doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Charles Masquelier Double 12

Re standard bore diameter for a 12ga, it should be .729-.730. Thus your readings at the muzzle should indicate .035 and .037 constriction, which would be full choke in both barrels . . . unless I'm missing something here.

Cavasback, no worries whatsoever. Although I've used firearms extensively in my life and through this the twilight of a forty year career in Law Enforcement I learn and find I have to learn something each day. And I absolutely recognize my limited knowledge of these old doubles. Thanks for your response and your input is well received Sir.

L. Brown, this is the area where I'm not fully conversant is how the "choke" of a shotgun is determined and I never really paid attention beyond simply what was stamped on barrels or choke tubes. I've read that 18.5 mm is considered Typical or average and if so, if I'm correct that translates to .728. It's hard to trust what we read on the internet like lots of things so try to get as much information as I can from multiple sources. Based on the 18.2 or even the 18.3 stamped on the barrel is how I arrived at the is how I arrived at the differences. But I have no way to truly get an accurate measurement of the actual bore diameter on this shotgun. I didn't realize how little I knew about chokes on shotguns until I bought this one a few days ago and still feel pretty inept on the topic. Thanks so much for your replies Sir.

I'm still trying to learn my way around using this forum format. At risk of posting too much especially for being new here, I wanted to reply to your comment. In my past I reloaded for a .300 Magnum rifle I had but never ventured beyond that. I do have good friends who reload these days but most I know, don't load for shotguns. I'm willing to invest in whatever I need and have recently wanted to start reloading for a Savage Model 99 in .308. I have the equipment to reload for rifles but I would be starting almost from ground up with shot shells with all that said, it would be just another learning curve. Reloading for a shotgun always seemed a little more daunting to me than for rifles or handguns. Maybe it's getting a professional looking crimp that I remember thinking was the trick. But will consider setting up to learn reloading. As stated elsewhere, thanks to each member here who had the patience and took the time to answer my questions.

I'll just say I arrived here, at this site, about 15 years ago, on the advice of my gunsmith, as a complete ignoramus when it came to shotguns other than my M12 and my 870. And I didn't know much about them. LOL.

Not quite but just about everything I've learned about vintage SxS, including their care and feeding, came from this site and a collection of the Double Gun Journal. If you want to learn, this is the right place.

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Reloading for a shotgun is not particularly challenging. People who know me would tell you that if I can do it, then it doesn't take a lot of mechanical skill. Some go so far as to tell me that I'm dangerous with anything more complex than a screwdriver in my hands.

That being said, let me go back to your question about determining choke. It is actually very easy, but you do need the right tool to do it right. When I first started out, I had a drop in bore gauge. Drop it in from the muzzle and you get a choke reading. But that only works if you're starting out with a shotgun that has a standard bore diameter. The tool that does the job accurately is a bore and choke gauge. Not all that complex, but far more accurate than the drop in gauge I used initially. You will find plenty of shotguns--especially older ones-- with a bore that doesn't have the standard diameter of .729-.730 (if it's a 12ga.) The bore and choke gauge has a dial on one end attached to a rod which goes into the bore from the muzzle. The rod has a head on it which measures bore diameter which you read on the gauge. Then you simply slide the tool out of the barrel, and as you get closer to the muzzle, the reading will begin to change, showing constriction. Which we call choke. You can find all sorts of charts, mostly fairly accurate, which tell you how much constriction equates to what choke on a gun of the gauge in question. The smaller the bore, the less constriction is required to produce the same degree of choke. For example, while anything in the 30 thousandths range would be full choke in as 12 gauge, you only need about 25 thousandths constriction to give you full choke in a 20 gauge. Most of us do have to refer to choke charts in order to remember what is modified on a 16ga, for example, compared to a 12 or a 20. Just remember that choke is the difference between bore diameter before constriction begins to take place and what your gauge reads as you pull it out of the muzzle.