quote:

Originally posted by 6.5BR:
Knew a person who had an AI, said it equalled a 25-06, but heck, if you are going to use a long action anyway, I don't know what advantage you have in the Bob AI, vs '06 version. Less powder and blast, but no case forming issues and factory ammo would make me personally look at the 25-06 first.

I do know he loaded HOT, and likely achieved speeds with high pressure loads, which safety was there in his rifle, last I knew.....but why push something past limits it should be? That is my thinking.

Me, heck, I'd be happy with a 'lil 250 savage' and THAT 25 would interest me in an AI version! But, within moderate distances, the standard '3000' would satisfy me I do believe.

If I wanted something to reach out there, I'd grab a 25/06 or 257 weatherby if I wanted a quarterbore to do it.

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my .257AI doesn't equal the 25/06, it beats it and on less powder

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Can a cartridge with a smaller case capacity "beat" a cartridge with a larger capacity unless it is loaded to a higher pressure? (all other variables being equal, of course)

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Originally posted by Leftoverdj:
I would not claim that the .257AI beats the .25-06, but it comes awfully close to matching it. There are limits to how much powder you can squirt down a barrel. The .257AI is close enough to those limits that it takes a good bit more powder to get a slight increase.

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Originally posted by olarmy:
Don: you could be right! So I just measured the difference in water capacity between 25/06 brass, and my fire formed 257AI (40 degree shoulder brass). The difference is "only" 9%.

Don't think that differential changes my hypothesis, but thanks for asking in a gentlemanly manner!

quote:

Originally posted by olarmy:

quote:

my .257AI doesn't equal the 25/06, it beats it and on less powder

Can a cartridge with a smaller case capacity "beat" a cartridge with a larger capacity unless it is loaded to a higher pressure? (all other variables being equal, of course)

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Originally posted by olarmy:
stepchild: interesting. I'm curious about the polygon rifling. I went to the Shilen website and didn't see any reference to it. They do mention "ratchet rifled" barrels, but don't say much about their advantages/disadvantages. Do you know if that is the same thing? Do you know if other barrel makers make polygon rifled barrels? thanks.

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Originally posted by ramrod340:
I will never argue with anyones claimed velocities for their AIs or any other case. I wasn't there.

What I will say is for a number of years in my youth I played with the various AIs, wildcats and then my own designs. Many were tested with the same barrels before and after along with strain guage pressures.

What I found over and over again is at the SAME PRESSURE you will gain around 1% velocity for each 4% increase in powder in an 06 based case. The 308 based a little less the more tapered 7x57 based a little more. Yes there are some huge jumps in the 257AI mainly because the parent is loaded to low 50,000 and the AI to 65,000+. Load both to the same pressure the gain will be along 1 to 4.

Can a given 257AI give a velocity more than another rifle in 25-06. Sure. Can a 257AI loaded to the same pressure beat a 25-06 in the SAME rifle barrel. No. Case capacity and more powder will win every time.

What I found over and over was the AI case hides pressure. People take their old loads or factory ammo then compare it to a new tight chambered AI that they load to 70,000+ and say look at my gain.

I seem to be of the limited school of if the parent pressure is 65,000 then the AI should be too. Yes I will use 65,000 for the 257AI because the 6mm rem has that pressure as max. Just because a tight chambered AI allows me to load to 75,000 doesn't mean I care too. I found if I cut a tight factory chamber to match the brass I intend to use I can load the factory case to basically the same pressure as the AI before I see signs. I simply choose to load everything I shoot to 65,000 or less.

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Incidentally Speer showed a velocity of 3,410 with a 22" barrel in their test rifle. They used 57gr. of N205 with 100gr. bullet and so did I until I ran out. MRP showed the same velocities, as it should have, it was the N205 replacement.

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Originally posted by olarmy:
According to RCBS, the case capacity of the 257AI is 59.8 while the 25/06 is 66.1. That's more than a 10% difference.

I got my first 25/06 in 1963 and a 257AI has been my go-to deer rifle for the last 20 years. I love both rounds.

olarmy,
It's all about efficiancy. Parker Ackley gives several examples in his "Handbook for Shooters and Reloaders"
Every bore size has a maximum powder charge that it can digest, after that it becomes barrel erosion! A good example of this is the 6mm/06 vs. 6mm Remington. The 6/mm Remington gives up what? 200fps in exchange for 10-20 gr.more powder. This wasn't posted to piss off the 6mm/06(or the .240 weatherby) people out there, just to make a point. There are many more examples to be shown right up to and including the WSSM line. My thoughts are: If it ain't broke, Don't fix it. The 30/06 comes to mind, think about it! 100+ years old and still going strong, I feel the magnums were invented to cover up the short comings of the average deer hunter's abilities and to sell more rifles. But as we all know, it's bullet placement that wins the game.


Stepchild

But, IMO, unless there is something really unusual about a particular rifle/load (fast barrel, high pressure, etc.), it's not prudent to assume that a case with 10% less capacity will "beat" a case with 10% more capacity.

Yes, you can match 25/06 FACTORY ballistics with a 257AI. But on the average gun, loaded to equal pressures, the 25/06 will will the velocity race.

Now, whether an extra 75fps or so is significant, is each individual's decision.