I’d would really appreciate some advice. I have an old shotgun, on which I get differing opinions on whether it is safe to shoot. My father in law has shot it for years with no problems.
Question is, if I do shoot it later, is it safer to use normal 1oz 2-3/4″ loads? Is the pressure / recoil lower in a 24gm load than a gee whiz 34gm load?
I really don’t do old guns. If you have doubts as to the safety of a particular gun, take it to a gunsmith and get his opinion. This isn’t the kind of judgment you can make over the internet.
As to the pressures in various shells, that depends on a particular shell. You can’t always equate pressure to payload. The little .410 operates at higher pressures than most 12 gauge loads. Loads with large amounts of shot tend to use slower powders which broaden the pressure curve without excessively raising the pressure. Your operating pressure just lasts longer to push the big load out the muzzle.
Standard 12 gauge lead shot loads have a maximum working pressure of something around 11,000 PSI according to the latest manuals. This is true whether the payload is 1-1/2 ounces or 7/8 oz because it is the gun and the SAAMI (in the USA) governing standards which determine maximum safe pressure, not the shell.
Pressure has nothing to do with recoil. Low pressure shells don’t kick any more or less than high pressure ones. Calculated recoil takes into account only the weight of the ejecta (shot, wad and powder), the speed of the ejecta and the weight of the gun. Nothing more. Pressure is not part of the equation.
Some people feel that low pressure loads or loads with slower burning powders should produce more of a “push” than a “poke” and that this makes them seem as though they kick less. I doubt this very much as the slowest burning suitable shotgun powder is only a few micro seconds slower than the fastest. I doubt if the human body can sense the difference. I arrived at this conclusion after conducting several blind tests with a number of shooters. No one could consistently spot any difference in recoil between slow and fast powders which generated the same shot load speed.
Low pressure loads often kick less because low pressures are usually associated with low velocity loads. It’s the payload velocity that’s the key here, not the pressure.
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)