Loading for the 6BR Ackley

[mrobles3808]

I've snooped around on the 6br pages and have yet to find the specific information I need. Unless I am completely inept to research the web, there doesn't look to be a lot of information on loading the 6bra.

My rifle will be in route soon and I have 500 lapua 6br cases to fire form. I would like to focus on using IMR8208 for the powder topped with 105-108's. If anyone has experience with this cartridge I would love to hear about your work.

 

[MDM]

I just built one for myself a few weeks back. I've got 300 rounds on it now. My advise would be don't try to push it hard during fireforming. I think you'll find most forming loads are very forgiving. Mine likes 30.4 H4895 or 31.4 Varget. Smallest groups I've ever been able to consistently shoot at 100. I do not deviate from H4350 or Varget, ever, but all the crazy records shot in the past year and a half with the bra have all been with H4895 except for one with Varget I think. So, I got a jug of 4895 and it's legit. I'd also recommend reading a lot on Accurate Shooter. While the whole trigger pinching benchrest game is not my thing, you have to respect what those guys can do and they know how to work up a uber consistent load.

 

[Sheldon N]

Fireforming for me was 29.8 Varget, 105 jammed into the lands (in addition to the natural crush shoulder headspace fit). Fireforming loads were extremely impressive accuracy and brass formed very consistent blow lengths.

Benchrest guys are shooting H4895 primarily, most common nodes are 30.6gr or 31.1gr with a 105. I'd favor the lower node if you go to 108's. Varget can shoot good too, my node is 31.4-31.6 range with a 105.

Not heard of many trying XBR 8208 with the BRA, but I wouldn't be surprised if it shot well too. My guess is a charge weight around 30 to 30.5gr with a 105 is where you'd be at. My suggestion would be to try H4895 first.

 

[Steelnecktie]

30.6 Gr H4895 is very good in my F-class gun. 20rd. groups testing at 508yds were 1.25” no wind to 2” groups with about 5 to 8 mph wind. Again, these are 20 round groups.
I’m shooting the 103 to 108 weight bullets with a 29” barrel at 2960fps.
If your looking for speed, I was able to get 3100 FPS with Varget, but accuracy was not there, about 3/4 MOA.
All loads were shot jammed .010”, creep up on loads, this little cartridge can build pressure quickly.

 

[Kadams1563]

I have a few friends venturing into the BRA and they go from great load to blowing primers with the weather change. They can seem to figure out what’s going on. They are only running them at 2900.

 

[Sheldon N]

I have a few friends venturing into the BRA and they go from great load to blowing primers with the weather change. They can seem to figure out what’s going on. They are only running them at 2900.

It can be a pressurey cartridge for sure, but blowing primers at 2900 sounds unusual. Would be curious what they find out the cause is.

 

[steve123]

Could be oil in the chamber, I was just reading about this very subject over at AS. Wet chamber from rain. Change of lot# in powder, some lot's of H4895 are noticeably faster or slower. Shorter freebore. Tighter bore. Jamming the bullet. Shorter barrel - those guys at AS are running 28"+ barrels, bullets can be driven 100 fps faster than a 24".

Every rifle is different, gotta give it what works.

 

[kthomas]

Love this little cartridge!

My fireform loads are:
- 29.5 H4895
- 105 Bergers seated 0.010" off the lands
- Lapua brass
- CCI BR4 primers

Shoots amazingly small groups, velocity is around ~2920 fps with single digit SD's.

Full power BRA load:
- 30.8 H4895
- 105 Berger Hybrids seated 0.010" off the lands
- Lapua brass
- CCI BR4 primers

This load has an SD of 4 (over 15-20+ shots), and an average velocity of ~3005-3010 fps. Also shoots tiny groups.

 

[kthomas]

My barrel is 28" btw.

 

[MDM]

That's good speed. For fireforming I used 29.8 Varget at about 2800. For full power, I can run 31.4 Varget or 30.4 H4895, its a wash as to which one is more accurate. I can't run it any hotter or I get ejector marks. I shot 6 groups at 520 alternating between each load. No wind. Groups hovered right around 1.5" for average with about the same amount of vertical. Worst was 1.75", best was .6". Really happy with it so far.

28" Bartlein
-30.4 H4895
-105 Berger H .013 off
-cci 450
2925 avg

-31.4 Varget
-105 Berger H .013 off
-cci 450
2940 avg

 

[[email protected]]

That's good speed. For fireforming I used 29.8 Varget at about 2800. For full power, I can run 31.4 Varget or 30.4 H4895, its a wash as to which one is more accurate. I can't run it any hotter or I get ejector marks. I shot 6 groups at 520 alternating between each load. No wind. Groups hovered right around 1.5" for average with about the same amount of vertical. Worst was 1.75", best was .6". Really happy with it so far.

28" Bartlein
-30.4 H4895
-105 Berger H .013 off
-cci 450
2925 avg

-31.4 Varget
-105 Berger H .013 off
-cci 450
2940 avg

What twist barrel are you using if you don’t mind me asking? Thanks in advance!

 

[MuleyTime]

I'll throw mine out here as I'm roughly 150 rounds into my 6BRA.

I've fire formed in 1 local match and more to come at:
29.8 grains Varget
105 Matchburners just touching lands
Fed 205 Primers
@2800 fps to start...but my barrel must be starting to speed up as I just chrony'd again and they are now 2845.

Started testing Full Power loads with Varget only as I have a quite a bit on hand and I don't have any H4895
I've settled on:
31.5 grains of Varget
105 Hybrids at .020 jump
Fed 205 primers
@2945 fps

100 yard testing is good....not great; which makes me want to buy some H4895 to test. Honestly, I feel the Varget load is plenty good for matches, but I'd like to see if H4895 would produce a bit tighter groups.