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........
Well Doug . . . good for you, and we should all shoot what we want to shoot. And, I should add, KNOW to be safe.
I just ran an interesting test. Went to my supply of factory 20ga shells, picked out a Gamebore "Traditional Game" load in a 2 1/2" case (so marked on the box; marked 65MM on the hull), as well as an Estate standard 2 3/4" shell. When fired, the Gamebore actually measures 2 9/16", and the Estate less than 1/16" more (under 2 5/8"). Since the information on the Gamebore box gives me the proof data for that shell (850 bars), and since it's a one ounce load, are you suggesting that if I reload the Estate, with 7/8 oz of shot, to a service pressure well below that acceptable in a standard CIP proof (850 bar) gun, that I'm doing something dangerous? In fact, it's almost certain that the pressure--and clearly the recoil, given that the Gamebore is a 1 ounce load--will be less in my reload than in the factory shell. And please note, the Gamebore is CIP-approved--which means that's not Brown talking, nor just the British Proof House talking, but ALL those countries that are part of the CIP. Which would be all of Europe.
Obviously, the European proof houses don't need to "hear from me". They've already approved shells longer than the length of the chamber for use in guns they've tested--per my recent experiment.
I don't happen to have either a German or a Belgian 2 1/2" gun handy at present, Doug. However, I have fired thousands of shells in British 12's and 16's, chambered 2 1/2", with factory cones, without damaging the standard American hulls I reloaded for those guns. Obviously, being an observant type, if I'd been blowing the ends off my shells, I would have stopped what I was doing.
As for the availability of 2.5" cases . . . in fact, as you know very well Doug, they are NOT available in the vast majority of places shells are sold in the US. 2 3/4" is our standard, and that's what our target ammo (our very best hulls) come in. Since I don't need to bother trimming those hulls, or buying 2.5" hulls, the question is not why shouldn't I do it, but rather . . . WHY SHOULD I DO IT?
And if you only shoot the "correct" ammunition in your guns . . . THEN HOW WOULD YOU KNOW THAT 2.5" HULLS LAST LONGER THAN 2.75" HULLS? Inquiring minds would like to know. Sounds to me like there's a contradiction somewhere in your "evidence".
As for the patterning thing, I have "evidence" in the form of an article from The American Rifleman in the 1930's, written by a man with long experience in the American gun industry (since the 1890's). Back then, some of the top trapshooters were in fact INTENTIONALLY shooting factory ammo longer than the chamber length in question. Why? Because, through testing, they had found that the longer shells in the shorter chambers gave BETTER patterns, not worse ones. That, of course, had to do with the paper cases opening into the cone, as mentioned earlier--which does not apply today. But why would patterns be worse due to the extra case length, if they weren't in the past? And how would you know, since you tell us you only shoot "correct" ammunition in the guns in question? I have patterned both British shells and my own 2 3/4" reloads in British 2 1/2" guns, and have gotten very good patterns from both. And I certainly have not observed that my patterns from 2 3/4" shells were inferior to those from the factory ammo.
And the tests to which Burrard and Thomas both referred . . . those were conducted with FACTORY AMMO, 2 3/4" shells especially loaded to be fired in guns with either 2 1/2" or 2 3/4" shells. Eley would not have made them and so marked them, had the proof house not approved of the practice.
As for the bozos shooting high power 2 3/4" shells in short-chambered guns . . . again, both Burrard and Thomas were quite clear about the danger of that practice. And stated--as I did in my previous post--that it's not the length of the shell that gets you into trouble (if it's only 1/4" longer or less--almost always less), but rather what the factory put in the shell to start with. Reloading standard American hulls to appropriately low pressures is a very different thing than running out and buying American 1 1/2 oz 12ga loads in 2 3/4" hulls and stuffing them in short-chambered guns. One would have to be a real bozo, for sure, to do that.
