T
toolmakr
Guest
I'm new on this forum, found a huge amount of info and interesting ideas. Not sure if this should go in general or gunsmith, but I'm hoping to get some help or more food for thought on curing a problem I have. A little background is needed, so please bear with me. The rifle is a new, unmodified, 12.5 pound single shot, bolt action .223 Savage Model 12 with a 26 inch, 1 in 9 twist, heavier barrel (1.040 near the nut, tapers to .812 dia. at the muzzle). It has a Nikon Monarch 6-24x 50mm dia. objective scope with fine cross-hairs mounted with Leupold rings and bases. Primary intended use is target shooting at 100 to 200 yards, although occasionally a varmint might find itself in front of it. Currently the varmints are pretty safe.
Depending on bullet weight, the gun groups completely differently. I know that is to be expected, but not to the amount I'm seeing. I haven't gotten the reloader dies yet, so my data are limited to factory ammo. 55 and 64 grain bullets from 3 different makers print in one general group and Hornady 75 gr. BTHP prints a better group centered several inches to the right at 100 yards. 10 shot group sizes are about 1.5" with the lighter bullets and 1.1" with the 75gr. A letter to the gunmaker went unanswered, so after collecting more data and wasting perfectly good gunpowder, I called. After informing me that different bullet weights shoot differently, they offered to have their gunsmiths check it out if I would strip off the scope and send it to them at my expense. In Savage's defense, the gun meets their 1.5 MOA guarantee, but I expected better even with factory ammo. Silly me.
But I still want better, so I've been experimenting with different shooting methods, bipods vs. sandbags, etc. I've made some minor gains, but not to the degree wanted, so it's time to try to improve the gun to see what it's really capable of. The barrel is fully floated, but the fit between the receiver and beautiful walnut stock is less than impressive, and I think that movement results in the large left / right group differences and is also partially responsible for the group sizes.
I know bedding the receiver in Devcon Plastic Steel epoxy would help. But, having been a toolmaker in a former life, I've been thinking about building a fairly large, say 1.5" square by 13" long aluminum bedding block. It would be machined for a line to line fit with the first 8" of barrel, clearance fit around the barrel nut, then line to line with the receiver back almost to the trigger assembly. It would go from the barrel centerline, down and have two wide, machined clamps over the barrel, and use the existing screws into the bottom of the receiver. There would be a slot for the recoil lug, flat on the back side and tapered on the front side for a wedge type clamp that would be pulled into place with a screw accessible from the bottom of the gun. Rough up the outside of this block and mill a loose pocket with a couple small "datum" surfaces and glue the block into the existing stock with the Devcon. Obviously all these line to line fits I mentioned would be a technical challenge, but it is possible.
The question is, in making the whole thing stiffer, will it now still "ring" but just at a higher frequency? Or is the vibration damping ability of the wood/bedding epoxy of more traditional bedding techniques the better solution? If I went with the more traditional bedding method, would anything be gained by running it 8 inches or so up the barrel? I would think the stock will eventually warp (doesn't all wood warp a little?) and try to take the barrel with it. Hence the idea for a far more complicated aluminum bedding block.
Sorry this took so long, I promise any future postings will be brief. Thanks in advance for all your comments. I look forward to hearing what you think of a crazy old toolmaker's idea.
Kevin
Depending on bullet weight, the gun groups completely differently. I know that is to be expected, but not to the amount I'm seeing. I haven't gotten the reloader dies yet, so my data are limited to factory ammo. 55 and 64 grain bullets from 3 different makers print in one general group and Hornady 75 gr. BTHP prints a better group centered several inches to the right at 100 yards. 10 shot group sizes are about 1.5" with the lighter bullets and 1.1" with the 75gr. A letter to the gunmaker went unanswered, so after collecting more data and wasting perfectly good gunpowder, I called. After informing me that different bullet weights shoot differently, they offered to have their gunsmiths check it out if I would strip off the scope and send it to them at my expense. In Savage's defense, the gun meets their 1.5 MOA guarantee, but I expected better even with factory ammo. Silly me.
But I still want better, so I've been experimenting with different shooting methods, bipods vs. sandbags, etc. I've made some minor gains, but not to the degree wanted, so it's time to try to improve the gun to see what it's really capable of. The barrel is fully floated, but the fit between the receiver and beautiful walnut stock is less than impressive, and I think that movement results in the large left / right group differences and is also partially responsible for the group sizes.
I know bedding the receiver in Devcon Plastic Steel epoxy would help. But, having been a toolmaker in a former life, I've been thinking about building a fairly large, say 1.5" square by 13" long aluminum bedding block. It would be machined for a line to line fit with the first 8" of barrel, clearance fit around the barrel nut, then line to line with the receiver back almost to the trigger assembly. It would go from the barrel centerline, down and have two wide, machined clamps over the barrel, and use the existing screws into the bottom of the receiver. There would be a slot for the recoil lug, flat on the back side and tapered on the front side for a wedge type clamp that would be pulled into place with a screw accessible from the bottom of the gun. Rough up the outside of this block and mill a loose pocket with a couple small "datum" surfaces and glue the block into the existing stock with the Devcon. Obviously all these line to line fits I mentioned would be a technical challenge, but it is possible.
The question is, in making the whole thing stiffer, will it now still "ring" but just at a higher frequency? Or is the vibration damping ability of the wood/bedding epoxy of more traditional bedding techniques the better solution? If I went with the more traditional bedding method, would anything be gained by running it 8 inches or so up the barrel? I would think the stock will eventually warp (doesn't all wood warp a little?) and try to take the barrel with it. Hence the idea for a far more complicated aluminum bedding block.
Sorry this took so long, I promise any future postings will be brief. Thanks in advance for all your comments. I look forward to hearing what you think of a crazy old toolmaker's idea.
Kevin
