How do I attach a “Mosin Nagant-style” scope rail to a rifle that doesn’t already have one?You'll note that these mounts are only held on by two screws. Make sure you're using hardened screws, and finer threads are better. On one of my SKSs I had the holes strip out (I didn't drill or tap that one). So you'll want to give special consideration to getting the tightest screw fitment you can.
First, you’ll need a few tools — The steel in the SKS receiver is very hard, so you’ll need some very good drill bits. (I recommend carbide for this job.). You'll also need some “gun taps”, which are made for work in hardened steel. (I ordered “EM-MS Straight Flute Mold Hand Taps” made by Greenfield from
MSCDirect.com — the 8x32 size is part number:
00353847. They were rated for use in the hardest steels — even harder steels than the “gun taps” sold on their site). Use numbered drill bits as they are more precise and allow for a higher thread percentage. A small drill press is also recommended, as is a tapping jig. All this ensures the best fitment possible for the screws.
Here’s how I did it:
- Field strip the rifle.
- Position the rail on the receiver and clamp it in place — Align the top of the rail with the top of the receiver. This is the easiest way to position the rail since you can use a straight edge to get it perfectly placed. I align to the back rail to the rear of the receiver, but you can position yours in the original position if you wish.
- Mark the hole position — I found it easiest to use a drill bit which is just slightly smaller than the mounting holes in the rail and use it to drill into the receiver about 1/64”. Be careful not to drill to far…you’re just trying to mark the receiver.
- Remove the clamp and rail, and drill through the receiver wall with the proper bit for your tap.
- Tap the holes — take it slow, use plenty of cutting oil, and let the tap do the work. Whatever you do, don’t force it. Taps break easily and broken taps are a hassle to remove. It may also be necessary to de-burr the holes on the inside of the receiver once your finished. Note: If you are hand tapping, you will need to be very carefull ensure the tap is square to the receiver.
- Test mount the rail — It’s likely that the screws which came with the rail are too long. Check to make sure that the screws do not protrude through the receiver wall and into the mechanism if the rifle. Screws can be shortened using one of those cheap electrical pliers with the built in screw cutter. Check to make sure the bolt slides cleanly past the screws.
- Permanently mount the rail. Use “red loctite” on the screws. Double check to make sure the bolt still slides cleanly past the screws.
- Trim the stock to fit the rail — Trim a little at a time until the stock is fitted. I traced the rail pattern onto the stock before I field stripped the rifle, and cut "inside of the line” to quickly get stock “roughed in”. Even then, I rushed it and didn’t get it perfect (I circled that area in the my photos).
- Reassemble the rifle.
Note: This procedure worked great for me. However, your results may vary — Don’t blame me if something goes wrong.Note: If your holes do strip out, you can always drill and tap for the next size screws. In this case you may need to turn down the screw heads on a lathe and also enlarge the through holes on the rail.
