When winning counts!
Good news!!!
Due to increased demand for this cartridge, Keystone Accuracy has contracted with Whidden Gunworks to make a competition two die set for the .240 Tomahawk.  Please click on the picture for availability.
Good news!!!
Due to increased demand for this cartridge, Keystone Accuracy has contracted with Whidden Gunworks to make a competition two die set for the .240 Tomahawk.  Please click on the picture for availability.
The .240 Tomahawk began life as an idea in the early summer of 2011 when I had gotten a bit fed up with some of the .22 cal wildcats that I built and worked with that were just not performing up to my expectations.  I had some early experience with the now more popular 6mm Hagar which was put on the map by a phenomenally talented  high power shooter, Carl Bernosky.  He won the national championships at Camp Perry a few times and was the first to have ever won it with an AR-15.  Needless to say, I have always had high regard for a cartridge of that kind of performance capability.

Later that spring, I placed a call to my friend John at White Oak Armament who also had a cartridge called the 6mm WOA which also shot very well, but lacked some of the velocity that the Hagar had been able to produce.  We put our heads together and came up with a somewhat improved cartridge temporarily dubbed the the "6mm WOA Improved" for lack of a better name at the time.  Later in the year, after much performance and ballistic testing, the .240 Tomahawk had "arrived".

For several years, the brass availability for the Hagar was nonexistent which put me in a pursuit of a cartridge that could deliver the same ultra match quality results with readily available commercially manufactured brass with minimal time spent forming at the reloading bench. 
As a result, there are currently two options for brass availability for this particular cartridge. The first option is to buy 6.8 SPC brass, which is available from several retail distributors, run it through a .240 Tomahawk sizing die in order to create a "false shoulder" by necking down the 6.8mm neck to 6mm and shoot it.  That's it!  The first firing works flawlessly with no questionable hindrance in accuracy and also blows the shoulder out to 40 degrees and forward a bit in order to get maximum powder capacity for the next hand loading cycle.  The second option is to use the now available 6mm Hagar brass available on the "6mm Hagar" tab located to the left on this page, run it through the Tomahawk sizing die and trim to the length of 1.680" (chamber length of 1.696") and load.  The sizing process of the Hagar brass in the Tomahawk sizing die forms the 40 shoulder in the brass for the first shot eliminating the need for the "false shoulder".
Both options work very well and are both good to easily achieve excellent long lasting results from the Tomahawk cartridge.

Like most high power competitors, I have suffered at one time or another from rapid fire malfunction which kept me from match wins or exceptional scores.  In those particular events, I may as well have been shooting a toy gun, shouting "BANG" after each pull of the trigger because one malfunction is all it takes to ruin an otherwise great day at the range or missed varmints in the field!  Because of the inherent feeding characteristics the parent cartridge, the 6.8 SPC, the .240 Tomahawk functions in the AR-15 platform just like its smaller cousin, the .223 Rem.  It's body diameter and balanced over all aspect ratio enhances its dependability while leaving more steel in the chamber than its Grendel based contemporaries resulting in a safer, more rigid breech area.  Because of its dimensions, the .240 Tomahawk's feed angle from the magazine to the chamber is not such a sharp one, resulting in a dependably loaded round after each pull of the trigger.


The .240 Tomahawk is a highly accurate and mechanically dependable round specifically designed for the AR-15 platform and is formed from the hugely popular and readily available 6.8 Remington SPC brass.  It shares the .421" diameter head size and nominal case length which allows for a wide range of bullet choices in a magazine length cartridge well suited for the AR-15 in which it was designed.  Dependable functionality and high velocity where the two key components that I specifically had in mind when developing this round.  It was designed as a precision target shooting round because of its capability of extreme accuracy at long distances and its greater wind bucking ability over the smaller calibers because of its ability to handle the heavy weight, high ballistic coefficient (BC) 6mm bullets.  It also suits varmint hunters extremely well because of its ability to be loaded into high capacity readily available 6.8 SPC magazines.  Its laser like speed coupled with pinpoint accuracy achieved with light varmint weight bullets can make quick work out of cleaning out prairie dog towns!

Attainable - Dependable - Accurate!!

Barrels that are normally readily availible for this and other 6mm cartridges are:

Bartlein 1:7.5" & 1:8" twist, to 28" 
(30" on special order)
Wilson 1:8" twist 
Green Mountain 1:10" twist

All barrels are 416 stainless unless otherwise noted.
Please call for pricing and availability