I've noted the choke restriction/constriction? on a 12 ga is .005 each step..005-IC,.010 IC,etc.Does this hold true w/all gauges?One source said .004 for 16ga.I know this seems a bit esoteric,but I'm soon retiring and comtemplating amateur gunsmithing.Want to be sure of my facts.Another reason-I have a 12ga Jamart(mfgd Belgium) marked 18.3/18.4 on both bbls.Thought this meant 1-18.3 and 1-18.4.Not so.Found identical gun each bbl marked 18.2(dbl mod).Am looking for other gauge guns euro-made and need to figure choke.
Swampus,
Welcome to the bbs.
Jamart was around for a very long time. They produced some very nice guns.
The Belgian markings changed over time. After 1924 they used a single mark that denoted the bore only. Before that, they included the bore and choke in millimeters.
Here are the Belgian proof marks:
http://damascus-barrels.com/Belgian_All_Proofmarks.htmlSo, a barrel marked 18.4 18.3 would mean the bore was 18.4mm (0.7244) inches and the choked portion was 18.3mm (0.7205 inches). Or 0.0039 inches of constriction. Essentially a cylinder choked tube.
Pete
