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Thread: AR15 Bolt and Carrier Specs

  1. #1
    Boolit Buddy
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    AR15 Bolt and Carrier Specs

    Not making anything, only want to be able to inspect. Just spent an hour looking online for blueprints. Watched a School of the American Rifle YouTube where a bolt and carrier that wouldn't function was found to be out of spec just about everywhere. Parts were "pinned" using go, no-go gauges. Looked like a standard inch pin gauge set would work fine if you knew what the dimensional call-outs were (.xxx", +.xxx", -.xxx"). A link to or a copy of a blueprint anyone?

  2. #2
    Boolit Master

    rancher1913's Avatar
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    i wish he would sell copies of the tools he uses, he sure makes testing look ease
    if you are ever being chased by a taxidermist, don't play dead

  3. #3
    Boolit Grand Master



    M-Tecs's Avatar
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    2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

    "Before you argue with someone, ask yourself, is that person even mentally mature enough to grasp the concept of different perspectives? Because if not, there’s absolutely no point."
    – Amber Veal

    "The Highest form of ignorance is when your reject something you don't know anything about".
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  4. #4
    Boolit Grand Master popper's Avatar
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    IIRC the 'test' is to stand it up on the bolt head, if it falls immediately, too loose. Slight finger pressure and it drops, OK. Too much pressure, rings or back hole to tight. Something he said that kills gas system is too aggressive cleaning of the back 'tube', which is a gas exit. I think that is what you want to measure. Thinking out loud, maybe an air pressure test in the gas port to test, like a leak test? I know, 10k at the port to operate but in open air, should be much less.
    I know after shooting a lot of cast, the rings and the back tube get a lot of lead. Not sure the lead on the tube is bad thing. Kinda a seal? Maybe carbon buildup is good too?
    Whatever!

  5. #5
    Boolit Buddy
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    M-Tecs - thank you sir. I trolled Homegunsmith.com, guess you need to be a member. Like a lot of things fitment is relative more to how two parts fit together than an absolute dimension in isolation. The go, no-go thing is likely more for a armorer to take a pile of like parts and select the ones to put in the pile to be reused. In the field two or three parts rifles can then make one good one without worrying about (for example) headspace.

    Popper, I plan on almost exclusively shooting lead. Even though I am not prone to dump a mag or otherwise burn up a bunch of ammo it's good to know I need to pay attention accumulation to the gas ring area.

  6. #6
    Boolit Buddy
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    Quote Originally Posted by scottnc View Post
    M-Tecs - thank you sir. I trolled Homegunsmith.com, guess you need to be a member. Like a lot of things fitment is relative more to how two parts fit together than an absolute dimension in isolation. The go, no-go thing is likely more for a armorer to take a pile of like parts and select the ones to put in the pile to be reused. In the field two or three parts rifles can then make one good one without worrying about (for example) headspace.

    Popper, I plan on almost exclusively shooting lead. Even though I am not prone to dump a mag or otherwise burn up a bunch of ammo it's good to know I need to pay attention accumulation to the gas ring area.
    I too run cast in an AR and this is valuable info. Thank you very much!

  7. #7
    Boolit Master Handloader109's Avatar
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    Well, I know that the bcg was out of spec on my new ruger 5.56. Sent back and they had to replace it for it to function. So it does happen.

    Sent from my SM-S908U using Tapatalk

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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