I’ve been reading your responses for a couple of years now and you definitely have command of shotgun knowledge. That’s why I ask you this question about O/U barrel convergence. After much testing by several methods I have determined that my top barrel shoots 4 to 6 inches high at 40 yards (which is about 65/35 in relation to POA depending on which of my reloads I shoot).The bottom barrel is near 50/50 POI @ POA. Now, do you think that porting only the top barrel will lower the its POI enough to bring both barrels to the same POI?
Thanks for your thoughts,
I don’t think that porting will influence the convergence at all. Porting only works, if it works at all, after the shot has left the barrel and the gasses can vent.
A barrel misconvergence of 4~6″ at 40 yards is, surprisingly, considered within normal production standards by some makers. One company I contacted felt that up to 8″ misconvergence at 40 yards was acceptable.
You can get it easily fixed if your gun has fixed chokes. Just send it to Briley and they will relieve the top choke at the bottom or the bottom barrel choke at the top to bring barrels together. That will cost you a little choke constriction. If you have screw chokes, Briley might be able to supply elliptical chokes to correct it. Or you can just forget about it and shoot the gun. 4″ at 40 yards really isn’t that much in the scheme of things. Or you can sell it. Those are pretty much your choices as I see it. But ask around. Others may have different experience with the issue.
Don’t think that you are the only one with this problem. A surprising number of O/Us and SxSs misconverge. It’s just that most owners don’t test for this, so they never know. Here’s a really good bit of Technoidal advice: If you have a gun that you shoot well, DON’T test it for convergence of point of impact. It’s like going to the doctor when you feel good. You can only break even or lose. You can’t win.
Shotgun Report’s Technoid