308 Ackley Improved

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bearhunter338-06

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Has anyone had there rifle cambered to the 308AI. Looking at the diferance between a 308 win and the 30-06, I was thinking if you had a 308AI, it would match or even edge out the 30-06.

Can anyone give me any info as to my thinking being correct.
 
I looked into a 308AI a few yrs ago and figured out that the gains were minimal and not worth the effort.

The 300WSM would be a MUCH better idea for increased velocity in a short action 30cal.


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Nothing beats cubic inches!

The 30-06 has more case volume than the 308 - even an improved version - and can never match the 30-06 when both are loaded to the same pressure.
 
'Boo said:
Nothing beats cubic inches!

The 30-06 has more case volume than the 308 - even an improved version - and can never match the 30-06 when both are loaded to the same pressure.
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Kinda like the .338-06 and the .338WM...:D
 
blargon said:
Kinda like the .338-06 and the .338WM...:D
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I never claimed any different. With most loads the 338-06 will be 75 - 100 fps slower than the 338 Win. in rifles with the same barrel length. The question if that bit of velocity gain is worth it is up to the shooter.

The same can be said for the 308. No animal in the world will know if it was a 308 or a 30-06 that launched the bullet that killed it.
 
I'd much prefer a 30-284 (which is just a 7.5x55 clone), or just do up a 7.5x55 and make use of readily available and inexpensive dies and brass.
 
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'Boo said:
I never claimed any different. With most loads the 338-06 will be 75 - 100 fps slower than the 338 Win. in rifles with the same barrel length. The question if that bit of velocity gain is worth it is up to the shooter.

The same can be said for the 308. No animal in the world will know if it was a 308 or a 30-06 that launched the bullet that killed it.
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You may find that this does not hold up if you load heavy for caliber bullets, or long mono-metal bullets. If the rounds are loaded short enough to feed through a magazine, the .338/06 loaded with a long bullet looses much more powder volume than does the .338 Winchester. Heavy bullets are most often combined with heavy charges of slow burning powder which use up lots of powder space. Under such circumstances the difference in velocity between the two cartridges could be well over 100 fps, depending on the nuances of each rifle.
 
Boomer said:
You may find that this does not hold up if you load heavy for caliber bullets, or long mono-metal bullets. If the rounds are loaded short enough to feed through a magazine, the .338/06 loaded with a long bullet looses much more powder volume than does the .338 Winchester. Heavy bullets are most often combined with heavy charges of slow burning powder which use up lots of powder space. Under such circumstances the difference in velocity between the two cartridges could be well over 100 fps, depending on the nuances of each rifle.
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???

Please explain. Would they not both lose exactly the same amount of powder if they have the same loaded OAL as their case lengths are essentially the same (within a few thou)? The smaller case (338-06) would lose a higher % of powder as the bullet is seated deeper, but the amount (in grs) would be the same as for the 338 WM. This situation would hold for every bullet weight and loaded OAL would it not?

The gap in MV for the heavier bullets has to do with the need to use progessively larger amounts of slower powder to get max MV at the same pressures, and the smaller case runs out of space to take advantage of the slower powders sooner than the larger case.

IMO.
 
I know a 338 Winchester will easily launch 200 grain bullets at about the 3100 fps mark. I doubt the 338/06 will do 2900 at similar pressures. The 338/06 (which I consider to be a pretty good cartridge BTW) is one of those whose owners load to the nuts to try and equal the 338 Win. It won't. It won't really even come that close unless loaded way too hot. I have loaded 250's to 2600 fps in my 35 Whelen but that's actually too hot. Even so, it won't come close to matching the 358 Norma which will easily do 2750 or better at reasonable pressures. The relationship between the Whelen and Norma is similar to that of the 338/06 and 338 Win Mag.
To the subject of the original post; a 308 winchester, rechambered to 308 AI will probably gain about 1/2 of one percent. That would amount to about 14 fps with the typical 150 grain load. The only real change is in the shoulder angle and the change in volume is minimal. There is no magic in a shoulder angle. Regards, Bill
 
Andy said:
???

Please explain. Would they not both lose exactly the same amount of powder if they have the same loaded OAL as their case lengths are essentially the same (within a few thou)? The smaller case (338-06) would lose a higher % of powder as the bullet is seated deeper, but the amount (in grs) would be the same as for the 338 WM. This situation would hold for every bullet weight and loaded OAL would it not?

The gap in MV for the heavier bullets has to do with the need to use progessively larger amounts of slower powder to get max MV at the same pressures, and the smaller case runs out of space to take advantage of the slower powders sooner than the larger case.

IMO.
Click to expand...

Perhaps what he means is not so much grains of powder, but percentage of case capacity.
 
Andy said:
???

Please explain. Would they not both lose exactly the same amount of powder if they have the same loaded OAL as their case lengths are essentially the same (within a few thou)? The smaller case (338-06) would lose a higher % of powder as the bullet is seated deeper, but the amount (in grs) would be the same as for the 338 WM. This situation would hold for every bullet weight and loaded OAL would it not?

The gap in MV for the heavier bullets has to do with the need to use progessively larger amounts of slower powder to get max MV at the same pressures, and the smaller case runs out of space to take advantage of the slower powders sooner than the larger case.

IMO.
Click to expand...

A bullet of any given length will reduce the height of the powder column in each respective cartridge. If the choice of powder was the same in each cartridge, it might very well be that the .338/06 load would have to be compressed with even a lighter/shorter bullet, whereas the .338 Winchester load might not be compressed. When switching to a longer bullet which results in a compressed .338 Winchester load, it is unlikely that the .338/06 could match it. Going to a faster powder in the .338/06 might result in high pressure before the anticipated velocity is reached and the slow powder takes up so much room that you can't get enough powder into the case to get the anticipated velocity even though the pressure is low. Consider the disparity in velocity between the two cartridges when loaded with a 250 gr bullet and 4350. The Nosler manual suggests a difference of 280 fps, but the Speer manual is kinder suggesting a difference of 92 fps. Now, switch from a lead core bullet to a monometal bullet of equal weight and how does that impact the velocity of each cartridge? The .338 Winchester load would go from 99% load density to compressed, but the .338/06 load was already compressed at 104%, so either the bullet would be seated long or the powder charge must be dropped to prevent distortion of the case.

I first came across this with my short barrel .375 Ultra. When I began wortking up loads I had access to a .375 H&H for comparison. With light bullet weights, I could comfortably match the .375 H&H velocities from my short barrel. But when I began to load the very long 380 gr Rhinos, the difference between the Ultra and the H&H began to show. From basically even performance with bullet weights from 260-300 grs, when loading the long 380 gr Rhinos my Ultra jumped ahead by more than 120 fps.
 
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