MN Sporter
Making the mount and installing red dot sight

My original intention was to purchase a Scout style mount from B-Square that replaced the rear sight. However when I tried to order one, everyone was sold out. So being the impatient type, I decided to try my hand at making one.

The first step is to remove the rear sight leaf. To do so, you simply tap out the pin indicated in the pic below. It is under spring pressure, so use a padded clamp to take the pressure off and the pin should slide out quite easily.

Retain the pin and leaf for later use. However you can set aside the sliding adjuster, you will not need it    .

You need a scope mount rail. Any rail with a flat bottom should work. I found the one below for a few dollars at a gun show. It is for a Marlin 336, but will work fine.

We must drill some holes in the leaf to mount the rail. (we will be re-mounting the leaf upside down) It is critical that you drill the holes accurately. The rail must line up as straight as possible with the leaf so the scope will be in alignment with your barrel. Fortunately you can do this with a drill press and a small vise. Mark the center of the leaf near one end. Place another mark a distance from that mark that matches the mounting holes on your rail. Don't worry about centering this one, just eyeball it. Place the leaf into the vise. Carefully bolt the vise to the drill press work shelf so that it is in position to drill the hole that you centered. Then drill the hole using plenty of cooling oil (WD40) After you drill the first hole, loosen the jaws of the vise and slide the leaf up so that the next hole is under the drill bit. tighten the jaws and drill the second hole as you did the first. This method will ensure that both mounting holes are close to the same distance from the edge, which should ensure that the rail mounts on straight. In the event that the rail doesn't line up, just move a 1/2 inch up the leaf and try again. NOTE: the third hole in the leaf below was intended for an adjustment screw that turned out to not be needed.

Once the holes are in place, just carefully tap the holes. I went with 8-32 screws, since I didn't have a tap that matched the attachment screws that came with the rail.

1. Below shows the minor grind out you must do on the rear sight to clear the barrel when you re-mount it upside down.
2. Shows the mounting screws ground flush so the mount can lay flat.
3. Shows the UNNEEDED hole for an adjustment screw.
4. Shows the minor grind out you must do on the rail to provide clearance for the mounting ears.
The red line shows the point I will shorten the rail too when testing is complete.

Top view shows the mount point I added. This may or may not be needed depending on the rail used. Just use the existing cut outs as a guide. Of course I will touch up all areas with black later.

Side view, better shows the cut out for the mounting ears.

To install the mount, set it in place and use a clamp to compress the spring. slide the pin in place and release the clamp.

Mounting the BSA red dot sight is just a matter of setting it on the rail with the bars in the slots and tightening the screws

While the stock spring held the mount in place fairly well, I decided to silver solder the inverted rear sight to the barrel for increased stability. Lightly sand the mating surfaces. Apply a bit of flux and use a propane torch to heat the parts. Put most of the heat onto the barrel. As soon as you get a solid bead holding the sight to the barrel, dunk the whole thing into a bucket of water. You want to work quickly so as not to overheat the barrel. NOTE: do not heat with the aluminum rail in place.

 

I was able to bring the red dot to point of aim as initially assembled, however I have added a shim made from 1 thickness of an aluminum can, placed between the inverted sight and the aluminum rail, to bring the adjustment range on the sight back near the middle of its range.

TIP: when mounting a scope on a bolt action rifle, you can get it near point of aim by removing the bolt and looking through the barrel. Put the barrel in a vise or at least set it on a firm surface with the view through the barrel on a small object some distance away. Then simply adjust your scope or red dot to the same small object. This will get you close enough that you can easily fine tune it at the range.

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