Rebarreling and Home-Shop Machining

            Photo 1 shows the finish on the muzzle of the .300 Winchester Short Magnum (WSM) project’s stainless steel Hart barrel. I used the M42 Cobalt High Speed Steel bit in photo two to achieve this finish with flood coolant. No sanding was done on the muzzle. I get the same good finish with spray on lubricant using this bit. The bit has a tiny radius stoned on by hand. A similar bit in High Speed Steel might work as well. The bit is actually a Brownell’s threading bit which did not work well on threads on my lathe. I got some chatter. I stoned the top flat to remove the back rake and stoned on the small radius by hand. I used 120 Revolutions per minute and 1/3 inch per minute feed rate.

            I have a theory that the reason this bit produces a better finish on steel than a lot of others that I have tried is simply the increase in surface pressure on the small tip. This causes the built up edge that forms on the bit to be less of a problem. The lathe simply does not have the rigidity to obtain a good finish with a large radius bit of the kind that is used on a bigger lathe when cutting steel. A sharp bit will tend to produce a good finish for a few inches and then the built up edge starts messing up the finish. The bolt recess has a similar good finish using a brazed on carbide tipped tool and coolant. This 1/4 inch boring bit from my boring head also has a small radius. The interior finish on the chamber was excellent as well. In this case the reamer provides its own rigidity by having a blade on the opposite side also engaged in the cut. The flood coolant probably helps a lot here though. The chamber polished up quickly with a homemade flap sander using only 1500 grit paper. I was a bit worried about using the stainless barrel on this Shoptask lathe, but all the surfaces cut very similar to the Chrome Moly Barrels. I did need more belt tension on the final pulley to drive the large WSM reamer which is the same OD as a shortened Remington Ultra Mag.

            I still don’t get an excellent finish on my threads using a single point tool. I think this is from lack of rigidity and the necessity of the bit to cut the entire thread on the final passes. I do use a thread form where an excellent finish here is not so important. Some very light passes near the end does help some.

Bead Blast Finish on Stainless Steel

            A popular finish on stainless steel is a satin grey bead blast finish. I discussed this below and described the equipment that I used. I had good luck with this Hart Barrel. See Photo 3.

            First I band filed any imperfections off the barrel blank with a 120 grit belt. I then made the following adjustments to the Bead blaster. The regulator was set at 110 psi. I am using 80 grit beads from Harbor Freight Tools. I adjusted the sand feed at the bottom slightly past 45 degrees open. I cut off a bit of air using the air throttling valve behind the beadblaster so that I could open the last valve at my hand more fully. I got a good light continuous stream that was easy to control. I did not use much sand this time as my blaster was set pretty well from my practice run. I took the barrel in to really good light once for an inspection and repeated the sand blasting at two small areas. I had the barrel rotating. The finish was very even when I was through.

            Photo 4 and 5 show the barreled action in an HS Precision stock which I inletted with a method described on the CD that comes with precision Rebarreling.

Trigger Work on a Remington 700

            If you go lighter than 2 lbs on a Remington Factory trigger, the trigger may fail to return forward on occasion. This creates an unsafe condition. The lower front screw on the factory trigger can adjust trigger tension to some degree. The problem is that the little spring which surrounds the stub on the end of this screw is so stiff that adjustment is not really possible, its either heavy or unsafe. Holland sells a reduced power trigger spring for this trigger as well as an increased power bolt stop spring. These are available and correctly identified in Brownell’s Catalog. If you would like to make a reduced power trigger return spring, this is what I do to mine. I take the screw out and remove the spring. I put the spring on a small jewelers screw driver with my finger on theend of the blade. I sand the spring which rapidly rotates with the large drum sander from the Dremel until half the springs diameter is removed. You end up with a half round wire spring. When reinstalled, you can adjust trigger tension much more precisely. If you like to store your rifles for long periods and then use them without much attention, leave the tension at 2 lbs or more. If your rifle gets routine use and action cleaning, you can experiment a little.

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