Rimrock BRMXD and BRM-MF


Just a sneak peak iPhone photo of the tang of the new Rimrock BRMXD action.  The tang of a Rimrock BR is on the right as a comparison.  The XD version of the BRM action is 1.470 in diameter and is round.  It is available with no recoil lug, with a pinned on recoil lug in front or with a bolted on recoil lug on the bottom.  Screwed and pinned 20 MOA and 30 MOA aluminum picatinny rails will also be available.  We are taking orders for these now for delivery in January and February 2016.  We will also very soon have a 1.4 inch multi flat version of the BRM.  keep watching here for the announcement.

Action and Bolt PVD Treatment


Effective immediately we are offering PVD treatment of bolts and/or actions.  The treatment is available as “BlackCat” which is a matte black or AlTiN which is between black matte and dark gray.  The surface has a Vickers micro hardness of 3500 and it aids in corrosion protection of the chrome moly bolt body and adds more slickness to an already slick action.


Treatment of bolt only is $80 and treatment of entire action, bolt and shroud and recoil lug is $300.00

Jesse Rigsby Wins UBR 2015 Score Shooter of the Year


Congratulations to Jesse Rigsby for winning the 2015 UBR Score Shooter of the Year Title as well as setting three new UBR Records with his rifle built using a Borden Rimrock BR action.  He steered the rifle to set a new UBR 100-300 yard score record, a new UBR 100-200-300 yard UBR Score Record and a new UBR 200-300 yard score record.  Keep up the good shooting Jesse and thanks for your confidence in Borden.

PVD Coated Bolts


Our bolt bodies are made of hardened chrome moly steel and the bolt handles and shrouds are stainless steel.  Many of our customers have shown great interest in getting the bolts coated to assist in helping to prevent hazing or oxidation on the bolt bodies during hunts and storage.  There are many topical coatings out there and most of them add thickness.  I have had great luck with Xylon Coating and Herb Coates of HC Precision of Govenour, NY has been my choice for doing that coating.  It is a slick coating that is matte black and gives good service.  Some customers have used Ceracoat and I find that satisfactory on the external metal surfaces of rifles.  However, I do not like the bolt body or inside of the action coated with Ceracoat.  We have been pursuing options for having the bolts treated so that no thickness is added and at same time improve our already slick operating bolts.  I am happy to report that we have had success in finding a source for that type of bolt treatment.  The above pictured bolt is a bolt treated with Blackcat.  It has a micro surface hardness of 3500 Vickers and the coating is extremely durable.  We will also be able to offer the treatment in  CrN which has a silver gray color.  It has to be done in batches of 25 to 30 bolts at a time so we will be soon deciding on black or the CrN.  Input on preference of Black or the silver/gray would be appreciated.


Jim Borden


Thoughts on 338 Lapua Versus 338 RUM

I have had numerous requests for either rifles built in 338 Lapua or actions for the 338 Lapua. Currently, I do not make my standard actions (Timberline, Timberline Magnum or Rimrock LSR) to accept the 338 Lapua case. I have two primary concerns about making the actions at their current dimensions to accept the 338 Lapua round. The first concern is that the bolt nose edges on a .7000 diameter bolt will be very thin and fragile with a 338 Lapua Boltface (.595) and the lug shear area even though it is greater than a Rem 700 seems marginal to me for the 338 Lapua and its bolt thrust. The second area of concern is the thread tenon diameter. The actions have a 1 1/16×18 thread and the barrel would be threaded the same. The root diameter of a 1 1/16×18 thread is about .990 inch. With a chamber diameter of .595, this leaves a wall thickness of .1975. Using a simple of model of the tenon alone and Chamber pressures of 65,000 psi results in a hoop tensile stress in the barrel tenon of 94,000 psi. The yield strength of 416R Stainless steel at 26 Rc is about 107,000 psi. So the SF (Safety Factor) for this application is only 1.1 which is well below what is recommended minimum of 1.5.


So, it would seem that unless a stout action is used, that someone wanting to use a 338 in a hunting weight rifle would be at a disadvantage. However, a closer analysis of the 338 Lapua versus the 338 RUM shows that this is not the case. The following table shows a 338 RUM versus a 338 Lapua for bullet weights from 210 Grains up through 300 Grains. The table shows that the 338 RUM delivers equal velocities with less powder and less recoil up through the 250 Grain bullets. Therefore, the only time a 338 RUM would be at a disadvantage over a 338 Lapua is for the 300 Grain bullet. The 338 RUM can be safely built in a rifle that uses standard profile actions, barrels and stocks and a 6 ¾ pound rifle (less scope) can be easily built that will deliver sub ½ moa accuracy while at the same time delivering significant muzzle energy for longer range shooting.

So the question for me would be: “Why would anyone want to use a 338 Lapua for a hunting rifle when a 338 Rum can be built in a much easier to carry rifle that will deliver equal velocity at less recoil?”

Firing Pin Disassembly

Jim Borden demonstrates use of Bolt disassembly tool to remove firing pin assembly from bolt of Rimrock, Alpine and Timberline actions. He then demonstrates how to disassemble the firing pin unit for cleaning and/or spring replacement.