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.270 Win Ackley Improved?

 
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  #1  
Old 03-13-2008, 01:09 PM
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.270 Win Ackley Improved?

I'm considering building a custom, med-long range (750 yards max) whitetail / mule deer / antelope rig.

There's only one big requirement: It has to be able to shoot some type of factory loaded ammo that you're able to pick up at any hardware store in Backwater City, USA.

This didn't happened to me, but a friend drove to Pennsylvania for a deer hunt only to discover that during packing his ammo can had been left at home. Do you know how hard it is to find 6.5x284 ammunition at the local stores in northern PA?

Does anybody here shoot (or have a ballistic program) that could provide info on what kind of velocity to expect from Richard's 169.5gr & 195gr or Berger's 150gr? 26" barrel and a chamber loose enough that you don't have to neck turn your brass.

And would I have to cut the throat long to accomodate the longer bullets, or is the ogive radius shallow enough to be able to use a standard throat?

As far as choice of caliber: .270AI .30-06AI 7mm Rem Mag .300 Win Mag are about the only ones I could think of that you could be sure to find.

O.K. Let me have it now. I'm a big boy, I can take it.
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Old 03-13-2008, 02:23 PM
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Vote non wildcat

If you do an AI round you are not only going to be shooting different ammo but the velocity will be further decresed by the larger chamber. You will have trouble shooting that at long range because your traj will be much altered. At least with the 7mm Rem mag, you could sight in with both your handloads and a factory load that you think you could find. If the bullet and velocity are the same, you only have do deal with any difference in point of impact...which is easy to deal with in a quick sight in. Of course you could sight in with factory ammo out of the 270AI or 30-06AI. But do you really want to deal with two traj that much different at long range? Guess you could load 270AI down to what the factory 270 would give in an AI chamber, but you might be left with a pop gun.

The 7RM is as good as any for what you said you want to shoot. That would be my vote.

V911

Last edited by Varminator 911; 03-13-2008 at 02:37 PM. Reason: ellaborate
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Old 03-13-2008, 02:39 PM
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And let's further assume...

...that if you did have to switch to factory ammunition you'd reduce your range maximums to the appropriate level for the energy levels that they would generate.

Obviously if all you can find at the local hardware store is Federal Powershok 150gr Round Nose Soft Points (generating about 1166 ft./lbs. @ 300 yards), your effective range has been reduced by quite a bit.

Varminator 911 - Another good point. How much velocity do you lose shooting factory ammunition out of an ackley chamber? Would a 26" barrel and an ackley chamber be similar to a 24" barrel and factory chamber?
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Old 03-13-2008, 02:54 PM
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Don't know on velocity

OK say you get somewhere and you use ammo with different bullet or velocity. You don't then know the trajectory. How are you going to shoot that very far? How are you even going to shoot it past 300yds even after a quick sight in?

I have no experience with factory ammo in an AI chamber. Seems to me that the loss would be proportional to the difference in case capacity. Probably 100-200 fps or more. And factory ammo is often below advertised. So you might well be 200-400 fps below good handloads in 270AI for example.

I'd never build a custom gun in an AI chamber and saddle myself with such restictions. But that's just me. In 7mm RM you could make up a pretty good load to match at least one factory load. Same bullet same velocity. That's workable to me.

V911
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Old 03-13-2008, 03:29 PM
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V 911 -

So I design the rifle around the 7mm Rem Mag and a handload for the 162gr Amax or the 168gr Bergers. If I had to settle for a factory load of 140gr or 160gr Partition/Accubond, I'm still in good shape. Good thinking!

I'm just thinking worst case scenario; if your rifles arrive at the airport but your clothes and ammo don't, you can always buy new camo and ammunition at the local Wal-Mart.

This would probably change the parameters of the hunt from a long range hunt to a 300-350 yard max. (and obviously you would have to verify point of impact / bullet drop for the new load), but at least you're still hunting.

I was just trying to take advantage of the popularity of the big three?/five? (.270 .30-06 .308 .300 Win Mag 7mm Rem Mag) and the availability of factory ammunition, while trying to wring the most performance I could.

Anybody else?
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  #6  
Old 03-13-2008, 03:53 PM
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Like your load

The 7 RM with 162 Amax or 168 Berger is about as good as it gets in a carry weight gun for deer to 800 yds.

I'm still concerned if you switch to factory loads. While I'm not familiar with what is offered, you are probably looking at 140/160 Accubond or a partition. Even if you sight in with that load, you won't know the velocity. That still leaves you guessing at the trajectory past 300 yds. But at least with the 7RM you'll have a better guess than with an AI chamber. And a lot more fire power to boot.

Good luck with this project!!!

V911
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