The Belt Mountain-Bowen #5 Base Pin
as sold HERE
A short treatise on the meaning of: (warning-requires fitting)
Last year I had Jim Stroh of Alpha Precision rebuild a Flattop Ruger .44 magnum into a .45 Colt Packin' Pistol. You can read about that HERE. 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 recently doing some handload testing and I mentioned to Jim that I was going to get a Belt Mountain base pin to solve the problem. Well, Jim hauls me into his shop and pulls 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
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.
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.
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.
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.
Thank you for your kind attention.