Wildcat Cartridges

There has been a lot of noise and confusion around the 6.5 Grendel® and the similar cartridges that have sprung up around it. Two have surfaced that bear a closer look. The 6.5 BPC has become “the” bolt action chambering that can safely fire Grendel ammo. The differences in the chamber dimensions are minor; the 6.5 BPC was developed by Jim Borden and Dr. Louis Palmisano, the latter of PPC fame. The newest entry into this race is the 264 LBC-AR™ from Les Bear Custom, as the name implies this

Headstamped brass by Hornady

chambering is optimized for the AR platform. The biggest difference between these variations is that fact that the latter two are open use, in other words, anyone can chamber for them, like any factory cartridge.

Some sources call the BPC and the LBC cartridges “improved”. When you compare the drawings this is improved label is pretty hard to understand. There is little difference aside from the tolerances for case expansion, and the throat design. They do have a 30 degree shoulder verses a 28 degree shoulder on the Grendel, however, this will not provide any noticeable change in ballistics as the volume of the case is virtually unchanged. In fact, 2 degrees is barely outside the tolerance limits that most tool makers offer.

Ammo for the 264 LBC-AR

Black Hills Ammunition has new loads being built exclusively for Les Baer Custom at his request and with his assistance in load development. The .264 LBC-AR is loaded with a 123-grain Hornady A-Max bullet is available exclusively from Les Baer Custom. It’s designed for use in Les Baer Custom rifles as well as rifles of other manufacturers, and will also perform in rifles chambered for the 6.5 Grendel cartridge. The brass is produced by Hornady and head stamped .264 LBC-AR. Naturally this brass could be sized in a 6.5 BPC die and used for rifles so chambered.

Hornady fans have some new bullets to look at this year.  The ballistics boys at Hornady are in the process of building their line of expanding monolithic solid bullets, known as the GMX® Bullets.  This year they introduced the 6mm GMX®, weighing in at 80 grains. 

Constructed of Gilding Metal these bullets have been tested at a wide range of velocities for expansion.  Velocities from 2000 to 3400 feet per second have been tested the bullets expand up to 1.5 times their original diameter and still retain 95% of their original weight.

So why is this news?  Well, if your one of those folks who just has to use your 6mm for deer or antelope, this kind of bullet will penetrate deep and still shed energy in the target.

There are a few more of these bullets in the R&D phase right now.  The .257, .264 (6.5mm), and a .308 bullet for the 30-30 are expected to be the next in line to hit the market.  These are lead free bullets, so they will be good news for the left coast.

Quality Cartridge offers a wide variety of custom formed and headstamped brass.  For the first time there is a supplier who can make headstamped brass for your wildcat without having to order 10,000 rounds or more.  This interview gives you a pretty good idea of the brass and services available to you from Quality Cartridge.

http://www.qual-cart.com/

The 22 K-Hornet was one of the very first fire-formed “improved” wildacts.  It has stood the test of time in terms of popularity, it is still popular today to punch the chamber out on any 22 Hornet.  It’s low recoil and report make this a popular cartridge for shooter who have to worry about noise. 

Lylse Kilbourn and G.B. Crandall worked together on the Kilbourn designs including the 22 K-Hornet.  Case capacity of the K-Hornet is about 10% greater than the parent case.  Because the original case uses so little powder this improved design is more flexible in loading.  Allowing for the use of a wider variety of bullets and powders.  Of course the greatest asset of the K-Hornet is the ability to fire factory ammo to fire-form new cases.

Of current guns chambered for the 22 Hornet, the 77/22 from Ruger is a great option.  It gives you a bolt action with a removable magazine.  The conversion to this caliber is pretty simple, just bore out the chamber to K-Hornet and then modify the magazine for the fatter cases.  The magazine modification requires two changes, first the steel insert has a shoulder to hold the cases to the rear as the rise to the top of the magazine this must be moved forward to match the fire formed cases.  It can be done on a mill or with a die grinder.  Second the thimble of the magazine must be modified so the flutes will allow the fatter shoulder of the K-Hornet to ride closer to the center.