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Thread: Help with a AR-15in 300 blk

  1. #1
    Boolit Buddy 43PU's Avatar
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    Help with a AR-15in 300 blk

    I just bought a completely upper from live free armory in Florida. It is a 16 inch barrel with pistol length gas and a 1/7 twist.

    The problem is when the bolt goes home the bolt sticks to the point to get it open I have to grab both sides of the charging handle and put the stock on my chest and pull as hard as I can I mean I'm 6'4 and it is hard for me to rack open. I have shot about 100 rounds of FMJ through it and it just doesn't like cast any ideas to help with the lock up?

  2. #2
    Boolit Master
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    Check the neck OD size of a fired case against a new boolit loaded neck.

  3. #3
    Boolit Master Boolit_Head's Avatar
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    Check your OAL as well it may be sticking in the throat.

    Also mortaring the action could help, pull back on the charging handle and bump the stock on the ground to free the bolt.
    On every question of construction let us carry ourselves back to the time when the Constitution was adopted, recollect the spirit manifested in the debates, and instead of trying what meaning may be squeezed out of the text or invented against it, conform to the probable one in which it was passed.

    Thomas Jefferson, letter to William Johnson, June 12, 1823

  4. #4
    Boolit Buddy 43PU's Avatar
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    No the bolt is sticking on an EMPTY rifle

  5. #5
    Boolit Master Boolit_Head's Avatar
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    Yikes that indicates something is really wrong. Was the bolt supplied with the upper? If so I'd be on the phone with the supplier you got it from.
    On every question of construction let us carry ourselves back to the time when the Constitution was adopted, recollect the spirit manifested in the debates, and instead of trying what meaning may be squeezed out of the text or invented against it, conform to the probable one in which it was passed.

    Thomas Jefferson, letter to William Johnson, June 12, 1823

  6. #6
    Boolit Buddy

    Tnfalconer's Avatar
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    That is interference with the bolt head and barrel adapter. Before you do anything else, strip the upper and check the barrel adapter for obstructions. Then remove the bolt head from the BCG and check it's fit to the barrel adapter. That will tell the tail.

    If those are all ok, check and or lube your bolt. It may not be rotating in the assembly to lock and unlock as it is retracted.

  7. #7
    Boolit Buddy

    BUCKEYE BANDIT's Avatar
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    "If those are all ok, check and or lube your bolt. It may not be rotating in the assembly to lock and unlock as it is retracted. "

    Had to run mine REALLY wet for the first few hundred cast loads.
    "The remedy for evil men is not the abrogation of the rights of law abiding citizens. The remedy for evil men is the gallows." Thomas Jefferson

  8. #8
    Boolit Master

    lefty o's Avatar
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    id send it back, you shouldnt have to fix something new.

  9. #9
    Boolit Buddy
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    Look at the bolt lugs with a magnifying optic, especially the lug surface that faces the rear. You're looking for a high spot that is polished, that's probably where it's hanging up. Also eyeball the rest of the lugs surface, never know what you'll see.

    You can also put Magic-Marker on the bolt and see where it gets wiped off, something like Dykem, machinist marking fluid would be best.

  10. #10
    Boolit Buddy 43PU's Avatar
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    Yeah I do run my rifles really dry i will try adding a big more lube

  11. #11
    Boolit Master
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    Quote Originally Posted by 43PU View Post
    Yeah I do run my rifles really dry i will try adding a big more lube
    ARs need to be wet. Motor oil works just fine.

    That said, bargain AR uppers tend to be roughly finished, so inspecting for burs with a bright light is a good idea.

  12. #12
    Boolit Master

    Moonie's Avatar
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    My sons new 223 Abe upper is hanging up on the barrel extension. I told him to manually cycle it with no ammo about 500+ times to smooth things out a little.ive seen that advice given for new tight ar's before.

  13. #13
    Boolit Buddy
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    Another for the wet run, most of the problems I've encountered with AR's were because of not enough lube.
    "People in Arizona carry guns," said Detective David Ramer, a Chandler police spokesman. You better be careful about who you are picking on...

  14. #14
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    curator's Avatar
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    Quote Originally Posted by 43PU View Post
    . I have shot about 100 rounds of FMJ through it and it just doesn't like cast any ideas to help with the lock up?
    If your problems are ONLY with cast boolits, you need to do a little research on various neck thicknesses of the parent cases used to make the .300blk brass. Your FMJ slugs will measure .308 but a proper cast boolit will be in the .310-.311 diameter. The slightly larger cast boolit can result in a cartridge neck being a bit too large to chamber/extract easily. I had this problem initially when first reloading cast in the .300blk. Using the correct brass eliminated it. While you are researching brass to make .300blk out of, research the "pogo-stick" method of clearing AR rifles.

  15. #15
    Boolit Master Boolit_Head's Avatar
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    I forgot about that. I chose Lake City brass to convert so the neck thicknesses are ok for cast. Various other head stamps have varying thickness brass at what ends up being the neck on a blackout. Some are way to thick to even chamber with jacketed.
    On every question of construction let us carry ourselves back to the time when the Constitution was adopted, recollect the spirit manifested in the debates, and instead of trying what meaning may be squeezed out of the text or invented against it, conform to the probable one in which it was passed.

    Thomas Jefferson, letter to William Johnson, June 12, 1823

  16. #16
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    If on an empty gun, you have a bolt to extension fit issue as said above it may be as simple as a high spot on the back of a lug
    check carefully with a magnifying glass . if found lightly polish and gun gun very wet for 100 rds or so and it will wear in
    if no hi spot found and your not gun smith handy return for replacement
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  17. #17
    Boolit Master 308Jeff's Avatar
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    If it were me, I'd send it back.

  18. #18
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    Texas by God's Avatar
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    Squirt a fair amount of 3in1 in those two holes in the valley of the bolt carrier and shoot a bunch of cheap ammo. I've seen TiN wonder bolt carriers balk when dry.

  19. #19
    Boolit Buddy
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    Quote Originally Posted by 308Jeff View Post
    If it were me, I'd send it back.
    But you don't learn how and why when you send it back; what does he do in a couple of years, has the same kind of problem? Or with a used gun, without a warranty?

    If you're a complete zero with anything mechanical, then send it back; you'd probably cause more damage messing around with it.

  20. #20
    Boolit Buddy 43PU's Avatar
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    I bought the brass here made from.LC13 and it does very good I have checked the throat of the rifle and checked the empty brass I always make sure to size my bookies to .310 which is .005 bigger than an empty neck on a fired case. I'm not completely stupid with guns I have built 13 AKs and a couple of rifle, I even shoot in the Allegany(spelling?) sniper match once a year. I just don't know squat about ARs but I wanted a 300blk and thought I would get the upper. I have a 7.62x38 ultra which is a 7.62x39 straight walled with a AI shoulder on it where I can get 308 velocity. 2 5.56 uppers, a 458 socom upper and a 204 Ruger upper. All of which total have had less than 100 rounds put through them...I'm just not an AR guy which is why I came here with my problems. Thanks for the help

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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