Italian breech stamps

[George]

I don’t speak Italian, but I’m trying to learn some Italian math. Italian replica shotgun barrels have some confusing numbers stamped on the breech, and I know they would provide us with some useful info if only we could read them. Turns out, I think the problem is that we in the USA never learn to speak metric, but that’s what the Italians use. I’ve been playing with this and thought there might be some interest in discussing the topic.

Here are two Italian SxS percussion shotguns, the first by Pedersoli, the second by Pietta.

Notice that both guns are stamped 18.3 or 18,3. That’s the gauge designator, stated in millimeters. One inch is equal to 25.4 mm, so 18.3 mm is equal to 18.3 ÷ 25.4 or .7205 inch. I believe that is the size Italians use for 12 gauge, and these stamps indicate both guns are 12 gauge exclusive of choke. If you have a gun stamped 18.3, that designates the ID of the basic tube, and you can tell if it’s cylinder or choked by simply measuring the muzzles. If they measure .720” they are cylinder, if anything smaller they are choked.

Each barrel is also stamped with what I interpret as a proof pressure stamp. The Pedersoli barrels are marked KG1,320 and the Pietta KG1,920. Once again, we need to convert from the metric. Where we say “pounds per square inch”, metric speakers say “kilograms per square centimeter, so that KG1,920 means 1,900 kilograms per square centimeter. One kilogram equals 2.2 pounds, so it also says 2.2 x 1,920 or 4224 pounds per square centimeter. One square inch equals 6.4516 square centimeters, so we have 4224 x 6.4516 or 27,251.56 pounds per square inch.

Doing the same exercise for the Pedersoli we would find that it has been proofed to 18,735 psi.

Anyone out there speak metric Italian? Am I on the right track?

Spence

 

[pargent]

Agree with you on the bore and pressure calulations, but as you know the barrels were proofed with higher pressures . :thumbsup:

 

[George]

.... as you know the barrels were proofed with higher pressures.

Not sure what you mean by that.

Spence

 

[pargent]

For modern pressure tests it is sop to test a vessel (for want of a general word ) to say eg . 20,000 psi then give it a pressure rating of 15,000 psi, this is to give the rated part , barrel ,vessel etc a built in safty facter for excess pressure spikes.The stamped on rating is 15,000 for that component.

 

[pargent]

It's not so much as a liability thing as a saftey thing and it is relevent to all rated equipment so that the operater can operate the piece of equipment at max rating with out fear of damage to the equipment or operater or by standers . It applies to proofed guns, liftinggear cranes chains ,cables , scaffolding and the list goes on .

 

[George]

I understand the concept, but I'm confused why, if that's the case here, they would stamp the barrels with such a specific number, 1,920. Why not 1,900, or 2,000?

Spence

 

[pargent]

A shot in the dark,pardon the pun , but I think it has to do with the metric units of measure. When we use psi we can round of easily because 1psi is not a lot of presure 1 of the metric units will be a broader measurement and thats why they have what appears to us as an odd rating. That is how I see it. :hmm:

 

[jdkerstetter]

Hey Spence,

While the C.I.P. Proof House (which most European manufactures use under agreement) proof data for center fire arms is readily available, the requirements for muzzleloading arms is a little harder to find.

It is my understanding that barrels made in countries who use the C.I.P. Proof Houses have the actual pressures used for testing stamped on them.

I sources I have seen indicate that the minimum acceptable standard for proof on muzzleloading black powder arms is 700kpcm2 as is used on the majority of Spanish arms imported to the U.S.

This, of course, doesn't mean that the barrels will fail at higher pressures and this is demonstrated by those shooting three 50grn "pellets" in their magic magnum modern muzzleloaders.

Your barrels being tested to 920 is significantly higher (probably at the request of the manufacturer, which is allowed by the C.I.P.) and I would feel confident that they are quite safe.

Enjoy, J.D.

 

[George]

I sources I have seen indicate that the minimum acceptable standard for proof on muzzleloading black powder arms is 700kpcm2 as is used on the majority of Spanish arms imported to the U.S.



Your barrels being tested to 920 is significantly higher (probably at the request of the manufacturer, which is allowed by the C.I.P.) and I would feel confident that they are quite safe.

I'm not following your line of thought, I suspect, J.D. What's the relevance of the "700kpcm2" figure? Neither of my guns are stamped in those units. Even if your assumption that one of my guns is safe because it was tested to 920kpcm2 was valid, what about the other at 320, if the minimum allowable is 700?

As far as I can decipher, my guns are marked "KG-1,920" and "KG-1,320", not "KGI-920" and "KGI-320". They definitely aren't marked with either KGF or KP to indicate kiloponds.

I'm not concerned with the safety of the guns, only trying to understand the markings.

Spence

 

[Golfswithwolves]

Mr. George- I wonder if the KG markings are indicating the weight of the barrels. The proof markings as I understand it are generally the odd pictures on the barrel.

 

[Golfswithwolves]

Mr. George- Further looking into the marks suggests to me that the actual proof marks are the ones with the little flower or star with a border around it; PN for the initial proof marks and PNF or Finito for the final proofing.

 

[Ike Godsey]

18,3mm is the official caliber stamp.
PN stands for "poudre noire" = blackpowder, and the little stamp with the circled star over it shows that this is an italian proof.

you might look here for the country of proof.

1,930 is the pressure.

as one said before, these are CIP signs. on CIP, you might notice that a smoothbore is generally a "shot gun" so those are not proofed with musketballs, but with a heavy load of lead shoot. the weight depends on the boresize. also the powdercharge depends on boresizes.

hope that helps.

ike

 

[George]

Thanks, Ike, that does help. I was hoping someone from Europe would speak up.

Spence

 

[jdkerstetter]

Sorry, got a little caught up in all the numbers. Confused myself jumping around with the research and then back to the post. The KPCM2 measurements are not applicable here.

Ike is correct, the KG#'s are the actual pressures to which proof was preformed in this case.

Enjoy, J.D.

 

[Golfswithwolves]

Out of curiosity I weighed the barrels of my own Pietta SXS, which has a marking of KG 1,990 (a European style of writing 1.990 Kg). My barrels weighed 1.950 Kg. but have had a bit of steel removed from jug choking. I would be interested to know whether other folks got similar results from weighing out their barrels or if my results are just a coincidence.

 

[Ike Godsey]

Thanks, Ike, that does help. I was hoping someone from Europe would speak up.

Spence

you're welcome.
i on't know if you know german or if you have anyone "on hand" to translate german writing, but here is a document (.pdf) that describes what and the way a gun has to be proofed here in germany. on page 27 at point 2.1.3 there is written about the proof of blackpowder guns.

example:
i personally use a 12 ga (.72 cal) smoothie.
here it is assumed that a "normal load" for a 12GA would be 6,5 gramm (not grain!) blackpowder and a 36 gramm (again not grain!) load of shot. so the proof load is 13 gramm blackpowder and 65 gramm shot.

hope that would be helpful.

ike

 

[George]

Easy to do, J.D., it's sort of like deciphering hieroglyphics.

So we have shotgun barrels with proof marks indicating the actual pressures they were tested at. That's very different than proof marks in the old days, which only indicated that they had been tested according to certain agreed-upon standards, and had passed.

And, two sets of Italian 12 gauge barrels, one tested to ~30% higher pressures than the other. Well, I'm glad to have learned to read the marks a little better. Understanding how it all fits together, I suspect that is a bigger job, but I'm not going to let it interfere with my rabbit hunting :grin: .

Spence

 

[Ike Godsey]

oh i forgot to mention, blackpowder got a maximum pressure at 800 bar - which is 11603,02 psi.

 

[George]

here it is assumed that a "normal load" for a 12GA would be 6,5 gramm (not grain!) blackpowder and a 36 gramm (again not grain!) load of shot. so the proof load is 13 gramm blackpowder and 65 gramm shot.

So a normal load is considered 100 grains of powder and 1 1/4 oz. of shot, and a proof load would be 200 grains powder and 2 1/2 oz. of shot.... did I get that right?

Spence

 

[George]

oh i forgot to mention, blackpowder got a maximum pressure at 800 bar - which is 11603,02 psi.

I don't understand that one, Ike. In what situation is the maximum for black powder 800 bar? Can you explain it from another point of view?

Spence