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Discussion Starter · #1 ·
My gun has markings on the barrels the word Choke is over17.7/18.4 on one barrel. On the other barrel the word Choke is over 18/18.4. Can anyone relate these numbers to the more typical terms for chokes? To the left of these markings sre the nMy gun has markings on the barrels the word Choke is over17.7/18.4 on one barrel. On the other barrel the word Choke is over 18/18.4. Can anyone relate these numbers to the more typical terms for chokes? To the left of these markings sre numbers 18.2 on both barrels.This a Spanish built 12 ga side by side that was imported by Richland Arms with G. Zapala on the barrel. It also has markings at the barrel mount as shown in the pictures.18.2 on both barrels.This a Spanish built 12 ga side by side that was imported by Richland Arms with G. Zapala on the barrel. It also has markings at the barrel mount as shown in the pictures
14581
14579
 

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According to a short internet visit to the Double Gun Forum, the first set of numbers indicate the choke diameter in millimeters, the second set of numbers indicate the bore diameter in millimeters. Multiplying the millimeter by .039375 ( or dividing the millimeter by 25.4) will convert the dimensions to inches. So--right barrel should be the more open choke 18mm choke .7088 and 18.4 bore .7245 equals a constriction of .01580. Left barrel should be the tighter choke, 17.7 mm bore .6977 and 18.4 bore equals a constriction of .0268. These constrictions, related in American terms, would indicate a very open modified choke on the right barrel, and mid range improved modified choke on the left barrel. Those settings should be about perfect for upland game I would think. 12-70 indicates a 2 3/4 inch chamber 70mm being 2.756 inches by the way. The right barrel would be the more open on all double shotguns except those built for driven birds, then the reverse is true.
 

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Those numbers are millimeters so subtract one from the other. There are simple online conversion charts to convert mm to in.
 

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Discussion Starter · #4 ·
According to a short internet visit to the Double Gun Forum, the first set of numbers indicate the choke diameter in millimeters, the second set of numbers indicate the bore diameter in millimeters. Multiplying the millimeter by .039375 ( or dividing the millimeter by 25.4) will convert the dimensions to inches. So--right barrel should be the more open choke 18mm choke .7088 and 18.4 bore .7245 equals a constriction of .01580. Left barrel should be the tighter choke, 17.7 mm bore .6977 and 18.4 bore equals a constriction of .0268. These constrictions, related in American terms, would indicate a very open modified choke on the right barrel, and mid range improved modified choke on the left barrel. Those settings should be about perfect for upland game I would think. 12-70 indicates a 2 3/4 inch chamber 70mm being 2.756 inches by the way. The right barrel would be the more open on all double shotguns except those built for driven birds, then the reverse is true.
Tnank you for that info. Much appreciated
 
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