270 Ackley

[7.62 Gunner]

I've worked with 3 custom 280 Ackleys and have never got them as close to a 7 Mag/7PRC as many say they are capable with a 180. The Berger 270 170 VLD has about the same BC as the 7mm 180 Berger and I'm currently getting about 100fps more velocity in the 270AI than I've been able to get in a 280AI. If that holds true I would have better trajectory, velocity and equivalent energy out past 1,000 yards. It is actually matching up better to the 7 Mag and 7 PRC from a ballistic perspective. I understand there are less bullet options and its not common as the 280AI but it's a fun and interesting project that is delivering some surprising results so far. It also has the nostalgia and cool factor of the 270 that many appreciate.

Before I built my 6.5 saum I did quite a bit of pondering on a 6.5x280ai, turns out it had the same capacity as the saum so I went that direction.
For a 7mm I'm not even interested until the capacity gets into at least the low 80s

 

[Alibiiv]

There is something about the classic 270 but to my understanding, Ackley never officially made an improved 270 Win. With current powders and new high BC 270 bullets I decided I needed to see what it could do. I necked down a 280 Ackley brass and seated a 170 Berger in it for a reamer order. Alex Wheeler chambered a #4 Krieger 1:8 barrel onto a the Lone Peak Ti action then bedded it into an AG Composites stock. Decided to go bright with the cerakote to match the stock. I just finished barrel break in but initial load work looks promising. N560 reached 3075 before showing pressure and the accuracy looks good around 2940. I can share more load data as I finish tuning if there is interest
View attachment 462321

Hmmmmm....... this looks familiar???? I'm pretty sure I saw this on FB in the AI group??? I do not believe that there are two of these rifles in that photo. I do not know the reasoning behind a manufacturer picking up on this cartridge.

 

[Alibiiv]

What's your

 

[Mike Matteson]

Just look up the case volume of each and it will tell you which is the most inefficient and least number of rounds before barrel replacement in an attempt to gain just a few more FPS.

I'm a lifetime 270 win man and I had one rebarreled in 270 AI before 270 WSM came out. 270win based cases are or should I say were cheap and plentiful. I would tend to say that if you anneal and don't expand the primer pocket I have cases that might be over 10 reloading cycles. But who cares I have a thousand of them. My Weatherby 30-378 was maybe 2-3 reloads and the barrel lasted about 400 rounds.

I also think that 26 and up barrel lengths are just free ballistic HP and the ability to burn the slower cooler powders

On your 30-378 rifle. Ever try and only bump the shoulder back a .0001 or 2 and shooting that way? I would lose my cases in my 308NM in 2 to 3 firing. I changed to a 300WM neck sizing die,because trying to get a neck sizing die for the 308NM would have been a long time in coming. It didn't fully resize the neck of the 308NM case. Got thinking about it and like that the neck was fully resized. I felt the case chamber better and center in the chamber. It's been so long back. I don;'t think I had any problems chambering the cases. I figured it was because the belt set the clearance up, not the shoulder. My case separations went away. I would lose my case do to primer pocket getting to large in about 10 or so firing.
My 308NM isn't anything compared to that 30-378, but it's kind of on the same line being a belted mag case.
Something to think about. It may or not work you.

 

[budlight]

On your 30-378 rifle. Ever try and only bump the shoulder back a .0001 or 2 and shooting that way? I would lose my cases in my 308NM in 2 to 3 firing. I changed to a 300WM neck sizing die,because trying to get a neck sizing die for the 308NM would have been a long time in coming. It didn't fully resize the neck of the 308NM case. Got thinking about it and like that the neck was fully resized. I felt the case chamber better and center in the chamber. It's been so long back. I don;'t think I had any problems chambering the cases. I figured it was because the belt set the clearance up, not the shoulder. My case separations went away. I would lose my case do to primer pocket getting to large in about 10 or so firing.
My 308NM isn't anything compared to that 30-378, but it's kind of on the same line being a belted mag case.
Something to think about. It may or not work you.

The 30-378's real problem is 120 grains of powder pushing a 30 cal bullet. The rounded shoulders and heat would crack the necks or the belt would be leaking.

 

[Mike Matteson]

The 30-378's real problem is 120 grains of powder pushing a 30 cal bullet. The rounded shoulders and heat would crack the necks or the belt would be leaking.

Another question. Are you annealing your cases? I know that I was having problems with neck splitting back then, I only anneal one time. That stop that. I do realize that the 30-378 does hold a lot of power.
That's got to be a lot of expense in getting case for it. You might give a neck sizing die in sizing you cases. I would think it would be worth the try to see is if that cut down on the lost of case do to case separation.
You can do whatever you want. This only a suggestion. Those cases being somewhere from $3. to $5 each.
I have used this with all my belted case rifles. 264WM, 7mm, 308NM, and 338WM chambers.

 

[Alex Wheeler]

That range looks familiar

 

[Darryle]

That is a sexy rifle!

 

[Ruger77mag]

Barrel length is 24" to the end of the brake, so it's approximately 22.5" barrel. I worked up pressure ladders with the top 3 powders out of Quickloads, RL26, 7828SSC, and N560. Both 7828 and 560 showed potential with near identical velocities. RL26 was crazy fast but the ladder looked like a shotgun. I'm working on seating depth this week and then I'll tweak powder charge. Below is an example of the groups it's shooting during the final rounds of breakin with virgin brass. Haven't seen anything over 1 moa yet. View attachment 462380

Hi did you get a custom reamer?270/280ai? Thanks

 

[Mike Matteson]

Just look up the case volume of each and it will tell you which is the most inefficient and least number of rounds before barrel replacement in an attempt to gain just a few more FPS.

I'm a lifetime 270 win man and I had one rebarreled in 270 AI before 270 WSM came out. 270win based cases are or should I say were cheap and plentiful. I would tend to say that if you anneal and don't expand the primer pocket I have cases that might be over 10 reloading cycles. But who cares I have a thousand of them. My Weatherby 30-378 was maybe 2-3 reloads and the barrel lasted about 400 rounds.

I also think that 26 and up barrel lengths are just free ballistic HP and the ability to burn the slower cooler powders

Now I realize that there is a lot free bore in 30-378 and I understand about loosing case in 2-3 load. Every think about trying this. If possible extend your bullet out and close as possibe to the lands to fireform the case. After that only neck size the case about 2/3 of the neck. That kind of puts a donut in the neck. Again leave your bullet extended trying to reach the lands. Maybe a heavier gr bullet would be longer and reach the lands. To push the base tight to the bolt face. That should force the shoulder to move forward and not so much as the belt at the base of the case. Then only neck size the case, but only about 2/3 of the neck. I never tried FL sizing and stopping short of the shoulder or only bumping the shoulder a few ths or so. That should stop the base separation. With a neck sizing die it does create in the neck area donut, but at your chamber size.
I stumble over this over 25yrs ago. I use a 308NM rifle and chamber. I would loose my cases in 3 firing. I got a 300WM neck sizing die. That only sized about 2/3 of the neck. The 300WM is longer from base to shoulder than the 308NM. That did 2 things for me. It stoppd the case separation, and I got a little better grouping out of it. My brass life change from 2 -3 to no case separation. I load hot and about 5grs over manual heavy load for that rifle. I would loose my primer pocket in about 12 firings after that.
I would reduce my powder load to fireform that case, because you would be putting the bullet at or into the lands to start with.
I put a lot of work into those cases, mostly slow by hand working the cases. I would weight scale my cases, and cut the neck for thickness. At that time I only annealed one time. That did stop the necks from splitting. The old in the pan with water and nock over.
I have a couple of rifles that are belted, and I haven't work up any loads for them yet. I will put that I stated above into play.
Something to think about anyway.

 

[tomcat818]

Appears to be very efficient considering my 270 Win 22" barrel w/ 150gr over 56.6gr H4831-SC is running 100fps slower than your N560\170gr. N560 was even slower with 55.4gr 200fps slower than your results.