doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Determining Choke on 1935 Francotte 16 ga

Newbie here.

I recently inherited a grade 20E Francotte 16 ga. dbl barrel shotgun (A&F). I am unfamiliar with how the chokes are indicated on the barrels and was wondering if any of you could help me out.

The gun came with three sets of barrels - two are original and one was made in 1964. I have confirmed the various proof marks using your Belgian gun database (it�s very helpful - thank you) but just can�t seem to figure out the choke designation.

The three barrels are labeled thusly: #1: "16.9 choke 16.8" on both barrels; #2: "17.0 choke 16.9" on both barrels; and, #3: RB "17.0 choke 16.9" and LB "17.2 choke 16.9".

The thing that confuses me is, for example, on gun #3 it appears that the choke is larger than the bore or the gun has two different bore sizes both choked sown to 16.9.

The other thing that is confusing is that when I use a micrometer on the muzzle end of the #3 barrels I get: RB 16.8 and LB 17.0. It�s all very confusing.

Can any of you help me out? Many thanks.

P.S. I have talked with Bob Beach and am waiting for his report.

I'd forsake all those constriction numbers and pattern it with a couple different sizes of shot, large & small. Now that will be your empirical choke. What is on the tubes is constriction, i.e. the term choke just notes constriction.

Cheers,

Raimey
rse

Good advice Raimey and I plan to do that but from a learning perspective I'm curious about what the actual markings meant when the gun was made. For example, on barrel #3, for the RB ("17.0 choke 16.9") does it mean a 17.0mm bore choked down to 16.9 mm with the LB ("17.2 choke 16.9") being 17.2mm bore choked down to 16.9mm? Seems strange to have different bore sizes (neither of which are nominal for a 16 ga.) choked down to the same choke, which is pretty much a nominal 16 ga bore. If it is the other way around then the barrels are starting off with nominal 16 ga. bores but are choked more open and not more constricted.

In any event, I know I need to pattern the barrels but I'm trying to learn about the various sets of barrels' markings and what they meant when the gun was made. Many thanks for your reply.

I would have to dig out my books to see for sure when changes occurred but Belgian marks changed over the years as regards to choke. At some point in time chokes were marked by giving a bore size plus choke size. At other points in time the barrels were simply marked "Choke" if they had at least .2mm (.008") of restriction. what you are likely encountering on these barrels is they were marked at provisional proof & then polished some prior to final proof at which time they were re-marked with the slightly larger size, has nothing to do with the chokes.

Yes, for the exercise in futility, you'll need to follow the proof rules/protocol. A measurement @ 22cm(or similar) and a bit from the muzzle but as 2-piper notes windage & final polishing will result in a variation.

Cheers,

Raimey
rse

After 1924 the markings were simply "Choke" and bore
http://shotguns.se/html/belgium.html

Pre-1924

Just get it measured ! No telling what has been done to it in the last 80 years .How would you know if the original markings still stand or were in fact accurate .