doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Help needed on pressures of modern loads?

A while back I paid a few bucks to the 16ga reloading group for their spreadsheet of load data. When I did so I agreed not to publish the data, so I won't post it here--if anyone wants it, I suggest emailing russel Gray and joining up--it's well worth the money. Also keep in mind I'm no expert, I'm merely regurgitating my interpretation of the data I've seen...so buyer beware.
Among other gems the main spreadsheet contained actual pressure and velocity test data as tested by Tom Armbrust, for a variety of 16ga factory ammo. I have not looked over the actual test reports so I'm assuming things like temperature varied enough over different test runs that the data should not be used more than in a general sense, but I do know that the data represents average figures for 3-5 shots of each load--not 100% scientific, but the best source of info on this I've seen. Keeping in mind that this was for 16ga ammo only, some generalizations might be made: 1) a larger shot payload did not automatically equate to higher pressure, although there seems to be some correlation. 2) 2 1/2 inch shells do not equate to lower chamber pressure. 3) american shell companies seem to make shells that will cycle autoloaders, and their pressures tended to be on the higher end of things--usually. The tested ammo from rem/win/federal hovered around 10000 psi +/- 1000psi. European ammo companies had more variety, going as low as 7500 and as high as 12000+ (over the SAAMI max). 4) Even some of the ammo marketed specifically for older guns had pressures in the 10,000 to 10,500 psi range, although most hovered around 8000 psi.

To compound my confusion, when I spoke with a noted shotgun barrel smith a while back he discouraged me from worrying too much about pressure, and said that at least with fluid steel guns "in good working order" (to be defined by someone a lot more qualified than me!) it would be more worthwhile to worry about recoil to protect the old wood.

Seems to me that if this is something to worry about that the only way to ensure that you are shooting something of a known entity pressure and velocity-wise, is to either contact the ammo company and see if they'll give you pressure and velocity data (they won't all do this), send out some shells to be independantly tested, or roll your own from tested reloading data.