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270 Winchester Ackley Improved Load Data

 
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  #8  
Old 01-13-2011, 11:51 PM
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Re: 270 Winchester Ackley Improved Load Data

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Originally Posted by Catfish View Post
Ackley says it is not worth doing there for there is no data for it in his book. I can tell you that the 270 Win. has a case capicity of 4.36 cc and that the improved has a case capicity of 4.4 cc. With a difference of only .04 cc you are talking about an increase in powder charge to equal the same presure would be .1 gr at max. That siad the 270 is a very good round in it`s own right and if you have a custom rifle it`s probly a good shooter, besides that your probly the only one on your block that has one.
My 270 ai holds @ 6 gr. more powder than a win case 270. RPeter's 270 cases are even lesser volume.

a 270 win case is very compressed load with 62 grains I mean I long drop tube with small grain IMR 7828 sc clear to the top of the case and smash the bullet in. My ai can take 4 more grains be and below the top.

The AI has a straighter case and blown out forward shoulders with I think a 40 degree shoulder angle. I had to fire form a couple of cases and send them to RCBS to make custom dies.



PO Ackleys book kind of sucks. I have it and it is very old school.. You have to consider that it was written about 40 some years ago and they did not have modern slow burning powders and long high quality barrels
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.270 Ackley improved 29 inch 1.250 dia. target barrel 7mm STW 28 inch 1.250 target barrel. I also love my .458 mag for varmints and the biggest game in the world.

Last edited by budlight; 01-14-2011 at 08:42 AM.
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  #9  
Old 01-30-2012, 09:48 PM
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Re: 270 Winchester Ackley Improved Load Data

Wanted to add my 2 cents in here. With the loads you've quoted, you won't get enough difference by "improving" your case to make it worthwhile. I've built and shot a lot of wildcats over the years and some are great, others will actually perform no better and in some cases worse than the parent cartridge. You mentioned the 280 improved as a case in point, but with it, you only bump up your velocity 50 to 75fps with 150gr, bullets...in my opinion not worth the extra powder or cost to rechamber. Can you get higher velocity improving your 270? Yes...but, you will be way over safe pressure limits if you do so, so tread cautiously. I've seen too many rifles blown up to recommend a green light for you on this. Good luck
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  #10  
Old 01-30-2012, 11:31 PM
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Re: 270 Winchester Ackley Improved Load Data

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Originally Posted by archeratlrg View Post
Can you get higher velocity improving your 270? Yes...but, you will be way over safe pressure limits if you do so, so tread cautiously. I've seen too many rifles blown up to recommend a green light for you on this. Good luck
I guess you don't understand reloading, powder burn rates, and case size effect on pressure. You could say run 60k pressure in a 30-06, a 300 win mag, 300 Ultra mag, 30-378 Weatherby One case has a max of 60 grains and the biggest 120 grains of powder. The peak pressure is the same the difference is slow burning powder can give a higher average pressure for the full length of the barrel. Even make use of longer barrels

I will agree that very little is gained with additional powder in short barrel rifles. That is why my barrels are at least 28 -34 inches long

I personally have never seen a blown up gun.
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.270 Ackley improved 29 inch 1.250 dia. target barrel 7mm STW 28 inch 1.250 target barrel. I also love my .458 mag for varmints and the biggest game in the world.
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  #11  
Old 02-01-2012, 07:29 AM
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Re: 270 Winchester Ackley Improved Load Data

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Originally Posted by Big Jake Duke View Post
What I can't understand is how badly the 270 improved is trashed, by people who don't own them, and the 280 AI is lauded.

They should be nearly identical. The 270 win has had a slight edge over the 280 with 140gr. The increase in performance according to some sources by making a 270 improved is 7.8%, the 280's improvement in performance is rated at 7.7%.

So how can one be a piece of crap and the other the best thing since sliced bread?
LL! That's OK, I like it when people thrashes the idea of transitioning to .270AI because I am in the process of acquiring parts for a .270 AI build. Cheers!
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  #12  
Old 08-16-2013, 06:57 AM
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Re: 270 Winchester Ackley Improved Load Data

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Originally Posted by FEENIX View Post
LL! That's OK, I like it when people thrashes the idea of transitioning to .270AI because I am in the process of acquiring parts for a .270 AI build. Cheers!

He wasn't thrashing the 270AI - He was thrashing people that say the 280 AI is good and the 270 AI bad.
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  #13  
Old 08-16-2013, 02:34 PM
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Re: 270 Winchester Ackley Improved Load Data

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Originally Posted by Long Time Reader View Post
He wasn't thrashing the 270AI - He was thrashing people that say the 280 AI is good and the 270 AI bad.
That's what I said ...
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  #14  
Old 08-16-2013, 09:51 PM
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Re: 270 Winchester Ackley Improved Load Data

I have a 270 Sherman which is a blown out, lengthened and improved 270win. It holds about 10% more powder than a regular 270. I currently use 64gof RL22 with a 130g Berger which is 10% over the max listed for RL22.

If I understand correctly a 270 AI has about 5-7% more capacity than the 270 Win and would likely have powder charges around that much heavier than the 270WIN.So you could work up loads up to 7% over book loads for the 270 and be in the ballpark(start that much lower also and work up).
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