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Many mfgr's list FPS info on the box - is there a way to judge the relative pressure hese loads are generating?

I assume a 1400 fps load generated larger pressures in the bore than a 1200 fps load - shot size/load benig equal...

If I intend to feed factory loads through the new to me vintage bore, I'd like to make intellegent choices when selecting loads.

If there are existing links discussing this topic, please point me in the right direction.

Thanks

Member Joined: 27 Jun 2005 Posts: 1545 Location: Michigan

First off, what kind of Vintage gun are you talking about.
A shells FPS is no indication of it's PSI. Just like the high brass, low brass, on a hull is no indication. If your looking for a load within a certain PSI range. You'll have to do your home work to know what loads your shooting.
A little more information on just what your looking for would be helpful.

vintage = 1950 & earlier - or maybe just pre-war

as for PSI range - I have no clue WRT numbers. I was wondering if there is a realtionship to FPS & PSI to use as a guide.

If its a domestic gun made after 1930, it will handle any 16 ga. 2-3/4 inch factory load, regardless of velocity. However, if its hinge gun and is even a bit off face, get it fixed before shooting it. The slop in the tolerences will allow it to peen itself continually looser. If its a repeater with the proper headspace, then shoot away without worry.

There is no way to correlate velocity and pressure. However, most modrn 2-3/4 inch domestic loads operate above 9000 psi to insure they will function in an autoloader.

There is NO correlation between FPS and PSI, just as there is also NO correlation between LUP and PSI.

Joined: 15 Dec 2005 Posts: 287 Location: missouri

As was stated there is no correlation between the velocity of a shotgun shell and it's pressure rating. Different components (hulls, wads ,etc), primers and powders will make dramatic differences in pressures generated by a given load.
Using a 16 ga 1 1/8 oz hunting load in the Federal hull for example...using the exact same components (1 1/8 oz shot, SP16 wad, Fed 209 primer) but using Herco in one load and Blue Dot in another. Both loads have a listed velocity of 1295 fps however the load using Herco produces 10,300 psi listed while the Blue Dot load produces 8,600 psi. Both loads also fall within SAAMI specs for the 16 ga.
With factory loads you usually never know what components are used, and they are assumed safe as long as they fall within SAAMI specs for the given gauge shotgun. The velocity rating given to factory loads can be based on components that produce anywhere up to 11,000 psi for the 16 ga. again within SAAMI specs.
The only way you can really be sure is to load your own and use very low pressure recipes to start with.