By Chuck Hawks
One problem that the owner of a wildcat 6mm-06 rifle will not have any time soon is a shortage of .30-06 brass to neck down. The 6mm-06 is based on the most popular cartridge in the world. It is a simple process to neck down 30-06 (or even better .270 Winchester) brass to accept .243" diameter bullets. Trim to 2.494". The result is a 6mm-06 case.
Like all wildcats, there is no official SAAMI pressure limit for the 6mm-06, nor is there a set cartridge overall length. In this situation, the chambers of rifles can and do vary, which affects pressure and velocity--a fact that reloaders should never forget.
The 6mm-06 became popular shortly after the introduction of the .243 Winchester in 1955, which made a good selection of 6mm bullets widely available to reloaders and wildcatters. Certainly experimenters had necked down .30-06 and .270 Winchester cases to accept 6mm bullets long before 1955, but it was the .243 Winchester that really brought the .24/6mm caliber into the limelight. The 6mm-06 has gained in popularity ever since, and has become one of the most popular wildcats. The introduction of ever slower burning powders has made this once seriously over-bore cartridge a viable proposition.
I have had a modicum of experience with the 6mm-06 myself; this was many years ago when I was still in the USAF and a roommate owned a 6mm-06 rifle. I must say that at 200 yards the bullet seemed to get there at nearly the same instant the gun went off, much like with the .240 Weatherby Magnum. (The actual time of flight to 200 yards, according to the Speer Reloading Manual, is 0.2022 seconds for a 105 grain spitzer bullet at a MV of 3200 fps.)
The 6mm-06 is at its best with the heaviest bullets in the caliber. The 100 grain and 105 grain spitzer bullets are a particularly good choice for medium size big game at long range.
The 105 grain bullet can be driven to a MV of around 3200 fps. 6mm-284 data can be used as a starting point for working up 6mm-06 loads. As always, and especially with a wildcat cartridge, start with the minimum load and work up slowly, checking carefully for signs of excess pressure. Verify results with a chronograph, and stop testing immediately if you get unexpected velocities. (If you are reloading for a wildcat cartridge, a chronograph is a necessity.)
At 3100 fps the ME of a 105 grain bullet is about 2240 ft. lbs. The 200 yard figures are 2663 fps and 1653 ft. lbs. The trajectory of that load looks like this: +1.5" at 100 yards, +2.3" at 200 yards, 0 at 258 yards, and -3" at 305 yards.
Note: An article about the 6mm-06 and 6mm-284 can be found on the Wildcat Cartridge Page.
Copyright 2005, 2012 by Chuck Hawks. All rights reserved.