doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com So, pressure is a function of payload?

With all the discussion you'd think I'd have it down.

Looking at 16ga offerings tonight, I assume that 1oz loads will be less pressure than 1-1/8oz loads?

Does it follow that a 4/5oz 16ga slug will be less than 1oz of 7-1/2's?

I noticed that Rem. no longer puts dram eqiv. on their boxes but now uses fps.

Well sorrtta... Powder burning rate, depth of crimp, buffer and what one, case selection, primer selection, and wad all enter into it too. To further comlicate understanding/comprehension, pressure absolutely does NOT enter into the equation to calculate recoil. The Hodgdon books/phamplets have lots of in depth explantion about these factors specifically in shotshell reloading. I think only a dude with a PhD. in physics can really "understand" it all. I just stay with below max loads, then chronograph 5-6 loads to see how well I stack up to the published data. Best, Dr. BILL

Niceties of bore size and volume aside, I don't think it's that complicated. Pressure is a function of how much gas-producing stuff you've got to burn, of how fast you burn it, and of how long the inertia of your plug or piston (the shot charge) can contain or restrict expansion of the gas.

jack

So the heavier the plug, the longer it takes to get it moving, higher pressure

Without wishing to sound 'smart', stick to published data that shows pressure levels suitable to your gun and don't worry about anything beyond the accuracy factor with slugs or the patterns with shot, but DO follow the whole recipe listed. Asumptions can get you into trouble quickly .. well, some anyway. That's why you want to go w/published data. Still, even there a misprint is always possible, so compare with other data and if it seems out of sync then consider it suspect and look elsewhere. Just some thots.

You can pick the single causal relationship that appears to justify what you want to do if wanting to do some particular thing while reloading is what this is about. I'm sure there are anomalies and the thing ain't linear; maybe a lighter payload requires a faster powder or more or a slower one than does a heavier payload. Oh hell, what tw says.

jack

From an alliant handloaders guide & using the same hull & primer I find a load which pushes"
1 3/8 oz of shot to 1200 fps @ 8,100 psi & a load which pushes;
1 1/8 oz of shot to 1200 fps @ 9,300 psi
But to answer your question, yes the pressure is higher for the 1 3/8 oz load IE the total average pressure is higher. The heavier load is with Blue Dot while the lighter one is with Red Dot. The Red dot load peaks higher, but also falls off faster so the total area under the curve would be less. Thus yor statement that for a heavier pay load the pressure is higher is true, as long as you understand this has no reference at all to the actual "Max" peak, but the total average pressure. Does this make sense??

The last one looks right.

I don't reload, I just want to take it easy on some of my older guns. I'm a firm adherent to the school that feels anything can be killed with the proper non magnum rifle cartridge and try to expand that to my shotgunning.

I want to shoot loads that will be easy on the likes of 80 year old Ithacas, Nitros, Parkers, etc.

I saw that Remington offered 1oz & 1-1/8oz 16 ga gane loads and was hoping for a simple rule of thumb, the 1oz load would be less punishing.

I'm learning it's not as simple as that. Even if we knew chamber pressures, it doesn't necessarily correlate to recoil which beats up the wood on old guns.

I see that RST has light loads that only seem to be reduced payload, 7/8oz 16 ga shells.

Rob

I'd probably go with this load, are they 2 1/2 inch? I can't tell you what the chamber pressure is, but I'd bet either one of those Rem. Factory loads is fairly hot. Same for factory Federal, Winchester etc. Generally speaking, higher pressure shotshell loads tend to be more consistant, are more likely to go bang in cold weather, and reliably cycle the few gas autoloaders that are out there (in 16g). Obvoiusly, this is important for a manufacturer, but may not be ideal for an older double. 2 1/2 inch factory loads would likely be loaded to a lower pressure than 2 3/4 inch.