Shootist43Let me begin by saying that I love the 6.5 x 55 Swedish Mauser (the original 1896 version.) Including the Swedes I have given to my grandchildren or plan to give them, there are just over a dozen of them in my safes. In order to reply to this question I went online to find out what the Ackley version of this fine old cartridge would do. In short 2900 fps with a 140 gr. bullet. My current load of 46.5 gr. of 4350 and a 140 gr. bullet is 2775 fps. To me the 4.5% increase in velocity isn't worth the trouble. If for some reason you really wanted to stick to the 6.5 caliber there are a number of options that would yield a greater boost in velocity like the 6.5 Creedmoor or the 6.5 x 284.
I am unsure about any great ballistic advantage to the Ackley cartridges. However, I am quite sure that some of them provide for more positive and consistent headspacing in some rounds. Plus, for marketing purposes, I guess adding the "Ackley Improved" suffix accounts for something.
I would not trust any of the Ackley published loads, even though ballistically they always look impressive. He did not use pressure equipment during his load development- he used the "something just short of action failure" method.
Bruce22/250/250 savage will give a gain, as will 257 Roberts/7x57, and 6.5 swede, as the original cases are so tapered.
ackleying the 308 family is virtually a waste of time due to min body taper.
the 30/06 case in more like the 308 family.
375 h&h will give a gain, but do you need it in that situation?
as bob says, ackley data needs to be treated with respect for the reasons he said, but also because some powders have changed burning rate since then.
I thought I would like a 280 ackley, but have come to the conclusion I will stick to the std 280, as I have custom dies for my chamber and life is good.
I couldn't agree more Bruce but with modern new brass all cases should have the same strength and temper.bob, we tend to think in terms of case capacity, but brass strength and temper also have a lot to do with acceptable pressures.
Thank you for posting there are some interesting and valid comments.As was said above, thanks to all who took the time to reply. Your comments are really appreciated and more helpful than you could imagine.
Again, thank you!
@CBHThank you for posting there are some interesting and valid comments.
I might considering the .280ai, I note Bruce Moulds comments but as he says he already has the gear so there is no need to change I would be starting from scratch so if there is a gain to be had the time to do it is on the first build
in the black powder world, Bertram does not have a good name, for consistency or reliability.
do not go by an annealing mark.
it gives no guide to temp or time.
people started looking at that when lapua brass presented with annealing marks.
win, rem etc brass without the mark has also been annealed, but has the added process of a final polishing to remove the mark.
in actual fact the term annealing is a false one when applied to cartridge cases.
true annealing makes brass as soft as plasticine, so we partially anneal cases, more at the neck than the base.
norma brass used to be softer in the base than rem or win, and hence primer pockets opened up at less pressure.
you really need to partially anneal necks each shot or two to maintain consistent neck tension and maximize case life.
some of the most consistent and best brass I ever had was lake city match 30/06 brass.
I used it for 25/06, 6.5/06, 270, 30/06, and 35 whelen.
@ Bruce mouldsbob, we tend to think in terms of case capacity, but brass strength and temper also have a lot to do with acceptable pressures.