Regulating Barels on Double Rifles

[dagunner]

I am planing on building a doubl rifle on a boxlock action that will be chambered for either a 470NE or 577NE. I have concernes about regulating the barels. I am not sure how this would be done and keeping the two barels at the same angle to the breach face. In other words, how do I keep the centerline between the two barels perpendicular to the face of the breach when regulating the barels?
I hope that this question makes sense as stated because my comunication skills are sometimes lacking. Thanks for any help and advice.

 

[Jim K]

Wow! Quite a question. First, regulating the barrels is one of the most difficult jobs involved in building double guns, especially double rifles, and is one of the main reasons there are few makers and the prices are very high.

You first fasten the barrels at the breech, getting them horizontal in the process. You can do this by dovetailing one into the other, or by setting both into a separately made breech, which will also contain the locking lugs. Welding or soldering the barrels together at the breech can be done on shotguns, but a rifle requires a stronger system. Once the gun is together and the barrels in place, you start firing. Using wedges or clamps, you bend the barrels the way you want them to go. Once both barrels shoot to the same place, you solder in permanent spacers, install the ribs and the job is done. (Sounds easy, doesn't it?)

With a double rifle, you determine the distance to "zero" the rifle, that is the point at which the bullet trajectories will cross. (The bores are not parallel, they converge, so the bullet paths cross at some point, then diverge.) I think that is usually about 20 yards, but can check some books if necessary. The idea is to have the gun shoot both barrels to the point at which the hunter will expect to encounter dangerous game.

Jim

 

[Jim Watson]

It is said to be all in here:
http://www.brownells.com/aspx/ns/st...tle=BUILDING+DOUBLE+RIFLES+ON+SHOTGUN+ACTIONS

BUILDING DOUBLE RIFLES ON SHOTGUN ACTIONS
W. Ellis Brown. 187 pages. 8½" x 11". Hardcover. Over 250 photographs and illustrations. Well illustrated, easy-to-follow step-by-step instructions guide you through the process of building a custom double rifle on a shotgun action and avoid the expense of a British double rifle. From defining the scope of the project to fitting the barrel to the action, proofing, regulating and finishing, Brown shows you the closely guarded steps of building double rifles, which are not beyond the skills of a good gunsmith.

There is a forum on double gun building at:
http://www.nitroexpress.com/
and some related information at
http://forums.accuratereloading.com/eve

And, Jim, you don't HAVE to regulate the barrels to cross shots at some arbitrary distance, surely not as close as 20 yards. It is, from what I have read at nitroexpress.com, quite feasible to make one shoot parallel. The tubes are not parallel, but they can be regulated to make the points of impact so. If the muzzles are an inch apart, then the barrel groups will center an inch apart as far as you can hold the usual iron sights.

 

[BigG]

As Mr. Keenan noted, the bbls are not parallel but actually converge at a certain distance. Another point to note: Doubles only shoot well with one load, so you use the standard load and set the convergence with that.

The only exception noted is the 375 H&H double shoots all three bullet weights 235 - 270 - 300 gr into the same group.