6BR- Ackley Improved 40 degree

[ngb1787]

I have both. 268 turn and 272 no-turn.

Hi Alex, are using Kreiger heavy varmint #17 barrel?

 

[Alex Wheeler]

mainly, yes

 

[kvd]

Lapua 6mm BR Norma brass seems to be unavailable from the normal suppliers at the moment. In looking around, I found Norma 6mm BR Norma F-Class brass available from Bullet.com which is evidently enhanced in several ways from "standard" 6mm BR Norma brass - one of which is a longer neck.

Would there be any benefit to using this specially made F-Class brass over standard 6mm BR Norma brass in producing 6BRA cartridges? Would this extra neck length just be more to trim off?

http://www.bullets.com/products/6mm-Dasher-F-Class-Brass-Box-of-100/BL12073

Ken

 

[Alex Wheeler]

You cant use it for BRA brass, the shoulder is blown forward .080. It would be a lot of work and you would end up with sub par brass when done.

 

[Grimstod]

Using Lapua brass, what is the water capacity of this case compared to an old 6BR? Forgive me if this has already been covered but I have read this entire thread twice now and did not see any such data.

 

[pat fulghum]

6mm BRA - 39.3 gr H2O
6mm BR Norma - 37.8 gr H2O

That is what I measured... "your mileage may vary"

 

[kvd]

6mm BRA - 39.3 gr H2O
6mm BR Norma - 37.8 gr H2O

That is what I measured... "your mileage may vary"

Just to make sure I'm not misinterpreting your results. The measurements are in grains not grams - correct?

So 39.3 and 37.8 grains would be 2.547 and 2.450 cc's respectively.

I just think better in cubic centimeters for volumes.

Ken

 

[Rtheurer]

Your Likely correct.... However... The industry standard is Grains in H2O and that is what we all relate to. So you could say Cubic Centimeters and we would all look at you like you have a Horn growing out of your head.

 

[pat fulghum]

Grains water is what quickload software uses.
I use Woodinville WA tap water.
It's mineral content has been carefully calibrated and is only available to a select few

 

[Sheldon N]

I dunno, I'm pretty sure that Woodinville, WA tap water is made up of liberal tears. I think you have to get further to the east side of the state to get pure water.

 

[dbduff]

I dunno, I'm pretty sure that Woodinville, WA tap water is made up of liberal tears. I think you have to get further to the east side of the state to get pure water.

Now, that's about the funniest thing I've read all day, but I don't get out a lot.
D

 

[pat fulghum]

I dunno, I'm pretty sure that Woodinville, WA tap water is made up of liberal tears. I think you have to get further to the east side of the state to get pure water.

I do feel like a fish out of water over here on this side of the Cascades.

I came from a state where you don't need a permit for concealed carry.

I can't even begin to explain how different it is over here.

 

[R.Morehouse]

I do feel like a fish out of water over here on this side of the Cascades.

I came from a state where you don't need a permit for concealed carry.

I can't even begin to explain how different it is over here.

There are most likely some mushrooms growing in your yard that will make you OK with the whole scene......

 

[dbduff]

There are most likely some mushrooms growing in your yard that will make you OK with the whole scene......

That's pretty funny too!
D

 

[X-Caveman]

26" but it is where it shoots good not where velocity is the highest, it can go a lot more but I never pushed it 3250- 3300 it is a sub.1 gun. Jim

I did some chrono work yesterday with XBR8208 & Berger 80gr FB about .01" longer than my touch #. 28" Krieger, 12 TW, .236" 4 Groove, .104" FB. 59 rounds down the pipe when I started. Once fired brass, Russian Mag primer, 83deg out.

30.5gr was 3,095 FPS (both FF and 1x F brass). Went all the way to 32.9gr @ 3,341 FPS and never did get pressure. I'm just gonna load 50 up around 3,275 and shoot a 300 yard clay match this weekend. At that point, my barrel should be broken in so I can start load work in earnest. I think I'm going to like this as a short range, fun match barrel!

 

[Webster]

Has anyone ever experimented with just blowing out the shoulder of a standard 6BR to 40 degrees? No, I'm not talking about a Dasher or BRDX where the shoulder is blown forward 70-100 thou and has a 40 degree shoulder. My winter project is an Improved 6BR that has the Ackley benefits, but much easier to make than the existing improved BR's. P.O. Ackley's theory with the 40 degree shoulder and very little body taper was: better combustion chamber, more stable brass, less bolt thrust, less case growth, more velosity with less pressure. This Ackley Improved round will headspace on a new standard 6BR (Lapua) case at the neck/shoulder junction. So, there is no case prep. hassles associated with blowing the shoulder forward. There is safety issue with blowing the entire shoulder forward: this is case stretch. If not fireformed correctly, the case can stretch at the web, leaving it thin in that area. A thin web can rupture and blow brass, powder, and hot gasses back in the face of the shooter. I have witnessed this first hand: it is not pretty. If anyone can shed some light on this experiment let me know. And if you or know of someone that has a reamer or dies for this animal let me know. Thank you, Samuel Hall

Your should jam the bullets when fire forming so the case head is always against the bolt face. If you stretch the case near the head your doing something wrong. False shoulder method accomplishes the same thing. Seems easier to jam if it's appropriate for your particular cartridge.

 

[holstil]

I'm thinking you don't need to jam. The brass should fit snug.
At least that's the way I chamber my other AI's.
You got .004" from go to no go.

 

[johara1]

I did some chrono work yesterday with XBR8208 & Berger 80gr FB about .01" longer than my touch #. 28" Krieger, 12 TW, .236" 4 Groove, .104" FB. 59 rounds down the pipe when I started. Once fired brass, Russian Mag primer, 83deg out.

30.5gr was 3,095 FPS (both FF and 1x F brass). Went all the way to 32.9gr @ 3,341 FPS and never did get pressure. I'm just gonna load 50 up around 3,275 and shoot a 300 yard clay match this weekend. At that point, my barrel should be broken in so I can start load work in earnest. I think I'm going to like this as a short range, fun match barrel!

With 8208 XBR I think the lot to lot variation is a quite noticeable in some cases. Remember it was used in the PPC. to start with and has slowed down a bunch over the first lot. It still does shoot good with the light bullet and I have had some success with the 103's with it, but I need a little more time with it. ...... Jim

 

[kvd]

With 8208 XBR I think the lot to lot variation is a quite noticeable in some cases. Remember it was used in the PPC. to start with and has slowed down a bunch over the first lot. It still does shoot good with the light bullet and I have had some success with the 103's with it, but I need a little more time with it. ...... Jim

johara1,

Would not Accurate LT-32 be something to consider with 103 to 105 grain bullets in the 6BRA? According to the Accurate website, LT-32 was formulated to emulate the shooting characteristics of the mil surplus 8208 that has been used successfully for years in 6PPC with lighter bullets. My understanding is that 8208 produces higher MV than IMR 8208 XBR so the LT-32 may be an option. When my new barrel gets here, thinking of fire forming my 6BRA cases with approximately 30 grains of LT-32 and Berger 105 target VLD's seated 0.005 inch into the lands since I have a decent supply of LT-32 on hand. Has anyone else given LT-32 a shot?

Ken

 

[R.Morehouse]

Yeah......What he said. I have a crap load that i use with the 6PPC. I would like to know as well for the yet to come BRA........