doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Problem: O/U Barrel Regulation

Problem Statement : I purchased a B. Rizzini, 20 Ga., O/U shotgun - but, failed to definitively pattern the gun for barrel regulation before the warrenty expired. Now, after careful testing, it appears that the upper barrel's point of impact is approximately 16 inches higher than that for the lower barrel at 40 yards. The lower barrel's point of impact seems well aligned ("centered")at 40 yards with the "normal" site picture. This differential in the points of impact for the two barrels appears to be unacceptably large.

There appear to be two possible solutions.

1. Connecticut Shotgun (who represents Rizzini in the US) gratiously offered to provide new barrels at their cost plus the action/barrel fitting fee. But, I have no response to my inquiry concerning the specification for regulation of the new barrels which can be anticipated or guaranteed. Do other members of the forum have information / standards / specifications for point-of-impact barrel regulation which can be expected from "good" double guns? I understand that perfect superposition of the two patterns of a double gun is unrealistic - but, what is a reasonable expectaion for the differential in the points of impact for the barrels?

2. I contacted Briley manufacturing with respect to the manufacture of compensating, screw-in, chokes to correct the point of impact problem with the upper barrel. In this case the bore of the choke is angled with respect to the barrel bore to compensate for the barrel's misalignment. Briley seems confident in achieving a good technical solution to the problem. In my opinion the required compensating angle may "push" the physically possible, choke geometry, modifications.
Do other members of the forum have experience with this type of compensating choke modification? Are the patterns created by these compensating chokes as good as those produced with standard, uncompensated, chokes?

Thanks for your help with these questions.

Don Henderson

Don,
It sounds like the gun isn't fit well to you to get that top barrel to shoot for you. Try having someone you trust as a good gunner but of different body shape than you give the pattern testing a try.

While you may have a gun with bad POI match barrels, the gun should shoot the top barrel at your point of aim. That gun either doesn't fit you well or the top barrel has a problem.

I have a friend who had the same issue with his Rizzini clays gun. He struggled with it for a least a year before arriving at a diagnosis. This spring he had it "Eysterized." After his session at Eysters he's turned into a patterning maniac. He also quickly made master class now that his gun shoots straight and he's been tearing up the tournament circuit. In fact, he just kicked our butts and took HOA again yesterday.

Chuck,
I was with Don when he did some of the testing for barrel regulation on his Rizzini O/U 20 gauge. I don't believe gun fit has anything to do w/ the the barrel regulation. The same sight picture was used w/ each shot. Points of impact being high/low, right/left, for both barrels would be indicative of Poor gun fit, but not one barrel relative to the other given the same sight picture is used for firing both barrels.

Chuck --

I understand your argument with respect to the point of impact for the upper barrel vs. the lower barrel. But, in point of fact the upper barrel does shoot high. Roger (see Roger's reply) and I undertook extensive testing. We considered barrel heating. We exchanged chokes between barrels. We both shot the gun. All these experiments lead to the same conclusion. There is a substantial divergence in the point of impact for the barrels.

Best Regards,

Don

Mike --

Thanks.

I found your reply very interesting --- particularly since I do not recognize the term "Eysterized". To what does this term refer? Is this a choke manufacturer?

Best Regards,

Don

No arguement Don. It sounds like you identified the problem.

I think Mike is referring to Ken Eyster.

Ken Eyster Gunsmiths Inc
6441 Bishop Rd
Centerburg, OH 43011

Thanks, Chuck.

Indeed, I did find a reference to Ken Eyster in a Google search.

I may try contacting Eyster to discuss the problem.

Best Regards,

Don

Don,

Chuck is right. There are 3 reknown shotgun barrel men that come to mind. I'm not really intimate with their services, but the impression I have is that Stan Baker was a guru of overboring (a lot of skeet guns?), Ken Eyster barrel regulation via choke alteration, and Tom Wilkinson overboring and choking trap guns. I imagine any of them could do it all, that's just what I remember. I had Tom backbore some barrels and the workmanship was superb. These guys are also of the old school of tuning a choke to deliver X% at a certain yardage, et. with a particular load. You might want to just do a search on those names on trapshooters.com for some interesting reading.

Briley Corp has a good rep, but I find it to be a bit large and impersonal for my tastes. I know of too many cases where the "paint job was fantastic, but the wrong color was used."

Mike --

Thanks for the additional information. I very much appreciate your help. I knew of Stan Baker -- but, not the others.

I will see where all this information leads.

As a point of discussion, Without the rejoining of the barrels, I cannot see how the barrel performance can be usefully altered, except by choke modification. So, this may narrow the field in light of your descriptions of the competencies.

I agree, Briley does seem to have grown enormously, since I first dealt with them. On the other hand I have never experienced a single problem in any of my interactions. I have carefully measured the Briley choke dimensions and surface finishes. I have been very much impressesed with their machining capabilities and quality control. Briley is prepared to pattern the gun ($125) to define the requirements for the choke alterations .... or I can supply representative patterns / information.

Thanks again.

Best Regards,

Don