The Poor Man’s Method for Scoping Ex-Military Rifles

Many owners of military-surplus rifles would like to have a scope mounted, but there is no available drilling jig for the receiver. Or, you may not want to invest a truckload of money in drilling jigs for stuff you don’t see very often. When I started doing serious gun work (as opposed to tinkering around), I got regular calls to drill and tap guns that were not drilled and tapped at the factory. It didn’t take me very long to realize I was losing business and repeat customers because I didn’t offer this service.

However, a look at the prices of jigs or fixtures (some of which require barrel removal) told me that if I didn’t use this stuff frequently, it would take along time to pay for itself. If you are in this position, or if an oddball shows up and you don’t want to invest a fortune in a fixture to mount a scope, here’s how the poor folks do it. I have long said that the "first rule" of working on anything is that you must be at least 5-percent smarter than the item you are attempting to fix.

Keeping this foremost in mind, I deduced that I didn’t really need those fancy jigs and fixtures. It could be done with the simplest of tools. Since that epiphany, I have mounted scopes on all kinds of rifles (and shotguns), with excellent results. It really is as simple as the "first rule." Items You Will Need The first thing you’ll need is a bubble level attached to apiece of 1/8- or 5/32-inch square key stock (see Figure 1). You will also need an optical collimator (not one of the laser thingies).

Get the standard type with the interchangeable spuds; the new magnetic-type units don’t guarantee that the scope and the bore are aligned. You will need a padded vise that allows you to level the firearm’s barreled receiver and clamp it in place. Other required items include some rapid-setting adhesive such as a cyanoacrylate ("superglue") or 5-minute epoxy and a good-quality #31 twist drill. Two drill are even better. I suggest you buy them from a tool supply, not a hardware store.

Better yet, get them from Brownells or Midway. A set of 6-48 taps are required, and again two sets are better than one. A set includes one of each type—taper, plug, and bottom tap. (Taper taps have a 6-8 thread tapered lead that makes it easier to start and run true in a hole. Plug taps have a 3-4 thread taper, and bottom taps vary from 0-2 threads taper.) Get them in high-carbon steel, not high-speed steel. If you should break a carbon-steel tap, you can shatter it with a punch and pick or blow out the pieces.

High-speed steel taps do not shatter; they just peen over and are nearly impossible to get out.

It’s been my experience that broken-tap extractors for machine screws this small are nearly worthless. (If you’ve been at this for awhile, you know that you only need to buy taper taps; you can make them into plug or bottom taps easily enough on the belt sander.) You will also need a tap wrench (or tap handle, for the non-machinist types out there), some high-quality cutting oil, and a transfer punch made especially for accurately marking the center of the base-mounting holes, even those with very shallow bases (see Figure 2).

The final items required area 4-ounce ball-peen hammer and a roll of cheap electrical tape. In addition to the required items listed above, there are several tools and fixtures that are nice to have if they’re available. These include a milling machine or good drill press, a vise for the mill or drill press, a crosshair (reticle) alignment gauge, and ring-alignment gauges and tools. A couple of #31 solid-carbide Figure 1. Leveling Tool

drills, for those receivers that eat HSS drills are also nice to have. You should have two if you are drilling the holes with a hand drill; it’s almost guaranteed that you’ll break one. A tapping fixture to ensure the threads are true is a good tool to have on hand. And I recommend that you secure apiece of 1-inch aluminum or cold-rolled steel round-bar stock about 10 to 12 inches long. It needs to have a smooth surface finish, so hot-rolled steel isn’t very suitable.

How to Go About It First, remove the bolt or otherwise ensure the gun is not loaded. For guns such as shotguns or older pump and semi-automatic rifles, you will need to remove the receiver’s major internal parts (such as the bolt assembly and so forth). Thoroughly degrease the scope base or bases and the areas where they will be mounted. It all needs to be completely oil-free and dry. Place the gun in a padded vise and level it both side to side and lengthwise.

The bubble level tool is used here; most guns have some place that you can lay the key stock across to get a reading. Next, attach the proper spud to the collimator and insert it into the bore. Stand it up and get it close to vertical using the old Mark 1, Mod 0 "eyeball." Now it’s time for a bit of planning ahead. Place the appropriate screw in the forward hole in the front base. Get your #31 twist drill, and use a couple of wraps of electrical tape around the drill to indicate how deep your hole needs to be.

Ideally, you would measure the front screw protrusion through the base and drill a hole accordingly, taking into account that the area between the drill point and the drill’s diameter is essentially wasted space. Realistically, unless you are using a milling machine and can control your drill’s depth exactly, you eyeball the drill against the screw’s protrusion and mark your drill at the top of the base with the tape. Yes, at the top. That means you need to include the base’s thickness.

The reason for this will become apparent later. Once the drill is marked, remove the screw. Attach the rings to the base or bases. If your front ring is a turn-in type, you can buy a turning tool from several sources. If you don’t want to spend the money, you can use apiece of 1-inch round bar stock (my tool of choice), an old or broken scope, or a suitably-sized object such as apiece of broom handle.

Ensure the ring is as close to square to the base as you can, and center the rear ring on its base if it’s adjustable. Place the scope in the rings, leaving the rings loose enough to adjust the scope. Now place the whole assembly on top of the gun’s receiver and adjust the bases to the appropriate positions. Be sure to check inside the receiver to make sure that you won’t be drilling into something important.

Note: On bolt-action rifles with front locking lugs, do your absolute best to ensure that you do not drill a hole through a locking-lug seat. You want one hole through the receiver ring in the barrel thread area and the other hole into the cutout area that the bolt’s locking lug occupies when the bolt is closed.

If this is not feasible, drill the hole in the lug seat blind (holes that are not drilled completely through an object are called blind holes), so as to remove as little metal as possible from this highly stressed area. Once the bases look to be in position, use the level across one of the bases and adjust the scope and base assembly to level from side to side.

If you have a reticle-alignment tool, use it to square the scope’s crosshairs. (If you don’t, you can do a fairly good job with the collimator’s grid later.) Carefully make several wraps of tape around the entire gun—including the vise, if necessary—at the front scope-ring area. Re-level as needed. Look through the scope and find the grid. If you need to move the scope, be careful to keep the front base in place and level. Swing the back end to adjust.

If you have squared the reticle with an alignment tool, rotate the collimator until its grid lines match the scope’s reticle, and swing the scope sideways as necessary for alignment. If you haven’t squared the reticle, rotate the collimator and the scope until the grid lines and reticle are coincident. Back away from the scope and check to see if the vertical reticle stadia line appears perpendicular to the gun. Adjust as necessary. Move the back end of the scope side to side to center the reticle on the grid.

Don’t worry about elevation now. Now that you have established a reference point, you need to mechanically zero the scope. To do this, you look through the scope and rotate the windage adjustment until it stops or the reticle stops moving on the grid. From whichever point you just stopped, turn the windage adjustment in the opposite direction, counting the turns (or clicks) until the other extreme is reached. Mechanical Figure 2. Transfer Punches

windage zero is midway between the hard stop and the point where the reticle stops moving. Adjust the windage to that point. The same process is used for the elevation adjustment. With the scope mechanically zeroed, adjust the scope’s position to realign the reticle’s vertical stadia line with the grid’s vertical centerline, and tape around the gun/scope assembly at the rear ring area. Recheck both windage zero and scope-base level. Don’t worry about elevation.

When all is as it should be, apply the adhesive of your choice to the base or bases where they contact the gun. My favorite is Loctite Black Max #380 adhesive (available from Brownells). Don’t overdo it with the "superglues," as they don’t cure well if applied in a thick blob. After the adhesive cures, carefully remove the electrical tape and then remove the scope and rings. Leave the bottom half of the ring in place on the turnin type as the adhesive will not take the strain of trying to remove the ring half.

Use the appropriate transfer punch to mark the screw hole locations. The best-case scenario is marking all the spots without breaking the base loose. Should a base break loose before its holes are completely marked, clean the area and the base again thoroughly, removing any contaminants and the old adhesive. Replace the scope in the rings, realign as before, snug the screws, and glue again. Now you can drill the holes. Use a drop of cutting oil on the drill tip and drill the blind holes first.

Drill until the tape is even with the base and stop. It’s far easier to cope with a hole that’s a bit too shallow than to replace a barrel because you’ve drilled a hole into the chamber. (I haven’t done that, mind you, but I’ve seen it.) After any blind holes are drilled, remove the tape and drill the rest of the holes. A tip: Easing up on drill pressure just as the twist drill breaks through makes a neater hole without excessive burring and it keeps you from breaking your drills.

If you want to remove the bases and clean the adhesive from every thing, this is as good a time as any. Should you break a tap, the base will only be in your way as you are trying to remove it. Remove the rings from the bases as well. Keep everything segregated. In other words, keep the ring halves together and oriented so that they go back in the same place they were when the aligning was done. Tapping is next. Make liberal use of cutting oil when tapping.

Tap the through-holes with a taper tap, being very deliberate and attentive to keep the tap perpendicular to the work and going straight into the hole. As the tap is entering the hole to its full diameter, turn the tap carefully, backing it out one-quarter turn for every one-half to one complete turn in. This breaks the chips off that are building up on the cutting edges of the tap, and allows the tap to cut cleaner threads.

Use a shot of compressed air or solvent to clean the majority of the chips and stuff from the tap before removing it. For blind holes, you will most probably not be able to get a taper tap to even touch the edge of the hole because of its long lead taper. Use a plug tap here, and get a few threads started. You won’t get much before the tap bottoms out, but anything you get will greatly assist the bottom tap in its work.

The plug tap is more difficult to start and keep straight than the taper tap, so even more attention should be paid to keeping the tap straight. When the plug tap bottoms out, remove it, and clean the hole with a shot of air or solvent. Start the bottom tap carefully, ensuring that it is following the existing threads and make absolutely sure that it is going straight into the hole. Remove the tap after each full turn or so, clean out the hole, and relubricate the tap.

When all the holes are tapped, it’s time to clean the chips, burrs, cutting oil, and such from the gun. There will be burrs around the new holes inside the gun. They need to be removed as they can cause all sorts of problems. Now it’s time to attach the bases to the gun. Screws that go into a blind hole need to be checked one at a time to see that they tighten the base before bottoming out. Just run the screw in until it’s fairly snug and try to wiggle the base.

No wiggle means the screw is tight and not bottomed out. If it moves, the screw is bottomed in its hole. You can shorten the screw a bit or you can put the head in a drill chuck, spin the drill, and use a file to "point" the screw a bit until it holds the base without bottoming. Screws that go into through-holes need to be checked to ensure that they’re not protruding through to interfere with the gun’s operation.

Any that are too long can be shortened or replaced with shorter screws, if you have an assortment on hand. Tighten all screws snug, but don’t overdo it or use any thread-locking compound yet. Once the bases are attached, reinstall the bottom ring sections. If you have the 1-inch round stock, it’s time to see what else it does besides turn tight dovetailed rings. Lay the bar (or a cheapo scope) on the rings and put the upper ring halves in place, leaving the screws loose three or four turns from snug.

Now tighten the ring screws on the front ring evenly. Check to see if the bar or scope has lifted in the rear ring. If it has, you’ll need to shim the rear base by the amount the bar or scope has raised to align the bases. If it hasn’t, loosen the front ring screws and repeat this procedure with the rear. You can make your own shims from steel or brass stock (I prefer brass, it doesn’t rust and discolor the receiver) or you can buy shim kits from Brownells.

When your shims are in place, remove the base screws one at a time and reinstall them with a small drop of thread-locking compound. Replace the scope, square the reticle and tighten the ring screws evenly and tight. If you’re unfortunate enough to be installing vertically split rings, you tighten the rings on the bar or scope and play the adjustment game with the base-mounting screws.

It’s more difficult because you have to remove the rings in order to do any base adjustments, unless you use the 1-inch (continued on page 22)

AGCC56T AGI 56-Tape Course – new, revised (coming directly from Belvoir)

AGCC56T AGI 56-Tape Course – new, revised (coming directly from Belvoir)

round bar; it slides in and out of the rings without having to disassemble them. If you’ve done everything correctly, the scope should be pretty close to the center of the collimator’s grid. Adjust as necessary. If the scope rings or bases have windage adjustment screws (such as the Leupold/ Redfield-type bases), I use a drop of thread-locking compound on one of the screws. I then fill that screw’s AGA Corner American Gunsmithing Association News Don’t forget to check out the center spread in this issue.

Enroll in the AGI’s Complete Video Gunsmithing Course and get an instant rebate of $200. As a professional gunsmith, there’s never been a better time to expand your business, sharpen your skills, and broaden your knowledge. And if you can’t decide right now, you can always send for the introductory enrollment kit and a sample slot with red paint. If this screw stays set, the scope can be removed and replaced with excellent return to zero.

Conclusions I have used this method for mounting scopes for well over 10 years. Even though I now have drilling jigs, I used it again recently to mount a scope on a sporterized 7.7mm Arisaka for which I had no bases. The customer didn’t want to wait for them, so I cut and adapted a one-piece base to fit one-hour lesson for just $9.95. Refer to the center spread for more details. Also available are three-ring binders that hold a year’s worth of American Gunsmith issues.

Order several to house your collection safely and securely. Binders are $8.95 each (shipping and handling FREE) from American Gunsmithing Reader Services, Beachwood, OH 44122. Or call toll-free to order. Allow 4-6 weeks for delivery. the cylindrical Arisaka action, and installed it all using this method. There was no need for barrel removal—no fuss, no muss. The hardest part of the job was bending the bolt handle, as the Arisaka bolt didn’t fit my forging blocks very well.

As long as you take care every step of the way to keep everything level, and if you align the mechanically zeroed scope reticle with the collimator’s grid, the scope must be parallel with the bore. This is something that no jig or fixture can ensure. ■