The Hobby Gunsmith

The Scattergun-

Bounty Hunter II rebuild Part Three

Last month we replaced the Ruger Vaquero mainsprings with the original Baikal springs to see if that would correct the reliability problem with this gun.  We also changed the shape of the cocking cams in an effort to help the Bounty Hunter II remain open far enough to allow competitive loading.

   Our range testing showed the reliability issues had been corrected and it was time to test the gun in competition.  The results of the first actual competition field tests were somewhat mixed.

   The gun fired very reliably on all shots during a match in Manteca, CA, but there were problems with the gun not remaining open far enough to quickly load in competition.  This caused a lot of loading problems and was discouraging.  The problem was that the gun would almost stay open, but not quite.

   I thought about the problem and gave it another try in Jamestown, CA.  I also remembered that gunsmith Coyote Cap had given advice to another person to open the action by pushing the release lever to the right, but then to hold the release lever to the left to hold it open.  That did the trick and the gun became much easier to reload.

   This means the proper sequence for shooting the gun with the stock springs is to push the release lever to the right to release the action.  Break the gun open smartly to overcome the tension of the stock mainsprings and cock the gun.  Push the release lever to the left to hold the gun open while throwing the shells over my shoulder.  Continue holding the lever to the left while reloading with the left hand, and then releasing the lever and flip the gun closed for shooting.

   During the last days before writing this article, I was told that the Colt M-1911 mainsprings might also work to lighten the cocking forces and that the Colt mainspring is a smaller diameter than the original Baikal springs so the binding should not be much of a problem.  We will try to obtain one of these springs for testing next month.

   It is time to turn our attention to the forcing cones in the front of the chambers of the Baikal.  The purpose of the forcing cone is to make a transition from the chamber diameter to that of the bore.

   As the hull is forced open by the shot payload moving forward against the crimp, the crimp opens and is pushed against the walls of the chamber.  The payload of shot, which is usually contained by the shot cup, is flattened and pressed out against the walls of the chamber under the pressure of the explosion a the rear of the payload.

   As the payload reaches the chamber walls, it deforms and expands to the walls of the chamber and then moves into the forcing cone where it is squeezed down to the size of the barrel.

   The general conscious is that short forcing cones are needed to accommodate blackpowder loads that use fiber cushion wads.  The short forcing cone helps to prevent cushion wads and cards from turning in the forcing cone and interfering with the payload.

Longer forcing cones smooth the transition into the barrel and it is argued that smoothing this transition reduces chamber pressures and reduces the felt recoil.  A longer forcing cone is also supposed to reduce the disturbances to the payload of shot and help tighten the shot pattern.

   We decided to lengthen the forcing cones of our project gun so we purchased a forcing cone lengthening reamer from Brownells.  Unfortunately, we missed a step and ran into some problems that we will explain so our readers will know that things do not always go smoothly at The Hobby Gunsmith

   The first thing to do is to determine if your shotgun has chrome lined barrels or if they are steel.  The reason is that normal forcing cone reamers cannot handle the harder chrome barrels and will quickly become dull.  If you have chrome lined barrels, as we do, then you will have to purchase the special carbide reamer for those forcing cones.  The catalog states that the reamer for chrome lined barrels should not be used on standard steel barrels.

Figure 1.

   Thinking that the Baikal had standard steel barrels, we examined the forcing cone as can be seen in figure 2.  Note the sharply defined dark ring that can be seen between the lighter reflection of the chamber and the much brighter reflection of the barrel. 

Figure 2.

   We went to work and found it nearly impossible to cut through the steel and I wondered what I was doing wrong.  A quick note to Coyote Cap resulted in advice that the Baikal  has chrome lined barrels and that I had dulled my reamer.  He also told me  how to sharpen the reamer, which was helpful.

   For the sake of illustrating this process in time to be published, I pulled out an Interstate Arms Model 1887, which is their double barrel coach gun with external hammers.  This will probably be the next shotgun project for The Hobby Gunsmith.

Figure 3.

   Figure 3 shows the forcing cone in the Interstate (Formerly Norinco) chamber.   The forcing cone looks like a curb in the photo, but it is really about a half an inch in length.

Figure 4.

  I took the reamer and painted it with cutting fluid before inserting it down into the chamber.  As it began to wedge itself into the chamber, I began turning it clockwise to begin the cut.  The reamer will just about pull itself down into the cone at the proper force to make the cut, but I did give it a little downward pressure. 

   If the downward force is too great the reamer will start to bind and downward pressure should be reduced.   If it is not cutting enough, it will dull the cutting edge.  The proper tension should produce a scraping or dragging sound during the cut, but not any chatter. 

   Turn the reamer twice and then remove it by continuing to turn clockwise while removing downward pressure and then lifting slightly.  Do not reverse the reamer as that will dull it.

 

Figure 5.

   Figure 5 shows the reamer after being removed from the initial cut and before being cleaned.  Note the cutting edges are coated with chips of material removed from the barrel in front of the original forcing cone.  If you find yourself pushing very hard to get a bite, or if the cutting chips are very fine, you may be attempting to cut a chrome lined barrel with a reamer intended for softer steel.

Figure 6.

   Figure 6 shows a little of the old forcing cone with the new and longer taper behind it.  You must click on the thumbnail to see the details of the change.  The old forcing cone has diminished greatly since figure 3.  The reamer is taking a longer bite into the metal and it is time to check the forcing cone progress more often to prevent cutting too far.  The objective is to just barely remove the old forcing cone.

Figure 7.

   Figure 7 shows the view of the forcing cone when the original cone has been cut away and the newer and longer cone is now fully visible.  The cutting process starts by changing the taper in front of the original cone and the original cone will appear to vanish as the new and more gradual taper replaces the older cone.

   We polished the chamber and the new forcing cone area using a Flex-Hone.  The Flex-Hone looks like a series of abrasive balls on the end of stiff wires.  The tool should be used with the matching oil for the best results and the longest life of the tool.

Figure 8

   The Flex-Hone is chucked into an electric drill, dipped into the honing oil, and then moved in and out of the chamber while the hone spins.  The tool creates a slurry that quickly cuts the chamber and leaves the surface a little rough.

Figure 9.

  The ideal solution would be to polish the forcing cone with a special tapered Flex-Hone tool designed to match the contour of the new forcing cone.  This may be done in the future as our budget allows. 

   In the meantime, we now have a long tapered forcing cone on one chamber of our test shotgun and we will be testing the gun to see if there is any reduction in felt recoil on that chamber.  We will report more back next month on the success of this modification.