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Thread: Ballistic Effeciency: Does anyone care?

  1. #1

    Ballistic Effeciency: Does anyone care?

    I am a middle aged shooter who had run the gauntlet of factory cartridges, wildcat cartridges, Improved cartidges, and odd ball obsolete cartidges in my shooting career. One of the criteria for what constitutes a 'good' cartridge that I have gravitated to, is its "effeciency": In this definition, the ability to effectively utilize its given powder supply.

    I frequent a few stalking and vaminting sites based outside the US and I am amazed to see all the folks who want bigger case capacities. Making "Ackley Improved" rifles is far more popular here, let's say, than in the US. To me it's odd that, in a country where powder is so expensive, people would want to pour in even more for what might be dubious gains.

    I always seem to raise the hackles of the Ackley Improved shooters when I talk about this subject and they retort by telling me how fast they can drive a certain bullet from their Eargersplittinloundinboomer Ackley Improved. I'm not interested. What would be nice is a discussion as to how shooters view the subjset of cartridge effeciency, or if they'd even given is much thought.

    Any ideas to share? ~Muir

  2. #2
    Methinks another very large can, nay bucket of worms Muir, I'll kick off with the short mags, supposedly a better powder column for a more efficient burn? I have the 7mm WSM.

  3. #3
    Hello Muir

    I guess I will stick my head above the parapit

    I have 3 AI rifles, a 250, a switch barrel in cal .257 & .280 and a 7.08, and yes all very close calibres.

    I had my first AI (the 250) built because of a write up by Steve Timm in April 96 Varmint Hunter.

    I was so impressed by the rifle and how it performed I had to have one.
    I did not achieve the same ballistics as Mr Timm but he used a 22" barrel and I a 19" barrel. With a 100gr bullet he was running 3100fps and mine was running 2874fps, not stunning speed from mine but great accuracy.

    The other Ackley Improved rifles came along because I got the Ackley bug and dont regret it at all.

    Its not about the extra case capacity because as we both know speed does not always equate to accuracy.

    I really like the 40 degree shoulder because for some reason not known to me I very rarely have to trim any of my ackley cases ,and if there is one thing I hate doing its trimming cases.

    My .250 I have had since 96 and fireformed 150 cases on day one.
    I am still reloading those same cases and they are 10 reloads minimum.

    I have culled a few, but only because the primer pockets became sloppy.
    I do cut the primer pocket on all my cases (even non ackley) every reload as that seems to be where the stretch is if any, plus it cleans the pocket nicely.

    I think Ackley is not for eveyone but I if you are going to have a custom rifle built it is definitely worth the thought, IMHA.

    Dave Tooley built all my Ackley's bar the .250 and they all shoot very accurately indeed.

    I seem to have run on like a dripping tap again



  4. #4
    Finn: A bucket? Perhaps, but it's a twisty subject and one that folks don't think much about. Much of shooting these days seems to be a popularity contest when some reasonable thinking might be a better course. My example from the days when I made a living building rifles for folks:

    A 280 Remington with a 140 grain bullet 57 grains of IMR 4831 gave me 2926 fps.

    A 7mm Remington Magnum, 140 grain bullet, same powder, 68 grains gave 3166 fps.

    For less than 10% more velocity it used it used 20% more powder. I doubt if the velocity difference would be noticed by a deern or in real world field trajectories in the field. ~Muir

  5. #5
    Max: A custom rifle is expected to shoot. Like you say, you're not shooting with velocities on the limit so for you it's a choice and I won't dispute that. But again, I can easilly clear 2800 fps with 100 grain bullets in my Remmy 257 Roberts using 47 grains of , again, IMR 4831. Less powder with other loads... and sometimes higher velocities. (4064 will clip 3000 fps)

    I run my cases over a Lee trimmer stud at every reloading. If it needs trimming it trims, if not it doesn't. Beats measuring all my cases! Now that's an activity I despise! ~Muir

  6. #6
    Once in a while an improved Earsplittenloudenboomer allows us to find an accuracy node at a velocity not available to standard cases.
    Granted most of us velocity freaks just like something a little different but then if we were to demonise improved cases then we also have to start culling 'overbore' cases and get rid of 25/06 because it is not as powder efficient as it's smaller siblings ie Roberts, 6.5-284 would be right out since it's lifespan is only 1k rounds etc.
    I think we do weigh up efficiency and then add pride of ownership of something different less run of the mill and come up with a mental level of acceptance. A few of us would fancy the idea of a 6.5-375 doing 5000+fps but few of us would accept replacing a barrell every 150 rounds.
    So to answer the question, Yes we do consider powder efficiency, but it is not the be all and end all of considerations when we spec' a new rifle or have a new chamber reamer made.

  7. #7
    After 30 years association with Ackley IMP cartridges I can't be convinced as to their ballistic superiority to their parent cartridge but that's a different tale. Accuracy sweet spots can be found all through velocity ranges as long as bullet stability isn't compromised.

    You can argue Ackley this or that all day, but what about the person buying a rifle off of the shelf? Is the 25-06 really what is needed or is a 257 Roberts going to do the job, for practical purposes, as well? Less powder, very close ballistics... yet people are quick to jump to the larger case because it is more "powerful". If you can get within 5% of the ballistic capability of a cartridge using 10% less powder isn't that worth it? Does the prospective buyer look twice at the 30-06 when handed a 300 Win Mag?

    Us Velocity Freaks?? Brother! You have no idea! I used to have folks claim that someday, I'd open the bolt and have nothing to show but a bore plated with molten brass! I've been there and done that several times over. ~Muir

  8. #8
    The bottom of the pail is already covered

  9. #9
    Yeah. Maybe this was a bad idea. ~Muir

  10. #10
    Not wanting to change direction with this thread, but while we are at it what if any improvement in ballistics have been experienced with Moly coating? would you have any thoughts on this Muir? (have'nt used the stuff myself)

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