This is the January 2010 column by John Barsness, one of the co-authors of RIFLE LOONY NEWS, a quarterly on-line magazine available through www.riflesandrecipes.com.
SEMI-PRO SCOPE MOUNTING
Over the years I’ve seen scope mounting screwed up in just about every way imaginable, even by so-called professionals. One was the head technical guy at a custom rifle-making firm. Let’s call him Mr. Screwdriver.
Mr. Screwdriver was very firm in his opinion that one brand of scope (let’s call it Acme) was a real piece of junk. This was because he’d had so many “fail right out of the box.” His favorite was a brand we’ll call Omega. He claimed Omega scopes almost always worked correctly.
I hadn’t had nearly the same kind of bad luck with Acme scopes, so this puzzled me—until discovering, by accident, that Screwdriver was a firm believer in mounting scopes firmly, tightening the ring screws down until they literally crushed the scope tube. The tube-walls of some scopes are heavy enough to withstand such abuse, and the Omega company makes pretty heavy scopes. The Acme company made lighter scopes, and they were pretty sick puppies by the time old Screwdriver got done mounting them.
On another occasion I purchased a new Merkel K-1 single-shot rifle from a big nationally-known gunsmithing firm and retail store. It was a package deal, with a 3-10x Swarovski mounted on the rifle. I wanted to put a different scope on the rifle and use the Swarovski somewhere else, so put the K-1 in my rifle vise, selected the right screwdriver head, and…nothing happened. The ring screws didn’t budge.
Now this was an interesting situation. Evidently Torx-head screws hadn’t yet appeared in
Mounting a scope is actually pretty straightforward—literally. The scope should be lined up with the bore of the rifle, and stress-free. Before starting we should first read the instructions for the mounts, because sometimes they contain how much torque the manufacturer recommends applying to the various screws. If there aren’t any recommendations, then it surely doesn’t hurt to contact the mount maker and ask. A lot of people assume all the screws should be really tight, but as we have seen, this doesn’t work on rings. Normally base screws should be pretty darn tight, and ring screws just tight enough.
Talley, for instance, recommends 15-20 inch-pounds of torque on their ring screws. This isn’t much, since I can apply it to the Torx screws on Talley rings while holding a standard screwdriver with what might be termed “normal” pressure from the thumb and first two fingers of my right hand. I tested this with the Brownells Mag-Tip Torque Handle, a fairly expensive but accurate. Far less expensive models can be purchased, but the better the driver the more accurate its work.
I have heard many people blame Talley rings for putting “ring marks” on their scopes, but unless something else is wrong I’ve almost never had Talley rings mark up a scope tube. I can only assume other people have a problem because they tighten the ring-screws too hard.
The exception is when the tube of the scope doesn’t actually measure 1” or 30mm or whatever. This isn’t an unknown phenomenon. I’ve seen it in both “affordable” and quite expensive scopes. Slightly oversize and undersize tubes are likely to be marked by rings, the first due to the obvious reason that the rings are too tight before the screws are torqued. The second often happens after the scope shifts during recoil, when the owner cranks some more on the ring screws.
One solution for slightly oversize scopes is lapping or reaming the rings. I have mixed feelings about this, even though I own and sometimes use the equipment to do either job. Generally ring-reaming should be like turning case necks on handloads: only as much metal as necessary should be removed. This means just enough steel or aluminum to allow the scope to be mounted without stressing the scope tube.
Lapping takes longer but has the virtue of only removing a little metal at a time. Reaming is quicker but too many people go too far with it. I have a Dave Manson 1” ring reamer, but it should be used gently, and then the rings should be lapped a little to knock the edges off before mounting the scope.