Shotgun Forum banner

Low Pressure Loads

705 Views 3 Replies 2 Participants Last post by  JimfromTrafalgar
Logically, this should be posted under Reloading or General Interest but because of the interest shown in the Flues strings I am posting it here. Before WW1, shotgun pressures were held to 8000-8500 pounds of pressure- pretty much duplicating black powder loads. After the war, interest in repeaters blossomed and manufacturers increased pressures to the 13000-135000 pound level, causing blown Damascus barrels, cracked recievers and stocks. It also makes the oldies kick like a mule.

Low pressure load data are found in loading manuals and can easily be produced by anyone capable of reloading shotgun ammunition. It is commercially available from Galazine's, Cabala's or Poly- Wad. Give the old guns a break. In fact, give yourself a break. You'll be glad you did.

1 - 2 of 4 Posts
Amen. I beat that old horse continually. I use nothing but 2 1/2" Gamebore loads in my old Belgian 20ga. since having the hinge pin replaced. The gun and I are both better off. With published velocities of around 1200 fps, I don't feel I'm sacrificing range or knockdown power either. Cost is around $6.00 a box. I think most people differentiate black powder from nitro, but don't realize that design pressures for nitro changed as well. In going over some old info on proof pressures with a gunsmith/friend of mine, it appears that some modern loads may be approaching "proof" pressures. Yes, the gun will handle such pressures, but I don't think anyone would recommend continually re-prooving any gun.
Yes, the gun was originally chambered for 2 1/2" shells. At some point the chamber was lengthened to 2 3/4". When I got it, I started shooting standard game and target loads through it. After a few hundred rounds, I started noticing a slight amount of play. At that point I had the hinge pin replaced, which brought it back to like new condition. I'm not saying that those few hundred rounds alone caused the gun to loosen up. After all,it is 75yrs.+ old. That's when I started doing some research on the subject. With the benefit of the internet and a friend with an extensive technical library, I discovered just what the gun was probably designed at and what I had been putting it through. Along with data on what Belgian and British proof pressures probably were at the time, I used the old British game gun rule of thumb, a gun should weigh 96x the intended shot charge. In my case; a 5lb.2oz. gun, converted to total ounces is 82oz., divided by 96 = .854 oz., very close to 7/8 oz. In fact 7/8 x 96 = 672/8 or 84oz. If my digital scale is correct, my gun is 2oz. shy of the standard. After all the other digging through books, it turns out that the appropriate load is 7/8oz. in a 2 1/2" shell, which I could have arrived at using the original gun marks and the 96x rule. I don't know how well this works with most American made guns, as they seem to run a bit on the heavy side.
As far as patterning,I haven't properly done that yet. I will be soon as measurements indicate that it may be choked a little tight for grouse,[which was why I bought it], but I do hit well with it.
I hope that explanation wasn't too confusing, or long winded. :lol:
See less See more
1 - 2 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.