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6XC Essentials 1. Has won the NRA High Power
Rifle National Championship (across the course) the
last four years. 2. With the 115 gr. DTAC it
is now a viable long range cartridge -- won 2004
NRA High Power Long Range Rifle National
Championship 3. This means that one can
now use one cartridge/rifle for all events (other
than Palma) Loading for the 115 gr. DTAC bullet in the 6XC Water capacity of the Superior Shooting Systems Inc. (DTAC) 6XC case is just under 50 grains capacity. Case neck length is .305 inches so a 115 gr. DTAC bullet seated .015 inches in front of the neck-shoulder junction will have .290 inches of neck support at the start of use in a newly chambered barrel. This allows one to keep seating the bullet outward as the throat wears and yet have plenty of case support for the bullet over the life of the barrel. I have used less than .170 inches of neck support with good results when feeding out of the magazine. Seating the 115 gr. bullet approximately .015 inches in front of the neck-shoulder junction gives an approximate overall length (OAL) of 2.750 inches, which will allow you to grow your round (for magazine feeding) more than .100 inches when using a T2K magazine. Click HERE to learn more about our 6XC brass. The 115 grain DTAC has approximately 10 points lower BC than a 142 gr. 6.5mm Sierra. Everybody's BC calculations vary so I believe this is the best way to evaluate it against the 142 gr. 6.5 Sierra. (Also if you look at the Berger 115 6mm keep in mind that Bergers BC's are not conservative at all.) This means that if you shoot the DTAC 115 at 3000 fps verses the Sierra 142 at 2950 fps then the drift at 1000 yards is virtually the same. I use moly-coated bullets exclusively, so the loads listed need to be reduced 1-1/2 grains if an uncoated bullet is substituted. All of my long range loads are seated long and are pushed back into the case upon the closing of the T2K bolt. All of my long range loads are full-length resized each and every time (approximately .003 inches shoulder set back). Dies used are those found in the Superior Shooting Systems Custom 6mmXC die set. I have been using Russian primers exclusively. Be sure they are seated into the case -- if not they can be hard to ignite. Russian primers use a different sinoxide compound (closer to the European type), which, in my testing, consistently delivers better extreme spreads over Federal 201Ms. I neck turn all of my long range brass and clean it up to approximately a 60-percent level -- I just try to eliminate any overly thick necks or high spots. I used the .268 bushing in the sizing die with the expander plug (for long range only; I use a smaller bushing for across the course rounds). I tried Hodgdon H4831 but could never get the velocity I wanted out of a 27-inch barrel; with this powder velocity without any brass flow (shiny spot) on the ejector plug was around 2930 fps. (4831 might be worth a try if one has a 32-inch barrel). I ended up with H4350 -- the same powder I use with my 107 gr. Sierra bullets in this cartridge. I use the ejector plug brass flow as my pressure indicator -- when I see a shiny mark on the case head I automatically back off the charge 1/2 grain. I have shot the DTAC 115 at over 3100 fps but saw too much pressure. I can shoot this 115 at 3050 fps and have a reloadable/reusable case; however, out of my 7.5 twist barrel it did not shoot as well as when I backed the load down another 1/2 grain to 39.6 gr. of H4350. This gave a velocity (depending on temperature) of anywhere from 2988 to 3020 fps. When I got home from Camp Perry I rechronographed the ammunition I used there and it was going 2990 fps (early morning, cooler temp.); mind you, this was several hundred rounds later in the barrel's life. I have shot many calibers over the years and have only seen the .308 Winchester be as easy to load for as the 6XC. When I started playing with the 115 gr. DTACs at 1000 yards I could immediately tell that when one gets the unexplained shot (that occasionally happens) the 6XC is much more forgiving in the result -- which means instead of wide 10 or even a 9-ring shot, the 6XC's bad shot is a mid-ring 10. I shot four different 6XC barrels (three were 7.5 twists and one 8 twist) this past season and they all shot the same. I did quite a bit of testing at 1000 yards -- 20-shot groups prone -- and the best group (27-inch barrel, 7.5 twist ) was 5.5 inches elevation for 20 shots (group was about 15 inches wide -- wind was blowing but somewhat steady and the target was marked after each shot) The group shown in the photo was shot with a 29-inch barrel (7.5 twist) and the conditions were almost calm -- also keep in mind that I can't hold much better than a 3-inch spotter when shooting prone at 1000 yards. I feel that the 6XC cartridge will continue winning for some time to come since it now offers a good long range bullet with a decent BC, lower recoil than a .308 or 6.5x284, and because of the fact that it is a very easy cartridge to load for (make shoot very accurately). -- D. Tubb |
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