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I have been told for years the peak pressure with smokless powder in a shotgun is reached about 14" ahead of the standing breach. Does anyone have information to refute this?
Jim

Dave K

I quit visiting that website because of the fellow you mentioned. I agree, he is a keyboard cowboy with a little knowledge that gets expanded into "his brilliance". I would not take anything he says with a grain of salt.

I saw this same thing happen on a Diana Grade Superposed 12 ga. The bottom barrel simply split lengthwise under the forend. As memory serves me, this was an older model. The barrels were thin but had not been honed. I do not even load high pressure loads in my modern guns let alone the old ones.

Yikes!!!! Good thing this guy was right handed. If he were a lefty, he would have had his hand cut off at the wrist.

Call me paranoid, but I would never shoot anything but a low pressure load (Polywad vintagers, or my own hand loads) in any old gun no matter how thick the walls are. Any modern day factory load gets shot through a modern day gun.

Really one must think, rustic icons d'art first and shooters second with these olden ones.
After all, its always better to have 'em in one piece.

Dave K, 16gaugeguy's comment about "safe in any gun" was missed placed. I believe he was speaking about the psi in modern shells in general not in old guns. He has gotten in several long-winded debates about the dangers off using modern ammo in old doubles. I believe he is an engineer and preaches modern ammo in modern guns. However, nobody wants to believe their beloved double can go boom.

italiansxs, aka Jim - Easiest reference is probably the Winchester tables and graphs published in Butler's "The American Shotgun". You could look in Burrard also.

Any 'actual' graph of pressure vrs. distance will refute what you've been told quite easily.

Just ordered Federal's vintage loads from MidwayUSA. Consider me scared straight.

This is simply an old wifes tale that has been told for yrs. At least as early as the late 1920's DuPont ran a chart of 5 powders black, bulk smokeless & 3 dense smokeless powders from fast to the newly developed progressive (slow) which allowed them to load the heavy, High-Velocity loads we call Express, Super X, Hi-Power etc. "ALL" of these loads reached peak pressures within the chamber, from about 1-1½ inches from breech. Breech pressure has for yrs always been measured at the 1" point to ensure it didn't "Miss the Peak" as might happen if taken further away. One very good indicator of the max pressure occuring near the breech can be seen co-incidently from the gun-makers themselves. When smokeless powders began to replace Black, they didn't "Beef Up" the forward sections of their bbls, they "Beefed" up the breeches.
Note that in the DuPont test, of which I only have the data for 4 of the powders, all were loaded to the same balistics using 1¼oz of shot & a 3 dram or eqivelent powder charge. Al peaked within 8800-9800 psi from 1-1½", swapped positions @ 2½-2 3/4" had their max varition @ 4" of from 6000-7500psi & by 10" from breech were all back within 3400-3800psi. At every point past the chamber though the ones with highest max pressures now had the lowest, & vice-versa. Black had the 2nd lowest chamber & 2nd highest bbl pressure & 3FG was used, had 2FG, (often recommended for shotguns) been used it would have been closer to the slowest, most progressive smokeless used.
I noted the "Pressure chart" shown on that thread had no dimensions, no load identification & didn't even state what type of gun was being tested. Totally Useless "Non-Info".
This gun in question "Did Not" burst because the max pressure was too high, if it had, it would have a burst chamber just as did the Parkers Bell blew up @ about 30K pressure.

[quote=Mattkcc]Dave K, 16gaugeguy's comment about "safe in any gun" was missed placed." ?????????????

Mattkcc, is that like " I did not have sex with that women"?

here is a bit more from that keyboard cowboy who is a danger to all who read his post
16Gaugeguy;
"
If it was a black powder or pre WWI gun, I'd be careful. but your Sterlie was built to take it and will. Acceptable peak smokless shotgun ammo pressures have not changed much since that time. In fact smokless shotgun powders have actually gotten milder and slower over the last half century in the search for higher velocities and for use with magnum loads. Smokless powders like Red Dot, Green Dot, and Unique have been around for almost 100 years now.
I too tend to limit pressures on hinge guns for everyday use ammo like skeet and trap fodder. For hunting ammo, I'd not worry unless you are shootintg a lot of it all the time."




Come on,I don't care what he says he does,his quote is a very dangerous one and could and will get someone hurt or worse who reads it !There is NO defence for that