[gordy h]

What is the max.safe PSI for a single barrel? I see in the books PSI anywhere from 9000 to 11000.

 

[GW22]

That's in hundreds of pounds, not thousands.

-Gary

 

[timb99]

In other words, 11,500 psi for everything except the 3-1/2"

 

[Shooting Coach]

Don't forget, the ammo makers are using new brass. We are not. I hesitate to go over 10,000 PSI, prefer over 9,000 PSI for clean burn in all weather.

Hard to get that minimum pressure with the 3/4 oz Sporting loads I have been shooting.

I will try to get some of these shot on the 16 yd line this weekend, work and weather allowing.

 

[timb99]

Not sure what the brass has to do with it. The pressure boundary is the barrel/chamber, not the brass on the shell.

 

[mike campbell]

The "max psi" we're speaking of is not a red line. It is not the absolute maximum pressure a shotgun can withstand. It is the recommended "maximum average service pressure"....meaning a modern 12ga in good condition is intended/expected to digest 11,500 psi loads day, in-day out, every day, year in, year-out, every year for tens of thousands of rounds. The gun will eventually wear out, but it won't fail catastrophically from SAAMI-max loads. That's the reason it's not difficult to find published data for loads averaging 11,000 psi.

 

[mike campbell]

I never hesitate to withhold information from people if I've reason to suspect they could benefit from it. I think it's best that people be educated. I certainly appreciate it when others point out that I might be laboring under a misconception and help me to understand why limits and boundaries exist. I find that, when we understand the reasoning behind "rules," we're more willing and likely to play the rules.

I don't advise anyone to assemble any load for which pressure data does not exist. And if they wish to hold themselves to some arbitrary pressure level below 11,500 psi, that's perfectly fine, too. OTOH, I'll occasionally suggest there's no reason to shy away from loads with published pressures in the 11,000-11,500 psi range.

That said, I don't wish to discuss the meaning of the values in the two columns to the right of the MAP column.