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Thread: Load for an 300 black AR

  1. #1
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    Load for an 300 black AR

    Anyone using the NOE 311 155 GC in an 300 blackout AR platform?

    What you using for the load?

    I've tried 296, Lilgun, 5477, and 1680.
    If I get the action to cycle properly it leads up the gas system bad enough in < 60 rounds that the gun locks up.

    This one is frustrating the heck out of me.

  2. #2
    Boolit Master

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    What is the diameter of the boolits you have been casting? I've been shooting quite a few of the Lee 312-155 through my Blackout and I have yet to have any leading problems in my gas system. You are gas checking them, right? What are you using for lube?

    Might be worth finding something to catch a fired boolit and examine the engraving marks for gas cutting. A snow bank reportedly makes an excellent boolit trap.

  3. #3
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    Yeah they're checked.
    barrel slugs at .309. sized .310 - BAC lube.

    I've tried everything I could think of including hardness from 8 - 35.
    No lead in the barrel that I can see or get out, only in the gas system.

    I just started on a 311 247 NOE load, I'll try a bunch of them Monday and see if I get the same effect.

    I'm beginning to wonder if there isn't a burr at the gas port that is shaving lead off.

  4. #4
    Boolit Master

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    A burr could be the problem. Load up a few 110 to 125 grain jwords to high velocity and let er rip. That should take care of any burr. I have also used some lapping compound on a cleaning patch to smooth out a few barrels before, seemed to work good and it might help in this case. Try running a cloth patch through the bore with a .22 jag and see if it snags around the gas port area.

    Are you crimping the cases after loading? If so, might be shaving a little lead upon firing.

  5. #5
    Boolit Master

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    I have the Lee 312-155 and I size to .310 and use 15.5gr H110/W296. No leading and no lead in any of the gas system, have shot hundreds of them without cleaning, in 2 rifles.

  6. #6
    Boolit Master
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    I'd love to see pictures of this! Are you saying there is lead backed up into the bolt area where the gas comes into to work the BCG? Do you see lead in the tube at the reciever end? Now I had a problem with my 5.56mm AR if I used filler it would gum up the action(Chamber) to where it wouldn't feed and chamber(Lockup) after about 30 rounds! Stop putting filler in the rounds -no more problem! As for my 300 blk I just ran 40 rounds through it the other day -zero leading in the barrel- BCG no dirtier then when shooting jwods!

  7. #7
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    well, next time I get it to happen I'll shoot pix for ya.

    Things went well today - 12gr RL7 under a NOE 311 247 for ~ 1060 fps.
    Cycled well and didn't lead, although it was Very dirty, lots of unburnt powder.

    The lead builds up on the back the the bolt (blown through the key) and gets into the gas rings. It will eventually clog the rings and you get a lot of gas blow by.
    The first time it almost closed the exhaust holes in the carrier.
    It also builds up at the back of the gas tube/key.
    After a lot of rounds, ~55 - 60 (the last few in two 30 round mags jam)
    The last couple of mm of forward travel of the carrier jams the gas key onto the tube and it locks there.
    While it will continue to cycle for a while ( ~ 20 rounds) before it won't close enough to fire. < I only did this once, when I discovered the problem, as it's close to an out of battery situation.>
    It will fail to fire, and you won't be able to open the bolt because it's 'soldered' in place.
    I have to clean the lead out of the key to free things up.
    And of course you have to scrape the lead off the gas rings (and out of their groove) so that they are normal also.

  8. #8
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    Man, that sounds like a pain. I will watch to see what you find out.
    I came into this world kicking, screaming, and covered in someone elses blood. I plan to go out the same way.

  9. #9
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    I have the same problem. Here is pic of lead on bolt.

    I am shooting the same bullet (247 NOE). Gas checked and lubed with alox. Will be looking for a bur and will be changing lube.
    Click image for larger version. 

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    Last edited by Wedgie; 03-04-2013 at 06:53 PM.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check