GUNSMITHING SERVICES: Tactical Bolt Knob installs for various manufacturers

Having a customized bolt knob installed on a bolt action ranks as probably the single most popular way to personalize a rifle.  This upgrade is performed every day by hundreds of smiths all over the country.

 

The Remington Model 700:

Not all installations are created equal.  The traditional process is to fixture the bolt in a lathe and machine the “football” (factory knob) into a cylinder that can be threaded.  The problem lies in the manufacturing of the handle itself.

Remington handles are made from cast steel.  Very high quality castings, but cast none the less.  It’s well known among smiths that the knob portion of the handle is frequently plagued with casting imperfections. The reason why is due to how the handles are made.  

The lost wax casting process is an industry proven way to mass produce parts affordably.  A wax “plug” is cast from an aluminum or steel mold.  From here the plugs are bonded to “trees”.  These are then dipped in a porcelain like material over and over again forming an “egg shell” on the outside of the wax plug. Finally, they are fired in a kiln where the wax melts away (lost wax process), the porcelain hardens, and a hollow cavity remains.   

Extremely hot liquified steel is poured into the handles via “gates” and the part is formed once it cools and solidifies.  The problems can start as the molten material rushes down the length of the handle.  It picks up velocity because the chamber narrows.  As the steel begins to fill the knob feature of the handle the higher velocity material behaves much the same as air moving through a venturi of a carburetor. This turbulence is what creates the conditions for voids in the handle/knob to form.

When this happens (and its so common you quickly learn to expect it) the turned cylinder portion of the handle can be riddled with porosity leading to strength issues.  There is a long historical record of tac knobs snapping off the handles of M700s and it’s almost always for this very reason. 

For some, the solution is to drill and tap down the center of the handle so that a small threaded shaft can be installed to reinforce the weakened area. This has proven to work, but we use an alternative method that we feel is better because it completely solves the problem by getting rid of the flawed material.

LRI tac knob installs start by completely eliminating the factory Remington knob.  From here the handle is milled flat, drilled and tapped for a heat treated thread insert. Our inserts are grade 12 socket head set screws.  We turn and machine one side for the handle and leave the “big side” alone so that knobs direct mount.  They also feature an allen hex socket for ease of assembly.

 

 It’s a proven process as we’ve installed thousands of these for clients. This work is performed in a vertical mill using a vice that completely captures the bolt handle.  The improved work holding translates to clean surface finishes with features precisely located.

 

When completed, the LRI tac knob presents as a robust, simple, and clean way to personalize your rifle.

 

Howa 1500 and Howa 1500 Mini Action

Howa bolt handles are cast as well, but because of the overall shape difference, the design does not appear to be plagued with the issues associated with M700’s.  Because of this LRI machines the handle into a cylinder and threads it.

 

The result is a very neat/clean presentation that adapts to most any knob geometry elegantly.

The steel is fairly tough so the requirement for a threaded insert is avoided.  The heat treatment in fact does not allow for trivial setups.  because of this, we choose to do the work in a vertical milling center rather than a lathe.  It just better supports the handle and finishes are more predictable. 

 

 Model 70 Winchesters:

M70’s present the greatest machining challenge for bolt knob installations.  Tough steel and the slender geometry invite tool chatter.  Work holding is also a factor because the handles are not the most consistent in overall shape.

Again we rely upon our vertical milling centers because of the flexibility in tool path creation.

Because Winchester bolt steel is very tough and free of casting inclusions, we are able to direct thread the handle.  the OEM knob is machined into a cylinder and threaded.

Below are photos showing the work done on the 2014 Sniper’s Hide Cup Trophy rifle donated by LRI and awarded as the top prize of the event to the match-winner. Bryan Morgan was the recipient that year.

The knob was a custom machined stainless steel piece.  While we can certainly offer this to clients, it does come at an added expense.

 

 

NOTES:  This a service.  The price of the knob is not included.  LRI is happy to install a knob made by another manufacturer so long as it has a 5/16-24 threaded socket. (most do as this is the most popular size)

LRI Tac Knobs can be found here:

LRI TACTICAL BOLT KNOB

 

LIMITATIONS:

Remington M700’s have evolved over the years.  Certain legacy versions use a handle design slightly different from the current design.  These older handles have a very narrow transition to the bolt knob and lack the material needed for our inserts to install.  If your bolt is of this lineage the handle will have to be replaced with the current version in order for us to install our knob.  We carry these as a normal stock item and will consult with you well in advance of performing any work.