Crimping 300ACC reloads

Discussion in 'Handloading and Reloading' started by Jackiesman, Nov 18, 2021.

  1. Jackiesman

    Jackiesman Member

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    Wondering if anyone has experience in crimping 300ACC reloads. I always load near the minimum powder range, and recently loaded some 150 grain PSP rounds, and after firing kept increasing my loads up to mid range. When I fired the 1st of the midrange rounds I checked the next 5 LOA for movement, and continued the process until all 6 were fired. I found some evidence of bullet creep (.001 to .005/6), and it has me wondering if I should put a mild crimp on the rounds. I should add that the velocity over the crony was consistent, and like the lighter loads no abnormal slgns of pressure, I used LC brass at 1.365 with CCI SRP's at 2.200. Any insight would be appreciated.
     
  2. Walkalong

    Walkalong Moderator Staff Member

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    Lightly roll crimp into a bullet with a proper cannelure.
    That said, .005 of bullet creep isn't likely to hurt anything.
    300 Blackout with Hornady 123 Gr .310 Z Max - Modified Roll Crimp Pic 1.JPG
    300 Blackout with Hornady 125 Gr SST - Modified Roll Crimp Pic 1.JPG
    300 Blackout with Speer 130 Gr - Modified Roll Crimp Pic 1.JPG
    300 Blackout with 147 Gr FMJ - Modified Roll Crimp Pic 1.JPG
     
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  3. Jackiesman

    Jackiesman Member

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    Two things: I crimp my 06 and 338 with a light roll crimp. And I use a heavy crimp for my 375 H&H that I use in Africa. But with those I'm only dumping 1 or 2 rounds down range. Second thing is that I only fired 6 rounds through the 300AAC and had that much creep, and I agree with you that doesn't seem too be excessive. But comes the time when I 'm dumping a 30 round mag what are the ones at the bottom doing. That said, I have and use a cannelure cutter when I'm intentionally loading long or short, but with the wide range of bullet weights available for the 300 the factory cannelure sometimes is nonexistent or falls outside the LOA that I'm loading. I hope that better explains my concern for the very minor bullet creep I'm seeing. The pacesetter dies came with a factory crimp die which I could use if I need to put a little crimp to the rounds.
     
  4. reddog81

    reddog81 Member

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    Rattling around in a 30 round mag isn’t going to change to OAL unless something severe happens. The Setback occurs during chambering.

    I use a lee factory crimp die setup to just barely crimp the round to make sure the cartridge is loaded within spec.
     
  5. Walkalong

    Walkalong Moderator Staff Member

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    The collet style rifle FCD would certainly stop creep, may not be good for accuracy, just have to try. Have you run 28 through and checked number 29 & 30?
     
  6. jmorris

    jmorris Member

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    Measuring Length OverAll might not be the best way to see if the bullet is moving in the case.

    First, tip to base, is not always consistent from one bullet to another. Like these SMK’s, for example.

    4C147838-237B-46EE-890E-903E9C2EBDE1.jpeg 6BC3AC37-6D21-4B56-92CB-F5CF36E257E3.jpeg

    So measuring Length OverAll with these to will show a .005” difference, despite the two being seated to the exact same depth.

    You could also very easily distort the tip on soft point bullets so a way to measure from some point on the ogive would likely be more enlightening.

    They sell tools that amount to a hole that becomes your “datum” or reference diameter. This one has 6 different diameters to choose from.

    F61FEA3C-9DAA-4513-BB2E-0CF02D59848C.jpeg

    You can also get them where they attach to the blade on a caliper. A bit easier to use if your all thumbs.

    C1ED6A1A-2792-48BB-A706-C4D54E9BC8CA.jpeg

    Or you could just remove the seating stem from your die and use it.

    E04154C4-0482-4E6D-BAD9-A7BDF8055300.jpeg

    Those methods would at least let you know if they are moving vs having different lengths to start with or are being distorted only at the tip.

    FWIW, I don’t crimp my 300 blk at all.
     
  7. Lennyjoe

    Lennyjoe Member

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    Probably not much help here but I don’t crimp my .300 BO loads as I only load subsonic rounds for my SBR. The 190 Sub X doesn’t have a cannelure anyway
     
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  8. Jackiesman

    Jackiesman Member

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    Guess I'm leaving holes in my question. I'm aware that each bullet (especially PSP's and SP's) may vary considerably in length, which is why (when I'm test rounds) I measure, number and record the case length and OAL for each round. If if the bullet moves during clambering it would have a longer OAL, but I wouldn't know it unless I removed it from the chamber. But I'm measuring each round in the mag after each shot, and the OAL is getting shorter. But thank you walkalong, jmorris, and Lenny joe for your input. So far no one has mentioned crimping the 300. And I have a feeling that you folks have probably dumped a full mag or two with no problems. I will try a full mag and check for creep on #30 while watching the crony (it's a good excuse to shoot more). And special thanks for the tips on the ogive measuring tools. That will save some testing time.
     
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  9. jmorris

    jmorris Member

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    I understand what you are saying and think it is me that isn’t relaying the information properly.

    If you take a bullet out of the package, it should be in pretty good shape. Like the one on the right below. Have the tip contact anything during chambering, recoil and ejection for the subsequent measurement and it can be damaged, like the one on the left. Even if the bullet did not move in the case the OAL measurement will be different but ogive to base will be the same.

    A9396CE9-FECC-4C3B-83D8-BB2FB229FBFE.jpeg

    This is why I was suggesting ogive to base measurements, it removes tip distortion as a factor in your measurement.
     
  10. berettaprofessor

    berettaprofessor Member

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    I crimp my 300BLK. But then, I have LCD's for most all calibers and lightly crimp everything. I don't want to even think about setback and I'd like the crimp to be consistent.
     
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  11. Jackiesman

    Jackiesman Member

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    In some 35+ years of loading about 20 different calibers I have never experienced as many challenges as I have loading the 300 AAC.

    The latest occurrence was today when I loaded some 130 grain Speer PHP varmit bullets. I loaded to 2.135 OAL (well below the max), With a slight crimp. I always chamber a few rounds to verify fit. This time the first round would not manually eject. After finally getting it our of battery it showed that the bullet had contacted the lands. Resized it to 2.1 and got the same results, with two sets of rifling marks on the bullet. Finally got the rounds to properly function at 2.085 LOA And they went into battery just fine, and shot well.

    That said I'm wondering if anyone else has experienced this condition with that particular bullet? Or maybe others?
     
  12. Jackiesman

    Jackiesman Member

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    One more comment: contacting the lands was probably the root cause on the "bullet creep" I described in my opening post to this thread, especially using thr rounds without a crimp. I thing I will slug the barrel and see what I have for a chamber size.
     
  13. Walkalong

    Walkalong Moderator Staff Member

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    If it is the same bullet (Speer 130 Gr Varmint # 2005), I loaded them to 2.035 OAL with very god luck. Fed well shot well, good price, what's not to like.
     
  14. Jackiesman

    Jackiesman Member

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    It's the same bullet and once I reduced the LOA to 2.085 it feeds and shoots very well with good accuracy.
     
  15. Jackiesman

    Jackiesman Member

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    The saga continues: I tried to load some 110 grain round nose soft point for plinking, just fun shooting. Can't get them to feed from the mag, the point gets caught on the mag lip. Anyone have a hint? I considered trying to modify one of my mags, but before I try that I thought I would query to group.
     
  16. EricBu

    EricBu Member

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    This is really dependent on what you're using for brass? If you've converted your own, and it's not been annealed, the spring back is going to cause you to have reduced neck tension. 300 AAC shouldn't need a crimp, if you've got bullet movement, first place to look is neck tension, which is a pretty common problem as a lot of people don't anneal converted brass.
     
  17. Jackiesman

    Jackiesman Member

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    EricBu: thanks, good tip.
     
  18. kcofohio
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    kcofohio Contributing Member

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    Some magazines, especially polymer, don't have the front relieved enough for reliable feeding of rounds in 300 BO. So far, I have found D&H mags to be good for 300 BO.
    20211205_140646.jpg
    D&H on the left, and Del-Ton on the right.
     
  19. Jackiesman

    Jackiesman Member

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    Excellent piece of information. Thank you.
     
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  20. Gone Hiking

    Gone Hiking Member

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    I load heavy, powder coated lead bullets (subsonic) for 300 Blk. I had a learning curve, where I was having feeding issues. Virtually of it was solved when I switched from standard aluminum and pmags to 300 Blk-Specific Lancers.
     
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