Yes Larry, you are exactly correct. I am trying to keep it as simple as possible and as you pointed out the bottom line is what is “service pressure” and what that means for safe pressure loads to shoot. 10,733.79 is the service pressure but most UK ammo I’ve seen is far under that pressure. They just don’t seem to have the mania for hot loads we have. Why I don’t think they even think every hunting load ought to be going 1450fps, that seems to be the norm today. I am sure far more birds have been killed with loads below Service Pressure than above for the simple reason most loads always fell under it until modern powders started generating our current much higher pressures.
All we need is a simple rule of thumb type guidelines. If proofed at 850 bars keep pressure below 10,700psi. Or just under 10,000 for round numbers. To be kind to your stock aim for 7-8000psi, 1150-1200 fps. With 1 to 1 1/8 ounce shot. Since the stock suffers from recoil, not chamber pressure, and recoil is directly related to force, (velocity & payload), keeping both down reduces stress on wood. But “safe” is safe for the barrels, the rest is about wood health.
It would be nice if the UK did not have about half a dozen ways of saying the same basic thing and three, now four levels of proof information. But we are talking about a period of 150 years and things have changed a lot. black to nitro, Drams to tons to bars, chambers thrown into the mix with shot charge for good measure and now Superior Steel proof. Can’t see why anyone would get confused.
Jon, sometimes I think that our cousins across the Pond do it just to confuse us! The shotshell box is yet another example. They don't express velocity the way we do. Ours is quite consistent: it's measured at 3 feet from the muzzle. Theirs may be either a)"True" velocity, measured at the muzzle; or b)"Observed" velocity, which is the average over 20 yards; or, most recently, c)"Mean"velocity, taken at 2.5 meters from the muzzle. True velocity would lead Americans to believe that British shotshells are faster than American shells. Observed velocity, which is 1070 fps for a "standard" load, would lead us to believe that their shells are a good bit slower than ours. I'm guessing the Lyalvale shotshell box above carries a true velocity reading. The observed velocity standard for a high velocity load is 1120 fps. That equates to an American load with a listed velocity of 1235 fps. 1400 fps must be a reading taken at the muzzle.
