Rejuvenating A Worn Throat
I’d hunted with the rifle for several days in New Zealand, often in pouring rain. A piece of electrical tape was kept over the muzzle to prevent raindrops from entering the barrel, and I left the rifle next to a heat source each night, with the bolt removed so the bore would dry out thoroughly. But some light pits still formed in the throat, right where the bullet of a round sat while hunting, probably from atmospheric moisture. A few rounds of FinalFinish bullets removed the shallow pits completely.
The Remington 700 223 has become Eileen's favorite rodent rifle over the years, and she's happy to see it shooting so well again.
Eventually it occurred to me to use lapping bullets to remove cracked (but not chunked) throat erosion in the barrels of some of my favorite varmint rifles. The first was a Remington 700 Classic in 221 Fireball that had been purchased used, then shot quite a bit on both ground squirrels and prairie dogs over two years here in Montana, as well as for an article on 221 handloads for The Varmint Hunter Magazine®. There’d been some light cracking in the throat when I bought the rifle, but by the end of the second season the cracks were deeper right in front of the throat, obviously moving toward the chunking stage. Accuracy also has noticeably declined, with more fliers.
The NECO Economy Abrasives Kit will rejuvenate a bunch of barrels.
So I got out my NECO Economy Abrasives Kit (NECO, 108 Ardmore, Benicia, CA 94510, 800-451-3650, www.neconos.com).This includes four different grits, ranging from 220 to 1,200. Bullets are treated by spreading a tiny amount of grit on a small steel plate, then rolling the bullet firmly across the grit with a small steel bar. I used Winchester 55-grain softpoints because they have a fairly long bearing surface, and there should be as much contact as possible between the gritted bullet and the bore. Since lapping bullets create more pressure than normal bullets, a starting load of Hodgdon Li’l Gun was selected for the job.
After 10 rounds with 220-grit, I looked at the throat through my Hawkeye. The surface of the cracked throat was smoothed considerably, but the deepest cracks were still very evident just in front of the chamber. Another five rounds of 220-grit made all the cracks disappear.
In conventional fire-lapping, the next step would be to shoot a few more rounds with 400-grit, then a few more with 800-grit and 1,200-grit. Instead, I treated the bore with Dyna Bore-Coat (formerly known as Ultra Bore-Coat), a solution of very fine ceramic particles in a quick-drying glue (Dyna-Coatings Group, 5000 E. 59th St., Kansas City, MO 64130, 816-444-1255, www.dynamicfinishes.com). The solution is slathered generously into a totally clean and dry bore, then after the glue dries for 30 minutes or so, five shots are fired to push and melt the ceramic into the surface of the rifle’s bore.
The ceramic coating is extremely resistant to jacket fouling. I’ve treated around a dozen rifles with DBC over the past three years, and even in the worst-fouling bores jacket fouling was reduced at least 75 percent. Some bores simply do not jacket foul anymore, one reason I never clean prairie dog rifles during a shoot these days. Oh, and one treatment lasts for the life of the barrel.
In my experience DBC is even more effective than using finer grits to fire-lap a bore, as well as being quicker and easier. Also, more fire-lapping tends to move the throat farther forward. A Dyna Bore-Coat kit treats at least half a dozen barrels, and even more in smaller bores such as the typical 17 to 6mms used for most varmint hunting. I applied it to the 221’s barrel, then shot five rounds and cleaned the bore. Since then the rifle has shot noticeably more accurately … in fact, even a little better than when I worked up its first loads, and the fliers have pretty much disappeared.
This was so heartening that the same routine also was applied to a laminated-stock, heavy-barreled Remington 223, the most accurate factory centerfire I’ve ever owned. It was purchased new from Capital Sports & Western Wear in Helena, Montana, and then tuned by free-floating the barrel, epoxy-bedding the action, touching up the barrel crown with a Brownells hand-tool, and shooting half-a-dozen NECO-treated fire-lapping bullets to smooth the tool marks left by the chamber reamer.
With match-grade 50-grain bullets and a load of 26.0 grains of Ramshot TAC, the rifle would average 0.25" for five-shot groups at 100 yards. Of course, that was with ammo put together with all the accuracy tricks, a big scope, and wind flags, but it also would shoot just about any factory load into half an inch.
It shot so well that it was used for an awful lot of prairie dog shooting for the next few years, though since I’m normally “testing” several rifles on any rodent shoot, it didn’t get shot as much as, say, Chub Eastman’s. Still, the shooting eventually took its toll on the throat, and it was no longer a half-inch rifle.
After rejuvenating the 221 Fireball I took a look at the throat of the 223, and decided it was time to smooth out some cracking there, too. The same basic routine was used, except only 10 rounds of 220-grit were needed to remove almost all signs of throat erosion. Also, I didn’t bother with the Dyna Bore-Coat, since this rifle’s barrel always has refused to jacket foul. When new I kept extending the number of rounds between cleaning, eventually shooting it 500 rounds several times and still never finding any copper in the bore. So now I don’t clean it at all, except for a couple of patches soaked in Hoppe’s No. 9 after every season to knock out the slight trace of powder fouling from the clean-burning charge of Ramshot TAC propellant in its standard load.
After the throat-lapping, three five-shot groups were fired at 100 yards with some Black Hills factory ammo featuring 50-grain Ballistic Tips. The groups measured 0.445, 0.626 and 0.379, for an average of 0.483 inch – but the 0.626 group had a flier, with the other four shots going into 0.202! This 223 has become the favorite gopher and prairie dog rifle of my wife, Eileen, over the years, and she’s very happy to see it shooting so well again.
Yeah, they make new barrels every day, but when a good barrel can be restored I’d just as soon not pay for another. A bore scope helps the process but really isn’t necessary, since 10 to 15 shots will smooth any throat that’s salvageable. The NECO kit costs $69.95 and the Dyna Bore Coat kit costs $44.95. They each contain enough stuff to rejuvenate a bunch of varmint rifle barrels.
The VARMINT HUNTER Magazine, a 208-page publication put together for shooters by shooters. The Varmint Hunters Association, Inc. hosts several 600-yard IBS matches, a coyote calling contest, and an annual Jamboree in Fort Pierre, SD. The Jamboree is a week-long shooting event known as "a summer camp for shooters".
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