Riding the Picatinny Rail

You may recall a while back that a correspondent e-mailed me about his .22/250 which refused to group after only 750 shots, and whose barrel, his gunsmith said, was worn out. I told him that it sounded like copper fouling, and get a jar of J-B Bore cleaner, and scrub the hell out of it. He did, and said he got out a ton of copper that he never suspected was there, and that the rifle shoots fine again. It takes a heap o’ shooting to burn out a barrel. I’ve had a spate of scorched tubes recently, but these were rifles that had been in use for 25 to 40 years.

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I noted at the 2015 SHOT Show that Picatinny Rails are now trendy, and are being used on sporting rifles. This is fine; the rail has a couple of disadvantages, but it’s a very good way to attach a scope to a receiver. The rail got its name at the Picatinny (NJ) Arsenal, which tested and designated it as Mil-STD-1913 in 1995. It’s a modification of the Weaver mount, and differs slightly in its dimensions, and in that all its dimensions are standardized.

How does it differ from the Weaver system? Permit me to quote from the excellent explanation on the Brownell website:

“Now, what does this mean to you? Boiled down, it means that accessories designed for a Weaver system will, in most cases, fit on a Picatinny system. The reverse, however, is probably not the case. Due to the larger recoil groove, Picatinny accessories will not fit a Weaver system. There are, of course, exceptions to every rule, but for a good rule of thumb, Picatinny won’t fit Weaver, but Weaver will fit Picatinny.”

Its disadvantages are weight (although Nightforce is now selling very light Picatinny rails and rings) and ugliness. Also, since there’s no windage adjustment built in, if your barrel is out of line with your receiver, you may find it impossible to line up your scope’s crosshairs.

On the plus side, the Pictatinny is probably the strongest of all mounting systems due to the massive size of its parts, generous bearing surfaces, and the fact that the base is one piece of metal held to the receiver by four screws rather two pieces held by two screws each. The Picatinny gives you more fore-and-aft flexibility in mounting a scope than anything. If nothing else can get the ocular lens bell far away enough, or close enough, or accommodate weirdly-spaced adjustment turrets and lens bells, the Picatinny will.

There are all sorts of companies making Picatinny systems, but the one I've used the most is made by Farrell Industries. Mr. Farrell got his start in the aerospace industry, and his bases and rings are masterpieces of the machinist's art. Farrell makes bases and rings for just about everything that goes bang, and also offers angled bases in case you'd like to join the long-range horde and your scope doesn't have enough come-ups in it.

Farrell is also extremely helpful if you’re confused and don’t know whether you want a flat base or a 10 MOA base or a 20 MOA base. They will walk you through it.

In case you really want to get anal about it, you can take your rifle and Picatinny base to a gunsmith and have him profile the base so that it fits the receiver perfectly, and then epoxy bed the base. And, while you’re at it, have the receiver drilled for 8x40 screws and have them red Loc-Tited in place. Beelzebub himself could not shake that arrangement loose.

I’m at the point now where I’m using lightweight Picatinnys on sporting rifles. They work terrific, and handsome is as handsome does.