6BR- Ackley Improved 40 degree

[Curmudgeon]

I shot a match today and one of our shooters had a new rifle chambered in
6 bra. 6br Ackley. He said it is the poster child of the 1000 yard Montana boys. His Stock also had a very nice adjustable keel on it. A wood Shehane
Stock with drop port Stiller. He is using 4895 and says it tunes very easily. He said this cartridge recently shot some new 1000 yard records. When the scores come out I will post for comparison.

 

[KenOath]

Fireformed 24 pieces of brass today running 30gr of ADI2208 behind 95gr Berger VLDs. Averaged 2930fps out of a 30" Krieger barrel. Barrel now has 100 rounds through it. Dropped 2 shots due to vertical but a Labradar showed 1 shot at 2914fps which put me fractionally low, and 1 shot fractionally high at 2948fps, enough to make a difference at 800. Everything else hovered around the 2930 mark and went into the X ring. Now that my cases are fireformed, I'll run some Berger 105 Hybrids and Nosler RDFs through it to see how it goes. Just a really enjoyable cartridge to play with and so efficient on powder.

Gday Willow,
if you don't mind me asking what reamer specs did you go with?
Im in the process of getting the bits I need to chamber for BRAI.. looking forward to it.

Cheers Rushty

 

[Willow]

Gday Willow,
if you don't mind me asking what reamer specs did you go with?
Im in the process of getting the bits I need to chamber for BRAI.. looking forward to it.

Cheers Rushty

Hey Rushty, couldn't tell you sorry mate. My gunsmith (MattP on here) came up with the specs for a reamer. I just trust the quality of his work and knowledge. I have't truly played with this cartridge yet, only really finding the time to fireform a case of Lapua brass, but I've got several loads and bullets worked up to run at 300 metres this weekend. Conditions will hopefully be friendly so I hope to be able to draw some conclusions. So far out to 100 metres it has basically punched a 1 hole group during fireforming, and showed very promising signs at 600 and 800 metres also during fireforming.

I've got some Nosler RDFs and Berger Hybrids loaded up with RL15, both jumped and I'm also going to try some of the Noslers with ADI2206H and some Berger 95gr VLDs.

 

[KenOath]

Hey Rushty, couldn't tell you sorry mate. My gunsmith (MattP on here) came up with the specs for a reamer. I just trust the quality of his work and knowledge. I have't truly played with this cartridge yet, only really finding the time to fireform a case of Lapua brass, but I've got several loads and bullets worked up to run at 300 metres this weekend. Conditions will hopefully be friendly so I hope to be able to draw some conclusions. So far out to 100 metres it has basically punched a 1 hole group during fireforming, and showed very promising signs at 600 and 800 metres also during fireforming.

I've got some Nosler RDFs and Berger Hybrids loaded up with RL15, both jumped and I'm also going to try some of the Noslers with ADI2206H and some Berger 95gr VLDs.

No problem mate, good luck with it.

Cheers Rushty

 

[Terry Altom]

That's .0056 per 100 rounds not far off of my .007 per 100

So, considering the throat erosion being around 6-7 thousandths per hundred, would it be a decent strategy to start a new barrel at say .060" freebore and measure it about every two hundred rounds or so. Then use a PTG unithroater to cleanup the throat as it grows? Just thinking out loud....

 

[johara1]

So, considering the throat erosion being around 6-7 thousandths per hundred, would it be a decent strategy to start a new barrel at say .060" freebore and measure it about every two hundred rounds or so. Then use a PTG unithroater to cleanup the throat as it grows? Just thinking out loud....

every time you move the throat the load changes, you are treading water....... Jim

 

[saunaking]

So, considering the throat erosion being around 6-7 thousandths per hundred, would it be a decent strategy to start a new barrel at say .060" freebore and measure it about every two hundred rounds or so. Then use a PTG unithroater to cleanup the throat as it grows? Just thinking out loud....

My reamer has .0125 freebore. I started out using the EPS bullets (107 grain) with about .0012 jump, and shot about 800 rounds through the barrel last year. The 105 hybrid has been used since this spring with .0025 jump. There is 1140 rounds through the barrel now and I have not had to change seating depth on the hybrid yet. I'm either not getting much throat erosion or the bullet doesn't care how much jump it is getting into the lands. Shot a clean with a good X-count on Monday night at 600 yards. One of these days I should measure it and see how much it has moved.

 

[Terry Altom]

every time you move the throat the load changes, you are treading water....... Jim

This is my concern over throat erosion and trying to maintain a certain seating depth. That's one of the main draws for looking at this 6BR-AI over the Dasher. My seating depth was always pretty tight.

 

[johara1]

This my point, either set it back or just shoot it...... Jim

 

[jamesdmock]

My reamer has .0125 freebore. I started out using the EPS bullets (107 grain) with about .0012 jump, and shot about 800 rounds through the barrel last year. The 105 hybrid has been used since this spring with .0025 jump. There is 1140 rounds through the barrel now and I have not had to change seating depth on the hybrid yet. I'm either not getting much throat erosion or the bullet doesn't care how much jump it is getting into the lands. Shot a clean with a good X-count on Monday night at 600 yards. One of these days I should measure it and see how much it has moved.

Maybe you should check your placement of the decimal? .0125 or .125; .0012 or .012; .0025 or .025? I often make these type "typo" mistakes myself. Good shooting.....James

 

[Alex Wheeler]

I had a barrel that didn't want me to chase the lands. Most do want you to chase the lands.

 

[BT1]

I still find it remarkable that a 0.002" difference in seating depth would make that much difference. Used to be mostly jumping in a range of .010 to .020 and was mostly happy with the results. Now with this recent 6brai barrel when you find your best load by jamming as an example .002 to .006. Seating depth is very critical. At 1000 yard group testing even .001" made a difference. Now I run +/- 0.002 difference seating tests even with my 284 barrels that usually like jumped about .020. In one case found that 0.018 proved even better. Seating depth has been discussed by many of top rated shooters as being one of the MOST important variables in loading. I now believe it is, as if not, more important that powder charge. Now loading powder at about +/- .01gn. I now DO chance the lands in all Barrels.

 

[BoydAllen]

For some situations, when using a powder that does not seem to need a lot of neck tension, soft seating can be a viable alternative. (Soft seating is a term used to describe loading longer than the throat length will allow so that the bullet is seated to its final position by the round being chambered, as the bolt is closed.) If one can find a charge weight that works with this sort of seating, staying up with throat wear becomes simpler.

 

[seymour fish]

For some situations, when using a powder that does not seem to need a lot of neck tension, soft seating can be a viable alternative. (Soft seating is a term used to describe loading longer than the throat length will allow so that the bullet is seated to its final position by the round being chambered, as the bolt is closed.) If one can find a charge weight that works with this sort of seating, staying up with throat wear becomes simpler.

Boyd, given your set of parameters re:soft seating, would you tip in a bit extra powder to maintain tune as erosion occurs and boiler room is expanded ? Seymour

 

[BoydAllen]

I think that that would have to be determined by experiment. IMO it is all too common for shooters to view loads as if they were somehow fixed points of geography. My understanding is that they are much more variable, depending on multiple elements. Sports or shooting situations that preclude on site, real time load adjustments also require good forecasting skills as to conditions that ammo will be shot in, and load development in similar conditions. Another approach is to load several variations and make a selection based on sighter target experience.

 

[swd]

What kind of case length do you end up with after fire forming? Any case shrinkage?

Edit I found it. 1.555"

 

[maddysdad]

saw groups shot out of jim ohara`s gun the other day.some as small in the ones.i see that this case may give the ppc at the 200 and 300 yards a run for its money.with the 80 grain and the heavyer bullets its unreal.it woud make t j Jackson smile.
gary b

 

[Terry Altom]

Having a reamer reground for 6BR-AI. Does anyone see a problem with any of these number while there's still time to change?

I need to add that my intention is to have it made for 80gn bullets and have the chambers throated as needed for the 103 and up ones. Also, if Harrells doesn't have a sizing die that fits, I'll most likely have a Whidden custom made for it. The seater will we a Wilson, blank or 6BR made with the reamer.


Thanks much,
Terry

 

[Alex Wheeler]

Having a reamer reground for 6BR-AI. Does anyone see a problem with any of these number while there's still time to change?

Thanks much,
Terry

Make the shoulder 460 or you will have a lot of sizing with off the shelf dies. .060 is a little short, may still keep the 105s above the doughnut but they will be down there.

 

[Terry Altom]

Make the shoulder 460 or you will have a lot of sizing with off the shelf dies. .060 is a little short, may still keep the 105s above the doughnut but they will be down there.

Any idea if Harrells has a Dasher or BRDX to fit anything larger than .460 at the shoulder? I have a die from them for my 30BR and like it very well.