I have a 12x12/9.3x74r Merkel from 1969 made in Suhl. The chokes are Imp Full and Imp Mod. and the barrel diameter is 18.3. After discussions with my smith, I feel IF and IM are too tight for slugs and OO buck.

I am looking to use this gun mainly for feral hogs and having the shot gun barrels loaded with OO buck or slugs would make a big difference.

So should I open the chokes?

thanks

Doug

I think you are going at it backwards. Instead of THINKING that the chokes have to be thus and such to utilize slugs and buckshot, you should be customizing them to do so. Begin where you are (and probably with Breneke) to see how it performs. It may be harder to get it to pattern buckshot than to regulate with slugs. The late Ralph Walker, in his book, "Shotgun Gunsmithing," describes getting shotguns to pattern well with buckshot. It was a matter of cut and try until performance was optimized. He recommended against OOO buck as he never could get it to pattern in any gun. Let someone do this kind of work for you or use rotary stones yourself on the last parallel section of the choke only, then shoot for pattern. It is not as hard as you might think. Do not lengthen forcing cones at the chamber unless you want the slug impact to drop a good 6 inches. Ask me how I know...Remember that the performance gained will be for THAT load, only. Change any variable and all bets are off! Good luck--Steve
P.S. Are you sure you wouldn't rather have a large caliber rifle insert for the purpose described?

Doug,
Steve gave you excellent advice.
Do not open the chokes, at least not before you thoroughly test them with all possible loads.
With kind regards,
Jani

Thanks for the advise...

I have not tried the drilling with the current chokes with slugs or OO buck. Is the concern that the chokes are to restrictive founded?

Many of the 12 ga. slugs marketed today are honkin' fast and high pressure. I recommend Breneke, and tamer ones at that for the tighter chokes, else a ring bulge behind the choke at muzzle could be a possibility, though a slight one. Buckshot is finicky and not so subject to constriction for safety reasons. Try it out for buckshot--the regulation for slugs will probably not be affected by choke very much. (lengthening forcing cones, YES) Your gun may be regulated for slugs NOW, from factory. One gentleman on the forum claims he gets 10" patterns at 40 yds. with his Sauer 3000...maybe you could research the choke configuration as well as constriction if that be so.

Ring Bulge? WTF is that-- HoJo scrubbin' the bathtubs at the Guiding Light Shelter on Beale Street and the rusty ring gets bigger, no matter how much "elbow grease" our pal Joey applies?

Lead is softer than steel, and cannot be hardened, like mild or alloyed steels can. A tight choke may Fubar the ballistics of a lead slug, but a ring bulge at the muzzle- BS-- I have a 1937 era M12 field 30" Full- and I have shot beaucoup buckshot and heavy steel shot through it for 30 years or more, hand runnin' and the concentric bore and choke is still 100% as it was the day it left New Haven CT.--

A friend has a special order Remington M31 12 gauge pump- 24" solid rib Full choke- .730" NBD and .035" constriction- and he can put Breneke slugs into a pie plate at 75 yards- offhand, shot after shot- just uses the front bead sight- no "tricked-up" rifle style sights or red-dot aimpoint scopes either-

If I were lucky enough to own a German merkel- I'd shoot it just the way it was made-and not "open the chokes" the old Masters tooled into it--

Ring bulges I have experienced have been with certain older, maybe milder steels--one an old Ferlach gun. I am not an expert on the steel in his 60's era gun, just describing what I have seen. That ferlach drilling got them on both barrels just by shooting plastic wads according to one gunsmith here in Dallas (of course, it was pretty old). My Funk drilling shows a tiny bit from the high power slugs I tested in it...sad! Briley would tell you that if you hammer certain plain old screw in chokes enough with steel shot, there will be a measurable swell--special hardened choke tubes are supposed to help. Bridging shot is a danger there. Metallurgy in newer barrels has been adjusted for steel shot. And yet I had an old side lock Sauer drilling made in 1927 that was indestructible--there is no telling how many slugs I poured through it. So I could go either way with anecdotal examples. I was trying to be sensitive to his concern that just any old slug might not be the best idea with his tight chokes. But the biggest concern was that he start where he was on finding out what constriction was best for buckshot, and go methodically from there.