Pressure vs Recoil

[Paul Harm]

Many of you do know, but for those of you who don't, here goes. From the Accurate Reloaders Guide 2005 some info. The formula for recoil: mass of bullet or shot + wad + powder x velocity = recoil. Pressure is NOT mentioned in the formula. So don't think for a second that because a load doesn't kick it is a low pressue load. A couple of examples:
7/8oz 1200fps - Clays powder - 8900psi
7/8oz 1200fps - IMR7625 - 4400psi
1 oz 1200fps Clays 10,100psi
1oz 1200fps Solo 1250 6400psi
1 1/8 1200fps Clays 12,000psi
1 1/8 12oopsi Solo1250 6600psi
Those were the highs and lows that I found in the guides I had. Now I'm not worried about blowing one of my guns up by shooting factory loads, but I wouldn't want to shoot a nice SxS loose, so I shoot " low pressure" loads.
I have blown-up a gun, but that was my fault - wrong powder. Now for black powder loads. They kick more because there's more powder, hence more weight in the above formula - not more pressure. A 3 dram load by volume is 82grs [ about 75grs weight with my measures ]. If a modern shotgun reload is around 20 grs of powder, then the BP load weighs 55grs more: or about the same as going from a 1 1/8oz to a 1 1/4oz load. Now that's gonna kick more. From the Lyman BP Guide a 3 dram 1 1/8oz load is 5000LUP, or about 5500 to 6000psi. A 3 3/4dram load is 5900LUp, or 64-6900psi. That's still a low pressure load that kicks pretty good.
One more thing - I don't believe you can say what's a safe load by shot column height with todays modern powders. One would normally think a 1oz load is a light 12ga load with not much pressure. But as you can see from the above example it can exceed 10,000psi, and a 1 1/8oz can go 12000psi.
I guess I'm trying to say, and clear up is that there can be high pressure with out much recoil, and like with BP there can be a lot of recoil and low pressure. And the height of the shot charge does not dictate pressure. I approve this message - Paul

[Bruce Day]

Speed makes a big difference. I've been loading 1oz Clays at 1125fps with Win 209's and get about 5500 to 6000 psi per the Hodgdon manual. What's the difference at 40yards between 1125 and 1200fps? Maybe 6 inches. Those are my 12ga target loads.

On the other hand, I'll go buy a case of Fed 1 1/8oz 6's every few years for hunting season. Its still below the Parker service load highs. We have a 3 to 4 bird pheasant limit out here. What do you shoot in a day of hunting? Maybe 5 to 6 shots. Last case I bought cost me about $65 with tax.

[Blind Dog]

Here's a WAG from someone without Physics credentials beyond 101. Higher chamber pressure with load (ejecta), guage and velocity being equal should result in faster (quicker) acceleration and sharper reaction to the action. Is this what we mean by "felt recoil"? There are certainly many other factors, ie.; physiology/psycology of the shooter, his technique and the geometry and mass of the shootin' iron.

[Big D]

If everything else is equal - payload, velocity, ejecta, gun weight, the slower burning powder will result in lower felt recoil, because the reaction against your shoulder will be more of a push rather than a stab. Newton was right, however, the total recoil of both loads will be the same. Same reason why gas-operated automatics feel as tho there is less recoil - the pulse is spread over a longer period of time.

[Mike Stahle]

I just find it so hard to believe my Grandpa and many other grandpa’s lived much past 35 years old, shooting these out of their Dad’s old Damascus barreled shotguns.

[10ga Hammer]

He may have lived past 35, but did you ever wonder where all his teeth went?
Them suckers will at least loosen every filling in your head !!

[Big D]

I miss using paper shells in the duck blind. When I was a youngster, my dad would cut down a spent shell, creating 6 pedals. He would stand it on the brass base, and light it. It would burn with a small blue flame for about 5 minutes - just enough to warm this teenager's cold fingers

[Mike Stahle]

Originally Posted by John Dallas

I miss using paper shells in the duck blind. When I was a youngster, my dad would cut down a spent shell, creating 6 pedals. He would stand it on the brass base, and light it. It would burn with a small blue flame for about 5 minutes - just enough to warm this teenager's cold fingers

Very cool memory to have of you and your Dad.