Rebarreling and Home-Shop Machining

            If you study a magazine fed Remington 700 action before the shot you find that the rear of the bolt is held up by the trigger parts and by the magazine follower. I have always thought that on the Remington action, it might be helpful to hold the rear of the bolt upward by some mechanism in those cases where the bolt is not sleeved. (By sleeving I mean precision boring or lapping the bolt bore and then removing the bolt handle and turning the bolt and installing a larger diameter sleeve to precisely fit the bolt bore.) I found the mechanism, that I envisioned, in the Crawford Engineering Part. It does two things. It puts the bolt in a more reproducible position before each shot increasing precision. If both lugs were lapped, while the rifle is cocked holding this upwards position, as is my habit, you would get more even bearing on the bolt lugs. A second benefit according to Crawford Engineering is a more reproducible trigger pull allowing better adjustment of the trigger. I decided to add the Crawford Engineering Stabilizer Bolt Shroud that is available at Midway to my Winchester Short Magnum project rifle which I discussed first in a topic in this Journal. The base for this project is a new Remington 700 in .300 Winchester Magnum. This pre stainless steel model rifle has a bolt safety lock that uses a key to disable the action. The new shroud does not.

            The way this new bolt shroud works is that a couple of nylon tipped screws bear on the action rails at the bottom of the bolt and hold the shroud upward. The play is set to .004 inch with a feeler gauge under one of the green tipped screws. The screws are secured with Loctite.

            Note that another new product , Bolt Body Shim is available to sleeve the bolt. It is a split cylindrical shim set that is epoxied to the bolt in front and the back of the bolt. The shims are hidden when the bolt is in the firing position. I like this about as much as a thin glass bed on an aluminum bedding block. In a couple of years the epoxy will probably weaken and crack. I would rather not use either method on a hunting rifle although for a target rifle epoxy is commonly used.

Results

            Although the Crawford Engineering Bolt Shroud had potential it did not work that well on my particular Win Mag action.The problem I had is that when it was adjusted as recommended with the rifle cocked and the bolt down, it became tighter with the bolt handle up and so the bolt became difficult to open. I suspect that the internal threads on the Remington Bolt are not quite in the center of the bolt. This caused the problem on this particular action. I will try it on another action later and see if I get lucky.

            I tried the new Crawford Engineering bolt shroud on my 30/06 27 inch Douglas Barreled Remington 700 Rifle. This rifle has an old action. The Shroud worked as advertized on this older action due to a better centered thread in the bolt of the rifle. (This could be checked with feeler gauges under the shroud before a new Shroud is purchased) The Crawford Bolt Shroud maintained its adjustment as I opened the bolt handle. The bolt opened and closed easy without play at the rear. The trigger felt good and consistent. The rear of the bolt does not drop now when the trigger is pulled. The results are shown in photo 1 which was a .302 inch group for the three shots including the cold barrel shot. I was pleased. This is about .1 better than before this change, but further testing would be needed to confirm this result. It certainly did not hurt things. Photo 8 shows the finished job.

Straightening the Internal Threads on the Bolt

            I decided to try some corrective action on my Win Mag action’s bolt tosee if I could make the Crawford Engineering Shroud work on it. First, I chucked the dissasembled bolt in my true running three jaw chuck. I inserted a standard shroud with a tight fitting mandrel in the rear hole of the shroud. When running the lathe the mandrel had very visible (huge) runout. The shroud was cocked at an angle in the threads that were crooked in the bolt. I used the lathe and a ½ inch by 13 TPI tap to straighten the thread in the bolt. I started the tap a couple of threads by hand then chucked the tap hard in my truest running chuck which is held in the tailstock. I turned the lathe by hand which advanced the tap and dragged the tailstock forward. The tap made a slight cut on the innner most part of the bolt. The shroud now turned with no runout. It seemed to be still a good fit; not too loose. A check on the action showed an unchanged clearance under the shroud as I opened the bolt. I’ll buy an new Crawford Engineering shroud and give it another chance. I also considered home machining a close fitting shroud, but may not need to do this.

Homemade Firing Pin Assembly Tool

            I made the tool, shown in photo 3 - 7 to reassemble the firing pin. These are also available commercially. I started with ½ inch aluminum stock which was bandsawed to make two parts 1.5 inches wide by 3.5 inches long. The large center hole in one piece is 3/4 inch with a 1 inch counterbore 3/8 inch deep. The counterbore was made with a standard 1 inch twist drill. I filed a slot to clear the cocking piece with a 3/16 inch round chainsaw file (these files have no taper). I used 1\4 inch x 5 inch x 20 TPI bolts which I had on hand. 6 inch bolts might be better. The other two holes in this piece are 1/4 inch with a deep 3/4 inch counterbore on the opposite side to make the 5 inch bolts start easy by hand.

            The second piece has a 3\16 center hole to clear the firing pin. The other two holes are drilled with a .201 inch #7 drill and tapped for 1/4 x 20 threads per inch. All the holes are one inch apart. Worked great.

Cautions

The firing pin spring is fairly strong. I imagine that if you disassemble the unit and screw up just right it could drive the firing pin deep into your body, so be careful and keep your torso to the side of the assembly.

Assembly

            See photo 6. Clamp firing pin in the vise between lead padded jaws. Push the shroud and cocking piece on by hand. Start screws by hand. Tighten screws until cocking piece securing pin hole is exposed. Remove from vise and pound in pin with ½ inch support block under hole. Note the extra notch at the top of the outer plate to clear the safety lock on the bolt shroud on late model Remington rifles.

Cool Tool, Right Angle Socket Drive

            Photo 8 shows an interesting 3/8 inch drive right angle socket drive from Mac tools that belongs to my nephew who is a Ford Technician (Many thanks for his help on the Ford Focus Cold Air induction project) The rods that connect the two parts are solid and move in and out of the end pieces as the socket rotates. Really ingenious tool. I tested it. It works pretty well without losing a lot of torque.

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