I am often wondering what the relative chokes are in gauges other that 12 ga and found this in my files. THought it would be of interest.

[img:left][/img]

Thank you Stallones. Very handy to print out and keep at the workbench.

-jmc

Don't think I'd ever seen the #1 comment under miscellaneous on that chart. I don't think that is true for British guns.

Bob,I think they are referring to modern European bores.
My Renato Gambas both have .723-.725 bores

Some Italian guns are underbored. My 40 year old Bernardelli is just a little tighter than Stallones' Gambas.

Although the Brit 12ga standard is .729, their 16ga standard is .662, which is smaller than the figure given.

I think the "True Bore Diameter" term here is an attempt to try to define what the makers use.

"True Gauge" by the formula of what a bore size pure lead ball weighs is 10ga = .775", 12ga = .729", 16ga = .662". 20ga = .615", 28ga = .550" & a .67.49ga = .410". These sizes are recorded by the proof houses.

The old full choke reduction of .040 in a 12 gave an 11% reduction of bore size, a more modern one of .030" gives a reduction of 8%. Lesser constrictions of course give lesser %.

They sort of shifted the Full constriction when shot collars and wads started producing tighter patterns with the same constriction. Full choke for a 12 gauge was 0.040" constriction for a loooong time.

Stan's chart was produced by Colonial Arms choke tubes.

Here's some more...











Teague Chokes

Some old charts I've seen for 12ga the chokes go by .005 -sk/.005 , Ic/.010 , LM/.015 and so forth. Why is it when going from IM/.025 to full it jumps by .010 on some charts ? In one old chart full is .030 - as it should be IMHO. Paul

Look at the Briley Chart....they stay with .005 increments.

Check out the Maker's chart. Some use 35 pts, most of them use 40 pts for full and at a glance I don't see anybody claiming Full with 30 pts.

Mike, at .030 they list a LF, not Full. Why would all the others go by .005, but Full has to jump by .010 ? I have a chart in our shotgun room at my club that shows only a .005 jump from IM to Full but don't know where it came from. It's a older chart and doesn't list LF. I don't remember seeing the term LF till all these turkey chokes tubes came out. Back in the day before choke tubes there were chokes at .040 and more but believe they were just call full or extra full. Now with tubes we have LF, Full, Extra Full, and Turkey. I just shoot the old SxS's and have different ones with different chokes. One of these days I'm gonna bring 10 of them out to the club and put one at each station on SC's. Then I can tell the guys how I need different chokes and look here - the right gun is at the right station.

Paul,

What is the jump from IC to MOD?

The variation in the charts just hammers home the point that the best way to discuss choke is with measurements, not nicknames.

Remember..."directions are just one man's opinion."