Masquelier SXS choke size

[Old Ghillie]

I have a 20 ga. C Masquelier, Liege, shotgun with both barrels marked "choke 158".
This was made in Belgium during the period 1925 to 1956 to compete with
the English doubles of that period and is a quality gun.
I have been unable to determine what restriction that would be.
Can anyone help me??
Thanks, Gary

 

[Londonshooter]

I believe 15.8 is your bore diameter in mm. Would have to convert that to thousandth of an inch ( = 622 thou). Measure your muzzle diameter, subtract that from 622, and there's your constriction. Google 20 gauge choke restriction table and find what your chokes are.
Or measure your pattern by shooting it and counting pellets would give you the effective choke.

 

[Old Ghillie]

Thanks for the information, Gary

 

[Old Ghillie]

Another question.
If the choke diameter is 15.8 and the diameter of a 20 gauge barrel is 15.6 wouldn't that
indicate "cylinder"?
Gary

 

[gunsaholic]

15.8 is not the choke diameter, that is the bore measurement of your particular set of barrels when made. The word choke on many of these guns is just indicating that the muzzles have some kind of choke constriction, it isn't really saying what that constriction is unless there is another number stamped on each barrel. Say it was marked 15.8 and 15.2, then that would mean the bore size is 15.8 and the muzzle is 15.2 which would be the choke constriction. If yours only say 15.8, then it is indicating the bore size and you would have to measure the muzzles to know the actual constriction.

 

[Old Ghillie]

My thanks, seems right, I will check the muzzle measurement.
Gary

 

[Melvin]

Sometime in the proof mark history of Belgian guns they could have two numbers on the barrels. One was the provisional proof bore diameter and they other was the final finished proofed bore diameter. Some think the two numbers are the choke and bore diameters but, as mentioned in another post the word choke means the muzzle has choke not the smaller measurement is the choke. The smaller number would be the bore diameter measured before the gun was finished, possibly polished etc. I believe the provisional proof was done to avoid a bunch of finishing work on a set of barrels that did not prove at the end?