The Hobby Gunsmith

The Scattergun-

Bounty Hunter II rebuild Part One

Many cowboy shooters have adopted the Russian made Baikal Bounty Hunter II double-barrel shotgun as their preferred match shotgun. This project will take a used and unreliable BH-II and restore it to one that both looks and shoots well.

   I purchased my BH-II last year from another Cowboy Action shooter who reported that it was reliable. This gun had been modified with Ruger Vaquero hammer springs and a few other modifications that have been posted on popular web sites.  This one had been modified in accordance with those directions before I purchased it, so I have never actually seen a new BH-II shotgun.

   This gun came with the action polished, the mainsprings replaced with Ruger Vaquero springs, the safeties removed, and the mainspring housings already polished.  I shot the gun for several months, but it would occasionally misfire on the left chamber. As the problem worsened, it reached the point where it was no longer serviceable so I took it apart to look for the cause and I found some interesting things.

   Let's begin by saying that the modifications done on the gun were fine and I have nothing but praise for work that had been done as it was first rate.  I did make some changes that shed light on potential problems in those modifications and I have done some experimenting to see how they can be further improved.

   Let's begin with an explanation of how the Bounty Hunter shotgun internal parts work so we can fully understand the benefits and pitfalls of the gun.



   The photo above is a top view that illustrates the various parts so we can have a visual aid for the discussion. The photo shows the receiver in the middle, the hammers on each side at the top, the cocking levers and mainsprings next to the receiver, the little cocking cams, and on the right is a special tool I made to polish the mainspring channel.

To begin with, the BH-II looks like any other shotgun with internal hammers. After firing the gun, the release lever on the top of the tang is thumbed to the right until it releases the barrels to swing down and into the open position.

   As the barrels move down, the cocking cams under the barrels engage the cocking pushrods that are inside each mainspring. These pushrods run from the front of the water table and back to engage a hole in the hammers.

   As the barrels begin their downward travel, they will drop freely until the cocking cams engage the cocking pushrods. If they do not, there is probably some binding that needs to be polished.

As the barrels come down, the cams push on the cocking pushrods and the hammers are pushed to the rear against the force of the mainsprings that are coil springs wrapped around the cocking pushrods.


   As the barrels approach the bottom of their travel, we can hear the hammer sears engage the trigger with a gentle click-click and the extractor moves rearward to push out the empty hulls. This is where problems may begin.

   The gun may not be open enough to cleanly pull the empty hulls and the barrels will have to be pushed down further against the already compressed mainsprings in order to open the chambers that last half-inch needed for the hulls to clear the standing breech.

   This indicates a timing problem that allows the hammer sears to engage before the action is fully opened.  Because of this, the barrels must be forced open against the hammer springs while they are under the most tension.

   The opposite problem can also be found as I have heard of some BH-IIs that will reach the bottom of the barrel travel before the sears engage, which leaves one or more hammers not cocked.  If a hammer is not cocked, the gun must still be held against the force of the spring.

   Assuming the gun is then loaded and the barrels closed, the cocking cams are allowed to relax in their hinges and the mainsprings are retained by the sear. The mainsprings are compressed over the cocking pushrods, which now act as hammer pull-rods. The end of the mainspring pushrods are engaged in a sloppy hole in the hammer and are now trying to pull the hammers forward toward the firing pin hole in the standing breech. The hammers are retained by the trigger sear.

   As the gun is brought to the shoulder, the shooter will acquire the target and pull the front trigger, which fires the right barrel. As the sear disengages, the cocked mainspring will pull the hammer forward until just before firing the gun. Inertia will push the hammer's firing pin into the primer and fire the shell.

   Remember the slop I mentioned? That's the play in the hammer hole where the cocking pushrod engages the hammer. There is a little spring in the hammer that controls the play and tries to prevent the hammer from striking the primer. The spring is too weak to actually stop the hammer, but it can slow the hammer a little. After the primer is fired, the little spring removes the slop by pulling the hammer back away from the primer and into rebound position.

 

  Those are  the highlights of how the BH-II works. With an understanding of the design of the gun, we move toward some experimentation to learn why the gun is randomly failing to fire.

   This BH-II was equipped with Ruger Vaquero revolver mainsprings, which lighten the cocking quite a bit. The previous owner had done a good job of polishing the spring guide channels to reduce friction between the spring and the guide channel.

   I examined the Ruger springs and found they are much lighter and have an outside diameter that is .010 larger than the original springs, but the inside diameter of the Ruger springs are a full .045 larger.

   This can create two problems in the BH-II shotgun. First, the slightly larger outside diameter of the Ruger springs can cause additional binding in the roughly milled spring guides of the BH-II. Second, the Ruger springs tend to deform or snake, when compressed over the pushrods. This allows sections of the springs to bind against the spring guides, create friction, and some randomness to the hammer movement.

   I tried to improve reliability by further polishing the inside of the mainspring guide channels with the help of a little tool I made. This was to reduce friction where I could feel the deformed mainspring binding against the inside of the polished channel.

   I greased up the springs with top quality pro-gold grease and tested it.  Neither barrel would fire, which told me I was close to the problem. I had either messed up the guides by polishing them again, or the grease was making the problem worse.  By changing the symptoms, it suggests I was in the area of the problem.

   I took the gun apart and lubed the springs with a very light oil and it returned to normal, but the left chamber was still unreliable. This suggests marginal springs and a variable amount of friction caused by changes in the lubrication and from the deformation of the hammer spring.

   I let the gun sit for a few weeks before taking it out for field testing.  The gun misfired on the left chamber approximately thirty percent of the time while the right chamber only misfired once in twenty-five test rounds.

   Drop in next month as I begin making modifications to the gun.  I will be replacing the Vaquero springs with the original springs, will work on reducing the spring tension of the original springs, and will adjust the timing of the cocking cams.