Gorosabel and laurona choke.

huntinguy

huntinguy

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Markdale, ON
I have a gorosabel and laurona sxs and they have a bunch of numbers and symbols and I can’t make sense of this. Any help? First two are gorosabel and second two are laurona.




 
18.4 and 17.5 are bore and choke diameter in millimeters on one barrel.
The difference is 0.9 mm.
0.1 mm is approximately .004 thousandths of an inch constriction, about full choke.
Now you can do the math.
 
I recently went through the same exercise in deciphering the marks on my 16ga Pedro Gorosabel. Something I haven't yet quite found the answer to is why the same proof house (Eibar) would apply different proof pressures (e.g. 1000 kg/cm sq, 900 kg/cm sq, 850 kg/cm sq) to similar game guns (not "magnum proofed" guns) that are all stamped with the same 850 kg/cm sq (850 bar) proofmark (its the proofmark with the "BP" in it, most clearly seen on your Gorosabel)?
 
huntinguy said:
I was looking at this site. http://www.shotguns.se/html/spain.html
Yea trying to decipher the proof marks is confusing for me.
Click to expand...

Spanish proofing is even more confusing (I've been doing a lot of reading lately). It seems that the Spaniards maintained relatively low CIP proof standards while the Brits and Italians moved to higher CIP proofs to keep pace with the ammo industry, particularly developments in North American ammo which tended to be hotter.

I note that your Gorosabel 12 ga 3" was proofed at 1000 kg/cm sq and your Laurona 12 ga 2.75" at 900 kg/cm sq. If you follow the rule of thumb that service pressure should be kept about 25% below proof pressure, I don't think there is anything in a 12 ga 2.75" standard game load that would anywhere approach service pressure, never mind proof pressure.

However, when your guns were made, they also didn't have 21st century turkey or waterfowl loads in mind, and certainly not steel shot (which could further raise pressures in tight-choked guns like yours).

My suggestion would be to stay away from "magnum" 2.75" or 3" shells. Your guns might very well be able to take it, but without being proofed for such or without knowing how much the Spaniards might have over-engineered their guns, we just don't know.

Factory target, field or game loads; fire away!
 
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