Barrel Convergence Blues


Dear Bruce,

I want to set up a Perazzi MT-6 for Sporting clays. My questions is: How do you deal with the barrels not shoot to the same point of aim. I know of 3 MT-6 including my own that the top barrel shoots high and the bottom barrel shoots to center of P.O.I.

Pat

Dear Pat,

Well, non-convergence in barrels is a real problem. The MT-6s I’ve seen have screw chokes. If that’s the case with your gun, there really isn’t too much you can do economically to bring the POIs together. If it were a solid choke gun, you could have your choke maker remove some metal from one side of one choke to alter where it shoots or have Briley install screw chokes on a bias. Yes, they will do that.

If your MT-6 has split barrels, as most do, you might be able to have an experienced gunsmith remove the front hanger/stub rib and resolder it closer together to adjust the POI. It’s sort of a cut and paste approach, but relaying the ribs is the classic way to correct non-convergence if you don’t want to get into the chokes. Krieghoff has a big advantage here as you can just replace barrel hangers to get what you want.

You could also install eccentric choke tubes in place of the ones you have. Briley will make them for you. It’s a real pain though as they can only go in one particular barrel and have to be indexed correctly.

Or you could sell the gun. I had a Perazzi Comp I that shot the top barrel slightly over a full pattern higher than the bottom barrel at 40 yards. I also had a Superposed that did the same thing. And a Parker Repro that shot the left barrel far left. I sold the two O/Us without attempting alterations. I had the chokes reworked on the Repro to bring the patterns together. Worked perfectly. Then I sold the gun for dwarf stock reasons.

That’s one of the reasons I prefer to buy a used gun to a new one. The first thing I test a used gun for is barrel convergence. If it flunks that test, back it goes. Just about everything else to do with POI and gun fit can be fixed, but it’s more of a pain to adjust convergence, especially if the gun already has screw chokes or has extremely open fixed chokes with little metal left to remove.

I wish there was an easier solution, but I don’t know of it. Just make sure that you have tested your gun properly for convergence. Often shells of different strengths will vary in convergence. That’s a possible solution. Also, the way you hold the gun when you shoot can influence convergence. A light forehand hold will allow the top barrel to shoot higher than a tight forehand hold. Still, there’s not point in altering the way you shoot just to correct some problem with the gun.

O/U basic design “wants” to shoot the top barrel high because the top barrel is on a higher axis than the bottom. Rather than regulate that out, some Perazzis I’ve seen have been set up to shoot the top barrel first, high, and then the bottom barrel second, flat. In many trap situations that will work. Of course, in SC it won’t.

Bottom line: I don’t have an economical and practical answer for you or for myself when I ran into this problem. Sometimes a dog just won’t hunt.

Best regards,

Bruce Buck
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)

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