TargetTalk

The other day at team practice a 15-year-old using one of my Kimber 82G Position Rifle builds commented that her rifle was “shooting all over the place”. Having heard that once or twice before as a coach ;), after a quick once-over for obvious faults, I promised to check the rifle after practice, as she was having a bad day. Well, sure enough, I tested it on the bench and it wasn’t performing anywhere near to the level it was when I put it into service nearly two years ago.



So I allocated a couple-three shop hours to putting the rifle back into tune. As this wide-ringed (less than optimally stable), plantation-walnut stock spent 25 years in an Alabama warehouse before spending a couple years here in a dramatically different climate, bedding is the first suspect. I do pillar bedding in two stages, the first a simple glass-bedding using custom bedding studs made for the purpose in lieu of the action screws, and in the second stage install the pillars. Bedding studs are important, as they are sufficiently long to sight “centered-and-plumb”, and eliminate the possibility of getting epoxy into the action screw holes. I also use a combination of modeling clay, electrical tape and common paste wax as release agents. The recoil lug is conventionally- taped on its front three sides before setting in epoxy for clearance, although in a rifle without significant recoil, this is of relatively minor importance.



Because we have unusual and highly-variable weather compared to most of the country, I prefer to make my own bedding compound from a low-shrink 5:1 epoxy thickened to the correct consistency using high-adhesive cabosil with powdered stainless steel mixed in. I can control its’ consistency and how fast it kicks off regardless of temperature and humidity. It’s also considerably less expensive, and I never have to fudge with not having enough of it in the middle of a job.



During both stages of bedding, I’m especially careful to keep the bedding studs dead center in their holes (and modifying the holes if required). Barreled-action harmonics are identical to piano strings. Perfect consistency requires a solid, unchanging sound board, and that requires mounting where under no circumstances are the action screws less than equally-torqued, dead plumb or touch the side of their holes.



To insure the holes remain factory-centered, I carefully ream them out in steps on the drill press until I can use my Brownell’s piloted pillar bedding bit. To their shame, Brownell’s makes a great bit but won’t even consider offering interchangeable pilots for folks who work on rifles other than Remington 700’s . (Don’t bother…I’ve already asked. ;)) I also prefer the purpose-built Brownell’s 3/8” bedding pillars to brass plumbing nipples where I have room to use them. They save shop hours.



I have another article in the works on updating an old, well-worn Annie club rifle to go back into service where I treat this in more detail, but again, the overriding principle during pillar installation is to keep the action screws plumb and centered.



One detail I overlooked in my hurry to put this rifle into service two years ago was the final crown cut. It’s counterbored, not beveled. And the counterbore is rough with tooling marks….a perfect crud magnet, almost impossible to keep clean.



So I select my tightest pilot and my thickest cutting oil, and with a progressively lighter hand carefully recut the crown with the barrel fixed in the vise on a downward slope so there is no way a chip can get into the lands, causing a scratch. I no longer attempt lapping fresh-cut crowns using abrasives, as the process is less precise than the cutter and can be counterproductive. Instead, I concentrate on a progressively finer cut graduating down to almost nothing followed by firelapping the delivery end using fifty to a hundred rounds of practice ammo.



I purposely didn’t cut a full bevel, but just enough to remove the tool marks from the delivery end and ease cleaning. I’ll see how it performs before going further.



Testing on the bench on the International 50 Meter Target against a .4-inch 10-Ring demonstrates the rifle is back to the point where it can clean the target. But the action remains sensitive to torque values on the action screws. The front screw likes 5 Newton Meters, but the action performs best with the rear screw just drawn in snug. As the rifle is now adequate for our purpose, I'll watch it for a while before tweaking anything further. I suspect the torque difference is because I have the recoil lug bedded a tad high, and I'm thinking about investing in a new Manson Precision crown cutter so I can redo several rifles that I believe would benefit.

The accuracy of the complaint notwithstanding, commenting on the gunsmith’s product works both ways. When I hand this rifle back to her this week along with the test target, it’ll be with a hundred rounds of expensive test ammunition and the admonition that, “There are no compromises today…I expect your full focus and delivery of your best performance, ever.” ;)

Bob Smalser

http://www.wkfinetools.com/contrib/bSma ... -index.asp
http://www.woodcentral.com/cgi-bin/articles.pl#smalser

Thanks for that great article!

If you don't mind me asking, how do you decide how much of the crown to cut?
Do you usually cut it by hand? Even with larger calibers?
Could you please elaborate a bit more on this subject. I would really appreciate it.

Thanks again!
rmca

Normally I cut a full bevel, like on this saddle gun I restored after a mishap on horseback that mangled the front end.



But the only real reason for the full bevel is ease of cleaning. The only section that's important to be perfectly plumb and free of scratches, worn spots and tool marks are the first few thousandths where the bullet exits the bore. I didn't do the full bevel on the Kimber because I'm planning on getting one of these 11-degree target crown cutters, and the deeper the bevel the more work using one of those.

https://www.youtube.com/watch?v=-Xpzv1Spsnk

Got it!

Thanks a lot.

Not a bad group, but not an Olympic rifle either.
Nice write up, I like that lead hammer peeking in one of the pictures, teasing the EPA. Lol