Issue with Acme 124g LRN C.O.L

Discussion in 'Ammunition and Reloading' started by forgetaboudit, May 29, 2017.

  1. forgetaboudit

    forgetaboudit New Member

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    Hello all,
    I've got an M9 and have been reloading for the last year without issues.
    I previously have been using Berry's 115g and HS-6 powder. I just bought a box of Acme 124g LRN non-coated bullets and a pound of Hodgon Titegroup and the book I use says for that combination the COL should be 1.169". When I set the bullet depth to that, it sits way out of the chamber, and gets stuck. I tried running it from the mag to the chamber by releasing slide, but it won't fully slide forward.
    I've tried increasing the seat until the round fits nice in the chamber and turns in it, but that COL is 1.058 or less.... Thats quite a difference in recommended and actual. Starting powder weight is 4g. I dont want to shoot the short COL and starting load without speaking with someone that may know if I can lower the charge, or just use different bullets.
    I'd hate to have bought them, and they don't work...
     
  2. HumbleMarksman

    HumbleMarksman New Member

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    You need to plunk test your chamber. Get a clean piece of fired brass (not resized) - pick one that the bullet has a bit of neck tension with but you can still push it down and pull it up. Set the bullet it so it barely sits in the case mouth, then take the barrel out of your slide and push the "cartridge" down until flush. Carefully remove the cartridge from the barrel and measure the OAL. That's the length to the rifling. Subtract .015 from that measurement and that's the max you should be loading to. I would suggest subtracting .020 and rounding down to to the nearest .005 and trying to set to account for some variance in bullet / case combo. Cast bullets are less uniform than are their jacketed/ plated brethren.

    Yes that's way shorter than book length and you're going to lighten up your charge significantly to compensate then work up.

    On my CZ's I have to load the Acme 124 RN coated down to 1.060. That profile feeds pretty harshly in my pistols to the point where it will fail to go into battery sometimes if I am cycling the action by hand. I switched to SNS Truncated Cone 125's (they're really 124s) - you can load these longer (generally) than most 124 profiles. If you *have* to have the book length you may be looking at the Bayou 124 RN profile with the lube groove - it loads the longest of any I have tried. As a data point - 3.8 grains of TG will push an ACME at about 1050 FPS at 1.060 OAL through my CZ shadows.
     

  3. forgetaboudit

    forgetaboudit New Member

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    I will give that a shot when I get home. I appreciate the help. Is there any sort of formula to figure out how much to reduce the charge for a deeper seated bullet?
     
  4. HumbleMarksman

    HumbleMarksman New Member

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    It's tough to say because the book value you're basing this off of doesn't have the exact same projectile shape as what you're loading. If you know the length of the projectile in the book you can back into it.

    The formula would be Projectile Length - (COAL - the length of a 9mm case resized [going from memory, I think it's .746"). The number that yields is how much of the base is in the bullet is seated in the case (seating depth) and comparatively the approximate space in the cartridge for combustion.

    Compare the book value seating depth to the to what you're having to load at - whatever % that is multiply it by the starting charge weight and work up a ladder with a chrono. The book should tell you that at XX velocity you're approximately XX pressure or whatever.

    Regardless what your length is, I'm guessing you will be laddering up from 3.4 or 3.6 to 4.0 grains of Titegroup. Probably settling in on the 3.8-4.0 depending on what velocity you need (assuming you want minimum power factor for the shooting sports? )
     
  5. forgetaboudit

    forgetaboudit New Member

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    So I did the plunk test with the ACME 124's and came up with 1.080 then minus .020 to 1.060. I pressed one to 1.060 and found that it doesn't spin in the barrel (hitting rifling?) I charged 5 rounds at 3 grains, and pressed them to 1.048 and they spun freely in the barrel. I then went out and shot them one at a time all the while inspecting the gun and the ejected shells. Nothing out of the ordinary.

    I wish I had a chronograph to test my rounds and go from there, but I don't unfortunately.:(
     
  6. HumbleMarksman

    HumbleMarksman New Member

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    I would expect that 3.5 grains or so would be a close to 127-130 PF load - about where you want it provided your gun cycles/feeds it. Next go around spring for some cone projectiles - they can load longer.

    That said, that is a VERY short throat.
     
  7. forgetaboudit

    forgetaboudit New Member

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    I've tried loading a few round with my Lee Pro Auto Disk powder measure with the adjustable charge bar installed. I can get consistent drops of 4gns but if I dial it back to get to my 3gn, it throws all over the scale. Most of the time it'll only drop .2gn.
    Can the issue be that the measure and Titegroup don't work properly together at such a low volume?
     
  8. HumbleMarksman

    HumbleMarksman New Member

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    The adjustable charge bar on the PAD is kind of a bear. The aperture on the bar doesn't line up with the opening in the hopper at low volumes - you can modify it, OR you could buy the lee auto drum. This is THE drop to have on a lee press. I know the answer you were looking for wasn't "go spend $40 on a new powder drop" but short of getting a Dillon press that's the best answer I have sadly. If I were loading with large flake powders like 700x, Clays, etc. I would would actually use that on my 650.
     
  9. forgetaboudit

    forgetaboudit New Member

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    I dug around in my box of reloading accessories and found a lee perfect powder measure. I was able to dial it in to drop 3 grains. But now my issue is that my bullet seating die isn't seating consistantly. Some will be at 1.038 and others 1.053. I have had nothing but issues after I switched to the Acme 124 LRN and Titegroup. I am going to see if a buddy of mine wants to buy the remaining bullets I have and maybe the powder too. I think I might switch back to Berrys 115 rn and maybe try the titegroup with them, but there again, the charge is so low I may not be able to drop using the auto disk/charge bar. The whole reason I switched to Titegroup from HS6 was to find a cleaner powder, and this is getting frustrating.
     
  10. HumbleMarksman

    HumbleMarksman New Member

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    How "mechanical" are you with your lee? I assume it's a turret. I had pretty consistent ammo on my turret before swapping over to a 650 - but I made every single stroke the same to the extent I could. How confident are you in your technique?

    I would recommend the new Alliant Sport Pistol. that's the next one I'm going to load, it's a poor man's Vhiti Vhouri N320. charge weight for a 124 should be 3.8-4.2-ish.

    If you're doing a lot of pistol shooting - again not a popular answer- but a Square Deal B or a 550B might be a good investment.
     
  11. forgetaboudit

    forgetaboudit New Member

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    I have a single stage at the moment. I've only been loading for a year now and only for my M9.
    I always try to be smooth and at a relatively slow speed, especially when throwing charges.

    I might just stick with 115g as my M9 didn't seem to like the larger 124g Only reason I got the 124 was to try something new.
     
  12. HumbleMarksman

    HumbleMarksman New Member

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    124's are perceived as a little less snappy than 115's - but in my experience ammo loaded with the same powder to the same power factor doesn't feel wildly different - the slide velocity changes for sure but the difference isn't huge. lighter faster projectiles are generally more accurate.
     
  13. forgetaboudit

    forgetaboudit New Member

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    The thing my pistol didnt like was the size of the tip. The seating depth was too deep, thus me not knowing exactly what size charge to put. Thats all goes back to my original post. The 115s are cheaper as well, so switching back to them will solve a few issues.