The Belt Mountain-Bowen #5 Base Pin


A short treatise on the meaning of:(warning-requires fitting)


2002. Last year, Dad and I rebuilt a Flattop Ruger .44 magnum into a .45 Colt Packin' Pistol. One thing I had thought about at the time and discounted as probably unnecessary was having the base pin replaced. I figured that, since the primary load for the gun was going to be Winchester factory, the pin should stay put. With factory loads, it did. Unfortunately, any hand load even beginning to approach factory levels made the pin jump after two or three rounds at the most. I put off replacing the pin until, just recently, it started coming lose after ten or twelve rounds of factory ammo. Dad and I were over at the J-T Ranch recently and I mentioned to Jim that I was going to get a Belt Mountain base pin to solve the problem. Well, Jim hauled me into his shop and pulled out a little manila envelope with one of the new #5 base pins with Hamilton Bowen's screw-stop. It seems Kelye had sent him one to see what he thought of it. Jim offered it to me in exchange for an article about fitting it up. 


 Dad and I found the time to fit the pin and screw one Saturday afternoon and by the time we were done, we'd spent a bit less than one hour getting the job done. I feel we were lucky as the pin itself fit the gun perfectly and no fitting to the receiver was needed.

The following illustrated steps should give you a good basic idea of how to do the job. As always, you can click on any of the images to look at a larger view

guninvise.JPG (170309 bytes)   One. Lock up the gun in a medium vise. Use leather vise pads to prevent marring of the finish. Remove the screw and insert the pin into the receiver.

markingdrillstart.JPG (178181 bytes) Two, Using a hardened tool steel center punch (centered through the screw hole) and light hammer, lightly whack a index mark on the barrel.

drillstartmark.JPG (167272 bytes) Jim told me that Kelye is developing some kind of  jig to eliminate this step The positioning of the index mark is the most critical part of the job. If the mark is off, you will drill the hole off. This is not good, this is BAD.

handdrillstarthole.JPG (181144 bytes) Three. The tip of the screw measures .125" Dad decided to use a worn .140" bit to drill the hole. Using a hand vise, begin to drill the hole until the bevel of the working end of the bit has made a complete diameter cut.

drillpresshole.JPG (210985 bytes) Four, Lock gun into a drill press vise. Check for level of both long and cross axis. Start up your drill press and SLOWLY drill a hole approx. .05" deep. You really want a hole just deep enough to have visible vertical sides. 

filescrewend.JPG (212814 bytes) Five. Hand file the end of the screw down to fit the depth of the hole. This really takes at least three steps as you should make small cuts with the file. Put every thing back together, re-eyeball the fit and cut again until the head of the screw fits down through the pin as far as it does with the pin out of the gun. The tip of the screw should bottom out down the hole in the barrel. This does not have to be exact but, you do want as much of the side of the tip to fit the side of the hole as possible.

finished.jpg (154331 bytes) Six, Put your gun back together and enjoy!


Thank you for your kind attention.