H & S Project rifle part 2 – Fitting the Picatinny rail

The EGW picatinny rail chosen for this project rifle is a well made solid section of anodised alloy. A picatinny rail has a lot of  advantages over standard type scope mounts. Properly fitted, the rail gives strength and rigidity to the action and provides flexibility to scope fitting.

With two piece mounts, as the action flexes under recoil. This flex is transmitted directly to the scope. With a picatinny rail this flex is reduced and very little is transmitted through to the scope. The rail also permits easy mounting of other items to the rifle such as lights, level indicators and angle cosine indicators.

It is also possible to remove a scope from the rifle and replace it with no loss of point of impact. This is handy when travelling or switching scopes from one rifle to another for testing. Just write down the scope settings and replace the scope to the same setting after testing.

For those on a budget. Simply buy one top quality scope and then if all your rifles are fitted with a picatinny rail you can easily switch the one scope between several rifles.

The first thing to do in fitting the rail is to loosen the action screws on the rifle. This is important and one of the most overlooked steps in fitting a scope mount. The idea is for the action to be stress free when the rail is fitted.

Next get a base screw and screw it in and out of the mounting screw holes in the action. This smooths out the thread and removes any tight spots. Check the mounting screw length on the new screws to ensure that they will not interfere with the bolt or bottom out on the barrel tenon.

Now place the rail onto the action and check for correct fit and alignment of the holes. You may notice that the rail is not a perfect fit with the top of the action and that there is some gaps between the contact surfaces. This is normal as most actions are heat treated after machining and the action tends to warp a bit.

Under recoil a base or rail can come loose as the high contact points between an action and scope base take a pounding. To avoid this the rail is better off glued down onto the action.

Lightly screw the rail down onto the action and install the bolt into the action. (make sure it is unloaded) work the bolt and ensure that the screws are not contacting or interfering with the function of the bolt. Remove the bolt, unscrew the rail  and take it off the action.

Next clean all surfaces and apply a thin film of high strength two part epoxy glue to the contact surfaces between the action and the bottom of the rail. Avoid getting any glue into the screw holes.

This glue will bed the rail to the action and fill in all the voids. This makes for the strongest possible mounting and it is very unlikely that the rail will ever come loose under normal use even if a base screw breaks or comes loose. If you ever wish to remove the rail from the action in the future then heat applied from a hot iron will soften the glue for easy removal.

Apply a small amount of grease or oil to the mounting screw threads and screw the rail onto the action. Use a torque wrench/driver to set the screws to the correct torque setting as nominated by the manufacturer. In this case 15 in/lbs.

I don’t use loctite or other thread locking compounds on scope base screw threads. If the scope mounting screws are at the correct torque setting, they will not come loose. It is the contact surface between the action and scope mounts that is the real problem. If you like you can put a small amount of Loctite under the head of the screw, where it contacts the rail.

Clean off any excess glue and put the rifle away for a few days to let the glue set to maximum strength as per the manufacturers instructions.

The action screws can be torqued up once the glue is at maximum strength. How this is done will depend on the type of stock and if the action is to be epoxy bedded into the stock or not.

Next comes the mounting of the scope.

Related posts:

1. 2010 HUNT & SHOOT Project Rifle – 7mm Rem Mag. Part 1
2. Glued vs Mechanical Optics

Category: Articles, Norman Nelson's Column