doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com FAIR Iside response to improper regulation of brls

Personally, I do not believe that straight edge bit is totally reliable. Many doubles, particularly relatively lightweight ones have their OD's increased in the choke area so they are a bit "Swamped". Also even if proved to be perfectly straight there is still the matter of did they get set to the absolutely correct convergence, which of course can vary a bit according to load used.

If the choke threads in the barrel are off, someone like Mike Orlen or Briley could probably rebore concentrically and install a permanent choke sleeve in that barrel. Not ideal, but a fix.

I'd start by reversing the two current tubes, left to right.

It is usually not that hard to move the pattern 8" at 40 yds, but moving it 8" at 16 yds will be a challenge. Since it looks like you are stuck with the gun, I would sure give it a try. I have successfully moved the POI on several sxs guns, so I know it can be done. I had Brileys make eccentric chokes for one gun, and they definitely moved the pattern, but they moved it way too far. A guy on another forum told me how to file it to move the pattern, and I would rather do that than to buy eccentric chokes.

Filing the choke utilizes the same principle as eccentric chokes. The idea is that a change at the very end of the barrel can cause the wad to go in a slightly different direction. It's the same idea as damage to the muzzle of a rifle can change where it shoots. In a shotgun, this will only work if you use shells with a plastic wad, but most of us do that anyway.

Fwiw, here is an explanation of how to file a choke and move the POI:

Put your barrels in a vice and face the muzzle end. Your left barrel is shooting to the left, so you want to move the POI to the right. You do that by filing the inside of the barrel right at the muzzle.

Imagine the image of a clock placed over the muzzle. The left barrel is shooting to 3 o'clock now, so you want to file it at 9 o'clock. I use a round chainsaw file, and start by making 4 strokes at 9 o'clock. Hold the file at a 45 degree angle and you will be removing metal from only the inside edge of the barrel. Next, make 3 strokes at 10 o'clock and 3 at 8 o'clock. Then make 2 strokes at 11 and 7, and feather it to 12 and 6.

What you want to do is to create a chamfer that is deepest at the direction you want the pattern to go, which is 9 o'clock in this case, and then slopes to no chamfer at 12 and 6. After making the initial cuts, fire a test shot and see if the pattern moved. If it didn't move far enough, file again. Keep filing and keep shooting until it centers.

You will probably have to get the choke to a knife edge at 9 to move the pattern as much as you need, and even that may not be enough. It's good that your gun uses choke tubes. If you don't want to risk one of the tubes that came with the gun, you can buy a tube for about $20 and that will be all you are risking. This procedure will degrade the pattern to some extent. If you want modified performance, start with a full choke tube.

Good luck with it.

I've done what Coosa suggested and it worked. It is however pretty noticeable if you look in the muzzle...Geo

Thanks for the tip coosa.

Thank you Stan. I hope your .410 is perfect. 16" at 32 yards is not slightly off! How can they sleep at night.

I had the IC and mod choke tubes in and had forgotten to take others. My shooting partners were waiting for me so I was a bit rushed and did not think of switching tubes. I just thought "darn, I should have brought the other tubes".

Before I do anything I will pattern it again with a different tubes.

Chuck, thanks. The sides are straight so it seems it is either the threads are off center or (I hope) something is wrong with the choke tube.

It would seem to me that bad press costs more than standing behind your quality control and fixing the problem. I guess they don't think so. think about that when you buy.

I agree. You should not have to fix a new gun. A used one I can understand. You pay less and in many cases you take your chances.

It's pretty reliable if you check the other barrel and it is straight. If it is swamped, then of course the other should be, too.



Milt, Just from personal experience, be diligent to hold the gun with the same amount of "grip" when you shoot each barrel. Do everything exactly the same. Guns are much more susceptible to how we grip them, in where they print, than many realize. I found this out with a lightweight double in the past. If I gripped it too tightly it cross fired. If I gripped it normally, it was perfectly regulated. So, if I had gripped it tightly with one barrel and looser with the other barrel, I would have gotten results similar to yours.

I believe that the lighter the gun the more susceptible it is to this variation in grip. Sometimes we get "jacked up" when patterning, and try to grip it too tightly in order to "aim" it closer.

Good luck, SRH

Stan'
Note that I said it was "Not Totally Reliable". It is not an absolute guarantee that if the barrel is straight it will hit the right place. I believe your illustration of changing the grip bears that out. You did not change the straightness of the barrels as you changed the grip, only the manner in which it recoiled. Likewise, the barrels can be perfectly straight but if the convergence is off a bit the barrels will not shoot to the same point of impact. Also, we have no guarantee the bores & the OD are absolutely concentric, it's where the bores point that is the important point.