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GUNS Magazine Digital May 2011 - Page 22
• G L E N Z E d I K E R • AR-15s are pretty much pinned together, so learn to install them correctly. ssemblies ranging from the gas tube to magazine A catch, bolt stop, bolt components, forward assist, sight parts and more are secured using roll pins. I’m not trying to talk anyone into banging on their AR-15, but there certainly may be times when a part replacement is in order, and something really simple, like replacing a bolt catch with something from the aftermarket, requires little more than a small collection of tools and a little insight into the process. A roll pin is a hollow pin with a split. It’s oversized to the hole it fits into by about the gap width of the split. It squeezes down as it enters the hole and this tension keeps it in place. They are beveled on their ends but that’s often not nearly enough to get one started gracefully, and that is the trick—gracefully or not—of getting one started. Of course there is a specialty tool: a roll-pin punch. Get some. For a basic build, you’ll need Nos. 1, 2, 3 and 4. can bend. Most roll pins are a little shorter than the full span of the hole, so a sano job finishes with the pin ends at equal depths, and that should have each end a tad below flush with the part surface. A roll pin should never protrude above the surface to ensure no snagging potential. don’t Get roLLed Punch size You’ll notice there are punches of varying lengths used in the work shown and the shorter ones are a little easier to operate. The longer ones are necessary for some installations simply because they protrude freely and clearly beyond rifle parts you don’t want to accidentally miss-hit with a hammer—or have the larger diameter handle portion in contact with a rifle receiver. I often chuck up a small punch and polish its outside. They’re not all perfect, and sometimes these little imperfections are annoying, if not damaging. This is especially true when using one as a capture punch such that it has to extend fully through the hole set. Same sort of procedure for polishing most anything: spin against emery cloth until the metal is smooth. Likewise, with use they often get a little deformed around their edges, and that’s easy enough to true backup with a stone. If a punch is too small for the pin, it will tend to deform and also expand the pin end. One that’s too large may do the same and also won’t ultimately enter the pin’s hole to seat the pin’s end correctly. Use a brass-headed tap-hammer for punching punches. It has plenty enough power and a slip won’t cause undue marring. I can’t tell you much about running a punch you won’t learn on your own, Polish The ends of roll pins are often craggy, out of round, or both. These are not precision-made parts. Smooth and polish the ends of every roll pin you install. This doesn’t take much effort or time and is a worthwhile step. The easiest thing is to lightly chuck one into a drill and spin it against some emery or a stone. I do both ends but only the entry is necessarily smoothed. Removal is easier when both ends are polished. Steel pins going into aluminum holes make life way harder on the holes than on the pins. I can also tell you that a drop of oil helps and will never diminish the effectiveness of a roll pin. That also reduces any corrosive “sticktion” potentials, meaning they come back out easier. It doesn’t take much effort to drive a roll pin (with a couple of exceptions), but true hits count. They 22 Tap, tap, tap. Start the oiled roll pin using a starter punch. Drive it as far as you can with this tool. Switch to a nibbed-end punch and drive it on home. Protrusion should be equal on both sides, which means it ends up just a little below the surface. Finish with a dab of touch-up paint. WWW.GUNSMAGAZINE.COM • MAY 2011