Reloading Ackley vs standard cartridges

[Texas Pride]

The following could apply to any cartridge and its Ackley counterpart, but I'm especially interested in the .280 Rem chambering:

So I've been looking at the .280 Remington lately, since I like the .270 Win but already handload for the 7mm Rem Mag (same bullets). Whether the Ackley Improved version of the cartridge is worth the expense is debated on several threads of several forums, so I looked up the data for each on Hodgdon's Reloading Data Center. Hodgdon shows marked gains in velocity with the Ackley chambering, but it's not really a fair comparison: they limit the standard chambering to 58,300 PSI, but load the Ackley version to 62,200 PSI. They also use slower powders in the Ackley not shown for the standard .280.

My questions: does this mean that one could load a standard .280 to the Ackley pressures since the Ackley is made simply by reaming out a standard rifle chamber? Is there any reason that a pressure which is safe in an Ackley would not be safe in a standard? Is the reason for the slower powders in the Ackley just a matter of a sharper shoulder angle, or could one use the same powders in either? This is just theoretical at this point, I don't own a .280 yet and wouldn't make a potentially unsafe load without more than internet feedback, but I wanted to see if anyone had some insight as to what's going on here.

 

[steve4102]

My questions: does this mean that one could load a standard .280 to the Ackley pressures since the Ackley is made simply by reaming out a standard rifle chamber?

Depends on the rifle. The 30-06-280-270 are all based off the same 30-06 case, but they run at different pressures. WHY? Cuz there are old and weak actioned rifles chambered in 30-06 and 280, but not so in the 270. So, the 270 gets the higher safety pressure rating or 65K. What does it mean, it means that if you have a modern bolt action rifle like the Rem 700, Win M-70 etc, then there is no reason you cannot safely load your 280, 280 AI or 30-06 to 270 pressures.

Problem is, without tested data or actual pressure testing equipment, how would you know you are at 60k, 62K or even 65K?

 

[Texas Pride]

Thanks for the reply. That does make sense. Weak loads for old rifles is a common occurrence, and one that makes sense here. Is that the only hypothesis? I'm no stranger to loading older cartridges to higher pressures for use only in modern, strong actions.

Problem is, without tested data or actual pressure testing equipment, how would you know you are at 60k, 62K or even 65K?

Agreed. In this case, loads are given along with their tested pressures, but without some major testing equipment (I can barely afford range fees, much less my own lab) creating new loads above the published ones would be dangerous. But loading the .280 with existing higher-pressure loads seems rather straight-forward.

 

[Stack]

Maybe you work a load up very slowly on a chrono stopping at the Ackley velocity (should you get there) and check your brass with each shot. Does the Ackley have a longer throat than the 280? This can have a great deal to do with how much pressure a particular loading generates on it's way to a given velocity. Don't be too disappointed if you don't get quite there before signs of higher pressures begin to appear. Just call it good enough. Just be careful! There's my .02

 

[NCsmitty]

Not that you need a reason to get another caliber rifle, but why would you want a 280 Ackley when you have a 7mm Remag in the stable?

And yes, as long as you know that you are achieving that 62K pressure in a quality rifle designed for it, it is possible to push the envelope.



NCsmitty

 

[Texas Pride]

Not that you need a reason to get another caliber rifle, but why would you want a 280 Ackley when you have a 7mm Remag in the stable?

Yeah it's definitely more of a want than a need. I do have a softspot for calibers that most folks aren't familiar with (I recently had a friend argue with me that there's no such thing as a .41 magnum and so my revolver must be a .44mag. Fun times). I've taken plenty of whitetail with the 7mag (700 CDL, lefthanded) and never once had a chance to using my tracking skills. However, I'm still attracted to this cartridge using the same 140 grain .284 bullet, without a case belt (annoying when the brass swells in front of the belt and won't chamber easily), pushing 3k fps with less powder than the 7mag needs to do the same. I love the the 7mag for longrange target shooting, where its strength really helps heave those heavier bullets out there. But unless I go up north to hunt elk or moose, a .280 would do everything my existing rifle does with less powder consumption and an extra round in the magazine (read: an extra pig in my freezer). It would be a deer-and-lighter gun for me. Anything bigger gets the 7mmRM.

I could hunt with my 7mag for the rest of my life and be perfectly happy, but I just see the .280 as slightly more my style. My next rifle will either be a .280 or a .338-06. I haven't finished inventing all the reasons I want/need the .338 yet. I'm considering the improved versions of both, but only if there's a real benefit.

 

[Texas Pride]

Maybe you work a load up very slowly on a chrono stopping at the Ackley velocity (should you get there) and check your brass with each shot. Does the Ackley have a longer throat than the 280?

Sound advice. I'm not sure about the throat length, but that's a great point. If I remember right, that's why the 6.8 SPC II chambers can handle the hotter loads, because they lengthened the throat to give the powder more room to expand before the bullet gets caught up in the rifling. If I end up doing this, I'll be sure to talk to my gunsmith about it.