Need Advice On 6mm Ackley Improved

[jackie schmidt]

I recently helped a good friend put together a 6mm Ackley Improved. I had a 1-8 twist 27 inch long Krieger laying around, he had a Farley Action, so we decided to build a barrel block gun.The idea is for a long range Live Varmint Rifle, out to 1000 yards, using what ever proves to be the most accurate 95+ grn high BC bullet.
We did not use a tight neck reamer, just a minimum spec Dave Kiff offerring. The cases form beautifully. Everything is working as it should.
Most of the sites I have gone to that feature this chambering are listing velocities in the low to mid 3200 range with a typical 105 grn bullet. Heck, back when I did the 6BR test with my RailGun, I worked up to 3000 fps with no problems with most 105 and107 grn bullets. Just 150 fps with darned near twice the powder seems a little skewed. I know we are working with diminishing returns, but not that diminishing.
What is the true upper load window, (velocity wise from a 27 inch tube), for this case in a Rifle that is assembled with all of the care of a Benchrest Rifle.. We had it at the range last week end, and worked up to 3400 with Reloader 19 and the 105 A-MAX, and everything looked good. Accuracy, though, was not what I was looking for. 1/2 to 5/8 inch 3-shot groups at 100 yards. It seems to me it should do better. I told Geramo that I think the Reloader 19 is a tad fast for this twist and the big long bullets.
Before we head to the range again, I thought I would touch base with some of you long range shooters. I really do not fool around with these types of chamberings enough to have a good feel for what should be happenning......jackie

 

[Dave Tooley]

Jackie

Most of us use RL22. You see 3200 FPS as the upper accuracy window. It seems that with all calibers, shooting heavy bullets at long range, that the further you are from 2900-3200 FPS the less accurate they are. Don't hesitate to go to another bullet if one doesn't show you something pretty quickly.

Dave

 

[JerrySharrett]

Jackie, on Quickload a 105g Berger BT and 53g Rl-22 in a 26 " barrel shows 3275 fps at 60,000 psi.
With a 90g Berger BT and 55.8 g RL-22 gives 3495 fps at 60,000 psi.
The heavy bullets in a 6mm really slow things down.
Like Tooley says over about 3200 and accuracy drops off.

 

[Andrew B]

I stopped working with a 6mm Ackley improved after realizing that while I could push a 105 gr bullet faster than 3200 fps, it seemed to not be worth it as the groups opened up. I am currently very happy with a 6x47 Lapua - getting 3100 with 105's with significantly less powder, plus can use Lapua brass, not available for a 6mm remington.

I also used RL22 and H4831 in my 6mm ackley. I am using RL19 in the 6x47.

Perhaps the new 108gr Bergers, that are not vld's, may work at the higher speeds. A flat trajectory is a beautiful thing in a PD gun. I think I will break out the Ackley and check it out. Am headed to the PD fields in May and July.

 

[J. Pendergraft]

I think Charles E. was getting very good accuracy north of 3300fps but using a longer barrel than 27". I can get 3200 from my little 6x44 w/ 30 inch barrel so why burn the extra powder and get shorter barrel life unless you want to get to that next higher accuracy window. IMO R19 is definitely too fast for shooting the heavier bullets if you are looking to maximize the velocity. Some bullets won't like the speed though.

 

[Charles E]

Jackie, just this once, I'll give data. Of course, you know to start below & work up, and so should anyone reading this post. These are warm loads, shot in a BAT action, & chamber throated out for 105-grain bullets.

Accuracy load: 47.5 grains H-4831-SC with a 106-grain Clinch River bullet. Won a lot of relays, & several screamers at 1K -- As I remember, a Screamer is less than 3.5 inches for 5-shot group; maybe it is less than 4 inches. Gave Phillip Yott a couple of great times, when he could come out & say "You shot a screamer, but you didn't win." 'Course I got a few wins out of it, too.

Speed load: 49 grains Reloader 22, same bullet. That hit 3,400 & won me a relay or two. This was one of the faster lots of Rel-22. Rel-22 was all over the map for a few years, always start low & work up.

I believe Cheechako uses the same 4831 load -- within half a grain, anyway.

P.S. This was a 30-inch long barrel, with a tensioning tube.

 

[jackie schmidt]

Thanks

Charles, I had a feeling that 4831 might be a great powder for this chambering.
I wish we had a longer tube, but I had this Unlimited Barrel at 27 inches, so we used what we had.
I will let you know how the next range session goes. This could be a real challenge.
I would like to see 1/2 to 5/8 groups at 200 yards with a 3300 fps velocity with the 105's. May be a tall order.........jackie

 

[tiny68]

6mm Ackley

Dave built me a 6mm Ackley last year. 27" Hart with a 1:9" twist. I am by all means still a beginner in this distance stuff. I have had good success with RE-22 (load data below). IMR 4895 gives some great groups, but the velocity versus charge is wierd. Maybe one of you pros can explain this. These ladders where shoot at 400 yds. I cannot understand how such a change in velocity can have such a little impact on group size or PIO. With the RE-22 at 3150 fps, I routinely shoot 0.3 MOA at 300 yds (5 shots). I shoot the 107s just as fast. I never had a gun perform like this. But I am a junior in the sport.

tiny

 

[1000yrd ringer]

6mm ackley imp

hey guys...i am brand new to benchrest shooting. I have just got a parubian mauser action that i am having rechambered in 6mm ackley imp. I am having a lilja barrel put on it but still need to get a stock and mounts and a scope. any advise for who or what brand to use. Also i am curious...can you buy
6mm ackley imp brass? I have also heard that you can buy 6mm Rem brass and fireform it to your chamber is that true? I would apreciate and help i can get. thanks

 

[eggman]

Ringer, yes you will have to fireform your brass. Following is a link to a web page featuring 243 AI and 6mm Ackley. This site I believe will link you to another page or two that will give you some info on loads and such. Read up on the 6mm AI as much as you can and ask questions. As far as scopes you can't go wrong with either of the two you mentioned and can be picked up quite reasonably used . Good luck.
http://www.angelfire.com/sd/6mmackley/
Rodney

 

[Bob Smeltzer]

I don,t know if you are set on the 105,s But my 6mm AI shoots great with the hor. 87 gr V max 3/8 in groups at 100 at 3660 with 53 gr rel 19

 

[Bob Smeltzer]

The reason I said that about the long bullets , I have the same barrel as you!

 

[Steve Nelson]

6mm AI

Hi Bob,
I am just starting to work up loads for my first 6mmAI. 27" 1:10 Benchmark Barrel. I want to use the 87VMax and have a supply of N160. 50.5 gr is yielding about 3600fps with formed cases. Cases are not quite full though-any problem there? Are you jumping/jamming the 87 for best results?
Thanks,
Steve in NC

 

[Bob Smeltzer]

I tried 1 up to 5 thou. from touching did not make a lot of differance, the charge was a lot diff. went from 3600 to 3750 with 3660 showing the best with no preasure. At 3750 a small crater on the primer no hard bolt lift but the groups opened a little

 

[tylerw02]

I hate to dig up an old thread but I'm working with my 6mm AI again after a year's hiatus.

Before I had tried the 87 V-Max with RL19 and had very erratic accuracy. One group would be ~1", then the next may be .5".

My rifle is a Rem 700, Basix trigger, 27" Shilen 1:8" bedded to an H-S stock with a Leupold 6.5-20x.

I tried 105 gr Lapua Scenars with exceptional accuracy, but they just never seemed to work so well on p'dogs. The explosive effect just wasn't there. But having the 105s with 4831SC and RL eliminated the notion there was a problem in my reloading process.

Have there been bad batches of RL19 getting out that may be causing this issue? I've just ordered 100 105 gr A-Maxes to try. I'm going to try to work a good RL22 load with it since I have about 8 lbs of the same lot laying around.

Jackie, did you ever reach your goal?