are cheap-frugal (you mentioned cost) and don't want to buy 2.5", or load 2.5"....?....Are 2.5" cases too much trouble, even though they are available most everywhere.....?......
As mentioned earlier, I have found that the 2.5" hulls pattern, shoot and last longer when fired in the "vintage" un-butchered 2.75" chambered guns as well.........probably because those chambers were machined and coned to fit the ammunition of the day, which was primarily 2 5/8 and 2 1/2 paper.......common sense one would think............
Since you like to measure---measure an old as fired 2 3/4" paper 'rolled' hull pre 1925, ..........then measure a modern star crimped 2 3/4 hull and compare overall length........
Since the SAME LOAD fits in both size cases-hulls for our vintage guns, what advantage is there to using a 2.75" in a 2.5" gun....Please explain what advantage there is.......availability, which we've already covered.......tell me, what is it.....?.....Don't reload....?.....Too lazy to put a short kit on the reloading press.....?.....Maybe just personal preference......?...........I would guess that is the reason.........?.....None of the other justifications make any sense whatsoever.............?.......Never have, never will......Have any of you people ever shot and patterned 2.5" hand loads.....for comparison....probably not.....?....
No two double guns, even from the same manufacturer will shoot the same pattern or have the same pressure peaks.......this is why the proof houses will not condone shooting 2 3/4 shells in 2 1/2 inch guns..........the other reason is that some bozo will eventually buy some high power 2 3/4 shells off the shelf and stuff them in there....with obvious consequences.................
I like what Salopian said in September of '06 when the same subject was extensively discussed......"play with fire and you will get burned"...."Did your momma advise you to stay back from the river before you fall in"............Or HoJo's from the same '06 thread: "I believe in using the shells that fit the gun"....and many, many more...........
I think everyone should shoot what they want........
