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GUNS Magazine May 2012 Digital Edition - Page 50
John Barsness ver the past quarter-century a revolution took place among hunting rifles. No, they didn’t rise up and start shooting all by themselves, as many antigunners apparently believe possible, but their basic materials started changing from blued steel and wood to stainless steel and various stock materials generically known as synthetic. (Of course, not all rifles turned stainless/synthetic. Hunters are almost by definition conservative, Hunting in snow and cold creates extra demands on a hunting rifle. and many haven’t accepted silver barrels and “plastic” stocks. Luckily, they don’t water, stainless steel develops a tiny layer of chromium oxide. have to since, amazingly, blued steel and Unlike rust, this doesn’t continue to grow, so protects the steel checkered walnut still work in the woods.) from further oxidation—at least under most conditions. O Hunting Rifles Field Care For Many modern hunters believe stainless/synthetic rifles don’t require any maintenance beyond obsessive bore cleaning. Other than scrubbing the barrel like a pool player on methamphetamines every 15 or 20 rounds, the theory is that stainless/synthetic rifles don’t require any special care. Stainless steel derives its rust-resistance from relatively large amounts of chromium in the alloy, from 10.5 percent to 30 percent instead of .5 percent to 1 percent in “normal” steels. Instead of forming rust (iron oxide) when exposed to Some duct tape and quick-setting glue saved a hunt when this Marlin’s buttstock was run over by a pickup tire. 50 Unfortunately, really high-chromium steels don’t work very well in firearms. The most common stainless alloy used in rifles is 416, with a chromium content of 12 to 14 percent. While 416 machines well, the relatively low chromium content allows it to rust under extreme conditions, especially when exposed to salt or low-chromium steel. Twenty years ago I went on a horseback hunt in Montana’s Bob Marshall Wilderness with an outfitter friend, the late Richard Jackson. Another hunter on the trip had a brandnew stainless/synthetic rifle, and after a few days he got pretty upset when red rust started forming on the barrel of his supposedly maintenance-free rifle. The reason turned out to be the leather rifle scabbard Jackson provided, which had been soaking up salty horsesweat for a decade or more. The problem was compounded by the barrel’s bead-blasted finish, considered necessary by most hunters to prevent spooking game. Bead-blasting creates tiny irregularities in the steel’s surface, and these hold moisture longer, encouraging rust. (The polished interior of a 416 barrel is far less likely to rust than the bead-blasted surface, but can still corrode if exposed long enough to the salty air of seacoasts—or saltwater itself.) Another common cause of stainless-steel corrosion is contact with damp low-chromium steel. It’s common to find non-stainless parts in supposedly all-stainless rifles, especially in the bolt, because low-chromium steel is less prone to galling. Stainless steel parts can gall (bind) when two parts fit so tightly together the chromium oxide gets wiped off, increasing friction between the parts. Making one of the parts from low-chromium steel reduces galling, the reason the bolt or bolt-head in some stainless rifles is made of lowchrome steel. W W W. G U N S M A G A Z I N E . C O M • M AY 2 0 1 2