New 6mmBRA

Earlier this winter I received my second TS Customs rifle. I wanted a heavier / low recoil rifle for shooting matches. I also was starting to discover how much I loved shooting and reloading. I quickly had 700 rounds down the pipe on my 6.5 PRC. I wanted to relieve that barrel some and get a cartridge with a nice long barrel life, plus it’s a big heavy steel barrel so if / when I do replace it, its much easier on the wallet than a carbon fiber barrel.

After talking with Travis I went ahead with a 6mm BR (ackley improved). It’s a Benchmark MTU contour 7.5 twist barrel. I went with the same Impact 737 action thats on my PRC, and a Foundation Exodus stock. Hawkins bottom metal and a Triggertech diamond trigger.

I’ve been really enjoying shooting it on a few of the nicer days we’ve had this winter. I think I have a pretty good idea where i’m going to be for a load, i’m just going to wait until it warms up to 70 degrees before I load up a bunch of them. Here is a few groups that I shot at 300 yards this past weekend proofing what I had come up with. I’m shooting Berger 105 Hybrids. I had about a 3-5mph 9 o’clock wind.

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Here’s a picture showing the difference between a 6BR and then the same case after firing it in the ackley improved chamber. It gives you a little more case capacity and changes the shoulder angle from 30 degrees to 40 degrees.

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That new rifle of yours is amazing. I want one!

Nice looking dasher! I remember a few guys in collage shot those. What powder are you running?

gunsmith89 wrote:

Nice looking dasher! I remember a few guys in collage shot those. What powder are you running?

It’s actually a little different than a dasher, the dasher pushes the shoulder up the neck a little bit while the BRA just changes the angle of the shoulder.

So far I have been using H4350 and Vihtavouri N140. No real clear winner although H4350 has a little better case fill and seems like a softer recoil. I’ll probably shoot 10 of each at 600 yards on a calm day and see what has the best group and roll with it.

Varget and H4895 are definitely the popular powders for the BR cases, but I haven’t been able to find either of them in the quantities I want. Midway USA had H4895 yesterday but you could only get 2 pounds. That doesn’t really do me that much good.

On one of my hunting rifles in 270wsm I was getting similar neck/shoulder expansion. After ejecting I had to resize the shoulders quite a bit to get them to fit down the tube. I like keeping them formed to chamber, but so much pressure was doing them in. It loves fast and high pressure but after 2 to 3 loads I had the necks splitting.

I moved over to MagPro and really like the burn rate for that wsm. I slowed it down to about 3200 and the pressure wasn’t nearly as bad. I still need to full size the brass, but its nothing like the amount you have above.

Varget is such a fast burn I don’t see how that works in that round. But then there are few combinations that don’t make sense but works awesome. That H4350 has a moderate burn rate and is the winner for a few rifles I load for. In the 6mm, 270, and 280 its been very consistent for me to hit desired speeds over the chrony without reaching a compressed load.

Let me know when you want to go shooting P/dogs

Randy Wieland wrote:

I moved over to MagPro and really like the burn rate for that wsm. I slowed it down to about 3200 and the pressure wasn’t nearly as bad. I still need to full size the brass, but its nothing like the amount you have above.

The reason it looks like above is because i’m using Lapua 6 BR Norma brass and firing it in a BR ackley improved chamber. The die James and I use is a Whidden 6BRA full length non bushing die. I set it to only bump the shoulder back .0015″, so once they are fired in the chamber they definitely do not get sized way back down to 6 BR specs, that’s just showing the difference between a 6BR and a 6BRA.

Randy Wieland wrote:

Varget is such a fast burn I don’t see how that works in that round. But then there are few combinations that don’t make sense but works awesome. That H4350 has a moderate burn rate and is the winner for a few rifles I load for. In the 6mm, 270, and 280 its been very consistent for me to hit desired speeds over the chrony without reaching a compressed load.

These BRA’s are a pretty small capacity cartridge. You can only fit about 34 grains of H4350 in it with a drop tube before it starts getting really compressed. You can’t hardly get enough in it. Thats why a faster burning powder like varget can get you a little more speed, but not run out of case capacity. That said I’m not looking to hot rod this cartridge anyways both powders have really nice stable nodes around 2850 and i’m not compressed with H4350 at those speeds.

I cant wait to head out west this spring and create some red mist

I over looked your pushing those out for the AI.

Couple years ago my brother n law had a hundred rounds for his 7multra mag to burn up. Couldn’t resist blasting rats with it. Needless to say we only found a few pieces

Randy Wieland wrote:

I over looked your pushing those out for the AI.

Couple years ago my brother n law had a hundred rounds for his 7multra mag to burn up. Couldn’t resist blasting rats with it. Needless to say we only found a few pieces

I thought about buying a bunch of bullets in the 70-80 grain range for out there. Might add a little to the fun factor.

I figured I would update this, I have settle in a load for this rifle shooting the Berger 105 hybrids. I had a chance to proof it yesterday shooting at 1440 yards. Took me one shot to see my splash and correct for wind. The other 9 were all impacts on a 1.5 moa target. It’s pretty impressive what that little bullet can do. Muzzle velocity is 2850. I ended up going with Vihtavouri N140 powder. Jumping bullet 60 thousandths.