doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Minimum barrel wall thickness?

shooting a damascus barreled gun with minimum wall thickness of.020 11" from the muzzle sounds risky to me...shooting it with any smokeless load sounds foolish to me...why take the risk at all? hang it back on the wall...

Ed, to say shoot the gun with black powder is stupid. Pressure is pressure, no matter what type of powder is used. 6,000 psi with black is 6,000 psi with nitro. Both are 6,000 psi. Perhaps the peak is reached an inch further down the barrel. Perhaps it differs a few hundred psi someplace. But either a barrel is safe to shoot with any type powder or not. To say use only black powder is just as dumb as say to not use high brass shells in a gun. The height of brass does not tell you pressure.

ky: we are in agreement...the safest decision is not to shoot hit at awl...hang hit back on duh wall...

It will all depend on the material the barrel is made of . Some "steels" will be fine at .020".Some will not .
There are many hundreds of guns shot every day with thin walls without indecent .As there are many cars driven in non roadworthy condition without accident or injury.
But one day the barrel might burst .Its a risk and its up to you to take that risk and the responsibility for it .
I could advise you based on long experience , having examined the gun ,I could advise you on charges and loads , but thats all it is advice .Its up to you to take that advice , but its up to you that if unsure not to use it ,which is always the safest option .

Agree. At one time, there was an old wives' tale about significantly different pressure curves for black vs smokeless. Dupont charts, pre-WWII, showed that there's not that much difference. So did tests Sherman Bell ran in his "Finding Out for Myself" series in Double Gun Journal.

John Brindle, The Double Gun Journal, �Black Powder & Smokeless, Damascus & Steel�; Volume 5, Issue 3, 1994, �Some Modern Fallacies Part 5�:
The pressures produced in the breechloader by black powder, as black powder was actually loaded at the end of the 19th century, were not significantly lower than those given by smokeless (then often termed �semi-smokeless�) powders developed as a substitute for, and an improvement on, black powder.

From a 1895 study published in The Field for 1 1/8 oz. 3 Dr. Eq. @ 1222 fps, converted to psi with Burrard's formula
72 gr. Curtis & Harvey's No. 2 T.S. (somewhat similar to FFFg) = 3.2 Tons = 9,632 psi
82 Gr C&H No. 4 T.S. (similar to FFg) = 2.26 Tons = 6,474 psi
84 gr. C&H No. 6 T.S. (similar to Fg) = 2.1 Tons = 5,936 psi

1 1/8 oz. 3 Drams (1200 fps) of DuPont FFFg (82 grains) is about 5000 psi
Black Powder substitute pressures from the 2001 �Lyman Black Powder Handbook & Loading Manual�
1 1/8 oz. with 100 gr. GOEX FFg at 1200 fps = 4,800 psi
1 1/8 oz. with 100 gr. Pyrodex RS at 1200 fps = 5,600 psi

As Larry said the pressure curves run by DuPont in the 1920s do show very similar curves for all powders tested. With shells loaded to give the same shot charge the same velocity, those loaded with Infallible, Ballistite & Dupont Bulk Smokeless showed a higher "Breech" (Max Chamber) pressure than 3f Black, but a slightly "Lower" pressure for the rest of the barrel.

DuPont Oval, one of our First "Progressive" powders show a lower max pressure than even the black, but a slightly higher barrel pressure.

The bottom line is "IF" you give the same shot load the same velocity, you have done the same work. This translates into the Fact, that the average pressure for the entire length of the barrel is essentially the same, It is just slightly re-distributed.

The Major difference in Black & Smokeless is that black burns at very much the same speed regardless of circumstances. Also due to the space it occupies it is near impossible to Overload with black. It is Highly suspected that many barrels were burst in the early days of smokeless by Re-loaders who Measured their Dense smokeless powder with the same bulk dipper they had used for Black &/or Bulk powders. This would give from a double to a triple charge of these dense powders, took a strong gun indeed to hold such pressure, whether Steel, Twist or Damascus made little difference they all Burst under these loads.

If I have a gun, with barrels as thin as .020 at 24" from the breech and they look perfect, without pitting in the area, I will shoot them with sane loads. Where they are thin is just as important as how thin they are. The closer to fleshy parts, I do not want to loose, the more unlikely I will be to shoot the gun. One with thin areas in the first 20" are not high on my list of guns to shoot. It is location, location, location, with all other things being the same.

Guns fail because people shoot them. They shoot them without finding defects. They shoot them with obstructions in the bores. They shoot them with loads which to me are insane. Do that and you are tempting failure every time. But if you use reasonable precautions your risk will be very, very small. But all shooting is a risk to some degree.

I've seen several K-80's that blew up. One which I am 100% certain did so with never having seen a reloaded shell in it's life. Two month old gun, just let go. Owner has more money than I dream of and has never reloaded a single shell in his life. Must be nice. Most likely cause was determined to be the base wad of a AA factory shell becoming lodged in the bore to create an obstruction. Nobody admitted fault, nobody could prove it for 100% but that was the most likely outcome. The owner just bought a second set of barrels. Don't know what he ended up doing with the first set. Mentioned he was going to have them tested by a Lab. He does not use AA ammo anymore though.