Help please with Belgium .410 proof markings

[sir jasper]

Need some help identifying/understanding the pressure proof of a Belgium single barrel folding .410 circa 1957ish...

 

On the barrel is the lion & P.V. marking so it's nitro proofed, but I'm struggling with the pressure rating.

 

I believe the stamp that corresponds to the pressure reads:

 

0-kg 664 ɤ

 

Does this indicate a max pressure of 664 kg per cm? If so, who makes .410 cartridges with an appropriate pressure rating; the 2" 5/16 oz Eley Fourten cartridges that I have are rated at 900 kg per cm.

Edited March 26, 2013 by sir jasper

[sir jasper]

Update:

 

It looks as though the "0-kg 664 ɤ" stamp indicates the weight of the proofed barrel, not the maximum service load.

 

Couple of questions:

There doesn't appear to be any indication of maximum service load - can anyone tell me if this is this unusual?

If there's no max service load stamp, is the 2 1/2" chamber an indicator that any modern 2 1/2" cartridge can be shot?

[sir jasper]

Update II:

 

Looks as though my 2" Eley cartridges will be fine; found the following text on the "fourten" website:

 

"Originally the .410 was designed to fire a 2 in. cartridge loaded with approximately 5/16 oz. of shot. Later weapons were produced to handle a longer 2½ in. cartridge load with 7/16 oz. or, as is common today, ½ oz. of shot. Most modern .410's are chambered for 3 in. cartridges which can be loaded with up to ¾ oz. I am not keen on the 3in. cartridge, its long shot column and the very high pressures produced are not conducive to good pattern quality"

[Andy H]

If your chamber is 2 1/2" then any modern 2 1/2" should be suitable in a 1957 vintage 410.

[wymberley]

There doesn't appear to be any indication of maximum service load - can anyone tell me if this is this unusual?

If there's no max service load stamp, is the 2 1/2" chamber an indicator that any modern 2 1/2" cartridge can be shot?

I DON'T KNOW FOR SURE but a max service load may be related to the proof marks (and, I would imagine, chamber lengths). Prior to 1968 there were two marks for nitro powder. The one you mention is Nitro Proof and the other - with a crown replacing the lion - is Nitro Superior Proof. This system continued after 1968 but the marks are entirely different

[sir jasper]

If your chamber is 2 1/2" then any modern 2 1/2" should be suitable in a 1957 vintage 410.

 

Andy,

I've come to the same conclusion, but If I buy 2 1/2" cartridges I'll stick to the lighter 2 1/2" 12.5gms (7/16oz) loads.

Edited March 28, 2013 by sir jasper

[sir jasper]

I DON'T KNOW FOR SURE but a max service load may be related to the proof marks (and, I would imagine, chamber lengths). Prior to 1968 there were two marks for nitro powder. The one you mention is Nitro Proof and the other - with a crown replacing the lion - is Nitro Superior Proof. This system continued after 1968 but the marks are entirely different

 

That's what I thought, but I can't find a pressure rating relating to the nitro proof stamp on my .410 (lion over the letters P.V.). I did however find a rating for the Superior smokeless proof you mention (crown over P.V.) - 17,600 psi for 16 gauge and larger. 20,000 psi for smaller gauges.

[ajtrader]

Hi Sir Jasper,

 

The Lion over the letters P.V. = Smokeless powder proof (p.v. = poudre vive)

 

See the following link - Old proof marking European shot guns