Making a custom screw: Savage Model 99 fore-end repair

This Savage 99 rifle fore-end has seen better days. A previous owner over-tightened the fore-end screw and stripped out the female threads that secures it to the barrel. As it sits, the fore-end is loose, it rattles and can fall off under recoil. The current owner wanted it fixed.

For this project I ordered the following tools from Brownells:

Before we get to work, please read the following disclaimer:

The contents of are produced for informational purposes only and should be performed by competent gunsmiths only. and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.

Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.

For reference purposes, a schematic of the Savage 99 can be found here.

When the fore-end is removed, you can see the tenon that attaches to the barrel (above). While the threads at the end of the tenon have been stripped and are gone, the threads towards the bottom of the tenon are still good.

I have a few different options I can use to fix it. Normally, in machine work, if you have a stripped thread you either drill the hole out and tap the hole for the next size up; or, you use a threaded insert. The latter requires that another hole be tapped as well. Both of these require some material to work with. When you look at the condition shown above, the tenon simply doesn’t have enough metal for either of these options. Since the bottom threads are still good, we’ll make a new, longer screw to hold the fore-end on.

I wrapped a piece of painter’s tape around the shank of the screw to mark where the threads bottomed out, this allows me, along with some measurements taken from the fore-end, to calculate the length of the new screw.

Beyond the screws that you’ll find attaching rings and bases to firearms, most gun screws are specific to that firearm. That means most of the time you can’t simply run to the hardware store and buy one. If you are trying to replace a screw on a modern firearm you can often order one from a company like Brownells, otherwise, as is the case here, you need to make one.

Fortunately, Brownells makes a blank screw kit. This kit consists of a series of unthreaded screw blanks that have a small slot on the head that isn’t formed into a screw slot yet. This kit includes blanks that allow you to form #4, #6, #8, #10, #12, and 1/4″ screws with dies and a some files- something that can end up saving an old rifle like this Savage Model 99!

After a bit of measuring I determined the screw thread (8-40), length, and head diameter. The screw blank’s head was too large, so it needed to be turned down. For this I am using my Precision Matthews PM-1440GT lathe. If you didn’t have access to a lathe, you could chuck the screw shank in a drill press and use a file to grind the outside diameter down. In either case, you’ll want to get the screw blank as close to the jaws as possible to prevent it from bending.

Next, I cut the screw to an oversized length. These blanks have long 2.225″ shanks in case you need to make a long screw. I don’t, so I cut it about .25″ longer than I needed. I’ll come back and grind it to the exact length when I am done.

I grabbed the head of the screw in a pair of bronze vise jaws and used an 8-40 die to cut threads into the screw blank. I don’t get to use hand dies like this often when I work on guns and this is one application where they are ideal. They are an absolute blast to use!

Thread formed, we are ready to cut the screw to the final length. I like using this screw checker/shortening fixture from Brownells.

The screw checker/shortening fixture is a hardened piece of steel with 6-40, 6-48 and 8-40 tapped holes in it. Simply thread the screw you want to cut into the fixture at the desired length and grind off the back side for a nice square cut. Alternatively, a piece of flat stock with a drilled and a tapped hole would work as well.

A quick pass with the belt grinder and the screw is the exact length I need! More importantly, the end is perfectly square!

Finally, I need to form a slot in the blank screw head. In this case I am using some needle files. The proper files for thinner screw heads come in sets of two files. One is known as the joint file, this cuts the screw slot to the proper depth an equalling file then opens up the slot to the proper width.

A little bit of cold blue and the screw is ready for installation. Our custom made screw is to the left in the image above, the screw blank we used to make it, is shown to the right.

Good as new. Our new screw is ready for another 100 years of service! Note: It looks proud of the stock in the image above, however, it is below the surface.