Alliant AR- Comp 6mm br data?

[Hatrick]

Does anyone have any data for using AR-Comp with heavy bullets in the 6mm br? I can't find anything on the Alliant web site, and an internet search was not fruitful.

 

[DJ111]

In my 6BRX it runs into pressure about the same point as H4895 and both are about 1.7-2 grains less than varget when I start to get to the top end.

Straight 6br with 105's I would start at 28 grains and work up.

Good luck,
Dallas

 

[Hatrick]

Thanks for the help with powder charges.

Dave, what rifle are you getting the great groups from? I had a Rem 700 fitted with a Broughten 5C, 8 twist barrel, and it is rare that I can build any ammo that shoots like I would expect. Sadly my best groups with 107 smk has been with new brass, once fired and sized my groups open up, and there seems to be no powder charge that will make things tight. The cases have barely any run out, and my neck tension is .002 after sizing with a Forster bump nk sizer. The barrel is very finicky, which I don't think is normally the nature of the 6br...unless I am under the wrong assumption.

 

[Hatrick]

It's a BAT action, Krieger 1:8" four groove 17 contour, Shehane tracker stock. Weight is 16.5 pounds with a Nightforce 12-42 BR. On a calm day with a good lot of Berger 105 BT's a monkey could shoot in the 0.2's with it.

Nice build, and your targets certainly show that it was worth it.

As a rule do you neck size or full size your cases? I had Harrels make me a FL die to see how that works compared to just nk sizing. I also need to see if the rifle does better with other powder and primers...hence my post for the alliant data. I now have 8lbs. of AR-comp, and between the 308, 223 and the 6br, I am sure that it will not go to waste.

 

[dfry]

I am shooting AR-Comp in my 6 RAT (6.5 Grendel necked to 6mm and 40 degree shoulder), my RAT holds 37.2 grs. of H2O. I am shooting right at 28.1 grs. of AR-Comp behind a 107 SMK. gets about 2800 fps out of my 27" Krieger WOA upper xcourse gun. Haven had a chance to shoot it in the 6BR yet though. ES is about 11, SD 4. Shoots great, and very accurate for my slow prone. I shoot the same load behind 87 BTHP Hornadys for rapid fire just for ease of loading, easily holds the 10 ring or smaller in rapids. For comparison, Varget is about 29.2 grs in the RAT for a little less velocity, Dave

 

[Steve Blair]

As DJ111 reported, the series I ran with my Viper SS 6BR showed about the same velocity and charge weight as with H4895. My charge weights were a little higher but AR-Comp did not show the excellent ES/SD and accuracy that H4895 does in the Viper. Be careful when testing. AR-Comp showed strong pressure excursions near the limit.


P.S. I was shooting 105 Hybrids.

 

[FroggyOne2]

A friend of mine tried it in his 6BR with the Sierra 107's, didn't work very well, I believe that it is a lil fast for the heavier bullets.

 

[Hatrick]

A friend of mine tried it in his 6BR with the Sierra 107's, didn't work very well, I believe that it is a lil fast for the heavier bullets.

Yea, I ran it up to 27.8 grs with the 107 mk's, and did not get the groups or velocity that I did with RL-15. However, in my 308 I shot some .25 moa groups at 200 yards with 175 mk's, and got outstanding velocities. Although so far, somewhat disappointing in my 6br, it kicks ass for my 308, and I will try it next in my nm ar-15 with some 80 grainers for prone slow fire.

Just for kicks, I may go back to the 6br with the comp powder, try a different primer, and run the charge up a little higher as well. Giving up too soon is never good.

 

[dfry]

I am shooting Wolf Small Rifle Magnum primers. I would think that about 28.5-29 grains (28.5 with faster lots) would be about right in the 6 BR with 107s, like I said about a gr or so lower than Varget seems about right. 28 grs with high pressure in a 6BR seems a little strange but each rifle is different. I have found it to have outstanding accuracy with low ES and SD. but again, may not work for some. H4895 charges for me with 107s are 27.5-28 grs for about 50 fps slower velocities than AR-Comp. Also, the lot of Varget I currently have is about .5 grs. slower than previous lots I have shot. I can't shoot it in my 6 WOA and get my previous velocities, not enough room. Have to use AR-Comp, H4895 or 8208. Dave