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

Rob, if I understand anything or anyone at all, it's that there is a reasonably clean, uncluttered correlation of recoil of the gun to weight and velocity of the ejecta; i.e., shot charge or solid plus wad and powder residue a la old Sir Isaac. Less going slower in one direction means a whole lot more going mega slower in the other. 7/8 oz in the 16 is a reduced payload; increasing its velocity will eventually make it comparable in recoil to 1 oz. load going somewhat slower. Sort of like little M x big V produces the same recoil result as does big M x little V. No correlation to pressure, peak or average. Ok, I am challenged by the formulaic!


jack

RR - per your hypothesis, NO, absolutely not!!! There is no prima facia correlation of shot charge/slug weight and peak pressure. Your gun's action and barrels are interested in peak pressure. The elcheapo shells are intended to cycle semi-autos and do not take older doubles into consideration. If you are going to feed older doubles, you are going to have to use shells that are KNOWN to produce lower peak pressure. This generally means "specialty" shells or purpose made reloads (ones with low pressure).

The wood part of your guns are intersted in recoil force. You can safely estimate recoil force as a function of shot charge weight and velocity per above.

The care and feeding of older guns requires low pressure, light recoil, and good lube kept clean.

Rob, to answer your question concerning typical American factory loads . . . the 1 oz 16ga load has a published velocity of 1165 fps. The 1 1/8 oz loads are mostly 1295 fps. So the latter is not only heavier but also faster, which means a significant difference in recoil, which is also a factor where old guns are concerned (especially on old stock wood). American ammo makers don't list pressure, but that's probably higher too on the heavier load.

Found some Federal 7/8 oz factory 16's the other day, figured "Hot damn, they're finally doing something for those of us looking for light 16ga factory loads!" Then I saw that the box says 1400 fps. Without doing the math, I'm pretty sure the 1 ozers at 1165 fps have less recoil.

Rob,

You are asking the right questions.

The problem is with the ammunition makers. They think the entire market is driven by muzzle velocity. So as the payload changes, they tinker with the powder, charge weights, etc to get the mv to hit the magic 1200fps. You are correct, you will not find many listing pressures, but again they are quick to print the velocity on the box.

As Rocketman pointed out, they have to produce a shell that will cycle those semi-autos. That is where the dollars are being spent.

Pete

Rob: this thread lists pressures for a number of 16g loads. Several manufacturers declined to reveal pressures including Winchester, ARMUSA, and Eley. Hope this helps.
http://www.16ga.com/forum/viewtopic.php?t=2410
BTW: The Federal and Winchester 1 oz. 'Game Loads' are 1165 fps but the Remington is 1200.

Recoil as has been pointed out so many times here (But hard to get by all the "Snake Oil" salesman pushin "Felt Recoil") is a function of weight times velocity, & is totally unrelated to "Peak" pressure. To make it easier on the wood you either cut the payload, cut it's muzzle velocity, OR BOTH. Peak pressure is of concern primarily to the bbls but can also have an affect on frame strength. Has virtually no affect on the wood, or you.

If you want to protect your older guns consider this, pressure is not the only factor. Reducing recoil is good to help protect old wood and reduce the impact on parts like the joint.

That being said, all other things being equal (same powder, velocity etc) less lead means less recoil, less wear and tear.

and

That being said, all other things being equal (same amount of lead etc) less velocity means less recoil, less wear and tear.

So, use the lightest load in lead and velocity that reliably gets the job done. You may be surprised at what you can do with 7/8 oz of lead at 1125 fps.

Jeff

For standard factory loads there is no corrolation between payload, velocity, and pressure. If you are a factory you will use faster powder behind a lighter payload at the same velocity resulting in roughly the same peak pressure range. The point being that with the faster powder you will use half a grain less. Multiply half a grain by a million cartridges and you are talking money.

The title of this thread: "So, pressure is a function of payload" kept reminding me of the story of the dude who showed up in the Antlers Bar, the night before big game opener. He was all dressed up in his brand new camo outfit and trying real hard to be one of the guys. After he bought the house a round and they were about half consumed, he asks "So, how old does a deer have to be before it's considered an elk?"
Sorry, I just couldn't help myself!

The Fiochhi GT's are a surprise, I knew about the RST's, good list to have, thanks Revdoc.

Maybe we could get the NRA to lobby for manufacturers to list this info? Worth sending an email? Do they actually listen to members?