doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Explain German Proofmarks

Can you help with the explanation of each of these marks ? Thanks, Daryl

1/24 means the barrels were proofed january 1924...

the rest of the stamps on the barrels are of little significance...

except for the world nitro, which is confirmation that the barrels were proofed with high pressure smokeless powder...

and not low pressure black powder...

plus, the Krupp steel stamps on the barrels indicate that the barrels will typically withstand up to five times the typical proof pressure...

I read somewhere that under destructive testing Krupp barrels began to bulge at around 90,000 psi...

the following thread on the subject is worth reading...

https://www.trapshooters.com/threads/how-much-lup-does-it-actually-take-to-blow-up-a-gun.935617/

ed: would you please share the source of the Krupp 90,000 psi bulging report? The 5X proof pressure? Which is not part of that Trapshooters.com thread to which I contributed. Tom Roster blew an 870 barrel at 55,000 psi BTW.

Krupp Fluss Stahl (Homogeneous Fluid Steel) was introduced about 1890 and I have found no published data regarding tensile strength, but composition suggests it was similar to AISI 1045 which would have a standard tensile strength of 85,000 - 90,000 psi
Krupp Nickel Steel patented in 1890 does have published strength at 92,500 psi
https://www.doublegunshop.com/forum...p;Board=1&main=13559&type=thread

Dennis Potter contributed a Krupp Essen barrel segment to my tensile strength study. Unfortunately, it was from an unknown gun and DOM. I did not do a composition analysis, but the tensile strength was 113,000 psi

Tensile strength is only part of the pressure cylinder bursting formula however

Barlow's formula P = 2 x S x t / D
P=Bursting pressure in psi.
S=Tensile strength of material in tube wall.
t=Wall thickness in inches.
D=Outside diameter in inches.

Burrard used the Alger Burst Formula
Burst pressure = Ultimate tensile strength x 3(OD – ID) / OD + 2xID

Neither work for an unobstructed shotgun barrel ie. open at one end.

Daryl, that kapital letter "W" stands for Würgerbohrung and that is that the barrel have a choke boring.
Cheers, Marc.

I don't know how insignificant knowing it was/is chambered for 2 1/2 in. shells rather than the more modern 2 3/4. That's what the circled 16 denotes, 2 1/2 in. shells.

drew, going from memory only...

read it some where, some time...

sharps, re chamber lengths in pre ww2 guns...

regardless of what's stamped on barrels, employ gunsmith to measure chamber lengths and barrel wall thicknesses in front of chambers and behind choke forcing cones...

my gunsmiths general guides lines are no less than .090 in front of chambers and no less than .030 behind choke cones...

and ask your gunsmith his opinion re safe shooting of any old guns...

Remarkable scholarship.

Let make it clear for each and every one. The only compleet book about proof marks is written in German a full 204 pages little book Written by Gerhard Wirnsberger
There is no need to have a compleet knowledge about German, with a little "google translater" it is clear.
Cheers, Marc, greetings from Belgium.