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Thread: No HeadSpace Gauges, Whats The Likelyhood I'll Blow MY Face Off?

  1. #1

    No HeadSpace Gauges, Whats The Likelyhood I'll Blow MY Face Off?

    Just recieved an Aero Precision complete upper, from the factory. Also have a brand new AA bolt to go along with it and was planning on using that in a BCM bolt carrier.

    So, ............short of waiting on headspace gauges, are there any other things I could check/do, to increase my odds of not having any problems.

    Or, have I've completely lost my mind if i think Im going to shoot this thing before checking the headspace?
    Last edited by Harpoon1; 01-13-2018 at 12:33 AM.

  2. #2
    Warrior grayfox's Avatar
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    As long as they are both spec'd to the same dimensional bolt face depth, and as long as you have mocked them up with an empty unfired brass casing....
    I do an upper/complete bcg/bolt/charger/empty casing check (ie, no lowers, no loaded ammo) on the ones I plan to use together to ensure proper fit. Guide the casing in with your fingers after seating it against the ejector and engaged with the extractor.

    I haven't been in the mode of verifying every head space setting on barrels I received from reputable vendors...
    I do verify that both are for 0.136 bolt face depths (I don't care for the 0.125 version although they may work just fine, I have no experience with them).
    The barrel/extension and the bolt face both need to be for either 0.136" bolt face depth or 0.125". IIRC Aero should be 0.136 and should say something in its specs like "Grendel 0.136" or "Grendel II" head spacing.
    You can measure your bolt face depth with a caliper.
    Chuck Norris doesn't do push-ups, the earth does push-aways.

  3. #3
    Warrior grayfox's Avatar
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    O yeah one more thing... sometimes guys have found that even one type of factory ammo (pick your flavor) may not totally seat into their new chambers... so after all of that, it may be wise to verify that your ammo will seat properly... I have not encountered that problem but there are a few posts on the forum that talk about it.
    Chuck Norris doesn't do push-ups, the earth does push-aways.

  4. #4
    Yep, Aero Precision uses Ballistic Advatage barrels and they advertise "type II " chambers. The AA bolt is supposed to be 0.136 but I'll verify that and make doubly sure.

    The rest sounds good, thanks.
    Last edited by Harpoon1; 01-13-2018 at 12:40 AM.

  5. #5
    Warrior
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    I would put it together and fire the first round, single loaded, from the hip (with eye protection, hearing protection, etc). Confirm that it locks back on the empty mag.

    Do you happen to have the Hornady Headspace guage comparators? If so, compare your fired case dimensions to SAAMI specs.

    After building 3 or 4 Grendel uppers, I finally bought the Manson headspace gages. Measuring the gages indicated that if the fired case measures within the SAAMI specs, then you are good to go. I can go back to my my notes and provide more details if needed.

  6. #6
    Drillboss,

    Sounds like a good plan.

    Unfortunately, I've got nothing other than a micrometer at this point. I'll run a few rounds through it and see how everything looks. Im sure I'll have plenty of help and advice tomorrow at the range.

    Thanks for your help.

  7. #7
    Warrior
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    Headspace too tight: Round won't chamber.
    Headspace too loose: Potential for a parted case.

    If your barrel's chamber was machined for the proper bolt face depth, then manufacturing tolerances should put the headspace within where it needs to be. This is just my opinion based on what I've seen with my barrels. If anyone has other experiences, please chime in.

  8. #8
    Chieftain
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    Take a look at this thread, has information on where to rent gauges and other solutions.

    This thread didnít specifically apply to the 6.5 Grendel but still is relevant to this thread.


    http://www.65grendel.com/forum/showt...adspace-Gauges

  9. #9
    Quote Originally Posted by VASCAR2 View Post
    Take a look at this thread, has information on where to rent gauges and other solutions.

    This thread didn’t specifically apply to the 6.5 Grendel but still is relevant to this thread.


    http://www.65grendel.com/forum/showt...adspace-Gauges

    Thanks VASCAR2

  10. #10
    Chieftain Klem's Avatar
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    If you always fire the first round of a new barrel from the hip, and look away as you pull the trigger the likelihood your face will be injured is...zero.

  11. #11
    Warrior Sticks's Avatar
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    Quote Originally Posted by Klem View Post
    If you always fire the first round of a new barrel from the hip, and look away as you pull the trigger the likelihood your face will be injured is...zero.
    Your lower regions however...

    Quote Originally Posted by VASCAR2 View Post
    Take a look at this thread, has information on where to rent gauges and other solutions.

    This thread didnít specifically apply to the 6.5 Grendel but still is relevant to this thread.


    http://www.65grendel.com/forum/showt...adspace-Gauges
    Headspace gauges and reamer rent for Grendel

    https://www.reamerrentals.com/Produc...de=6%2E5GB%2Eg
    Sticks

  12. #12
    Quote Originally Posted by Drillboss View Post
    Headspace too tight: Round won't chamber.
    Headspace too loose: Potential for a parted case.

    If your barrel's chamber was machined for the proper bolt face depth, then manufacturing tolerances should put the headspace within where it needs to be. This is just my opinion based on what I've seen with my barrels. If anyone has other experiences, please chime in.
    From my experience, this is 100% correct. Headspace is set to standards that will allow for re-use of brass/re-loaded ammo. If you look at what the military uses you'll find that a bolt is allowed to have more head space than what we call max because the military never uses re-loads and the risk of a parted case is far less likely. Will a parted case blow up in your face.. Not likely, the bolt will still be in locked in place. Will it be a pain in the arse to remove the parted case.. Yeah, but they make tools that make it pretty easy.

  13. #13
    Klem & Sticks

    Pulled a bullet and tried some new Hornady brass. Definitely on the "snug" side going in. Needed a little prodding, some forward assit, to send it all the way home. Thats good, I think? Better than too loose "ey" ? And, the bolt lugs are tight, not much clearance coming out of lock up. Not sure what to make of that though. Difinitely much tighter than any other AR I've put together.

    Anyway, Im going to be cautious firing the first round or two, probably shoot it from around the corner, and from behind a barricade of some sort!

    Thanks

  14. #14
    Chieftain Klem's Avatar
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    Quote Originally Posted by Sticks View Post
    Well...what can I say? If you're worried about any part of your body getting injured you could knock-up a 'drip rifle'. The delay firing mechanism saved quite a few lives during the Gallipoli withdrawal in WW1.


    On a more serious note you could dig a section of 100mm PVC pipe into a earth mound like a safety-clear tube. Seems like a lot of effort for the risk though.

  15. #15
    Warrior
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    Firing my Grendel WITHOUT a gas block, gas tube, buffer or buffer spring.
    It worked fine.
    It had to be slammed closed since there was no spring assist but the manual extraction was easier since there was no spring desist.
    IMG_20170802_132336 (Medium).jpg

  16. #16
    So......made it out of there alive! No problems with the lockup, but several issues with the mags feeding and generally being under gassed.

    Ran 60 or 80 rounds of Wolf through it and one box each of Hornady 123 SST and ELD-M. Hated the Wolf, 4-5 MOA..bummer! Both the SST and ELD was around 1-1.5 MOA at 100. Not great but given the circumstances I can work with that. But the under gassing turned into a royal PITA. I grabbed the wrong lower, off a slammy carbine i hardly shoot anymore, and it was way over sprung for the midlength gas sytem and the Grendel. It had a red Sprinco spring and H3 buffer in it. Nada! Wouldn't lock open on the last round, wouldn't pick up another round. It went back just enough to reset the trigger and that was it. Finally figured that out and put another lower on there with a stock spring and buffer and it helped a little but there's still alot of room for improvement. The gas rings on the bolt were really snug in the carrier, so, I suppose things will improve somewhat as they wear in. I'm tempted to open up the gas port but may try a really light buffer spring and buffer first and see what happens.

    FWIW: some data points

    16" Ballistic Advantage barrel, in an Aero Precision upper, looks like maybe the Hanson profile barrel.

    Sea level, 40 F, clocked by Labradar

    Wolf 100 grn avg around 2460 fps, ES 81/23 SD
    SST 123 grn avg around 2325 fps, ES 58/ 14 SD
    ELD_M Black 123 grn avg 2345 fps, ES 39/11 SD
    Last edited by Harpoon1; 01-16-2018 at 09:40 PM.

  17. #17
    Bloodstained
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    Quote Originally Posted by Harpoon1 View Post
    Pulled a bullet and tried some new Hornady brass. Definitely on the "snug" side going in. Needed a little prodding, some forward assit, to send it all the way home.
    Take the upper off the lower, remove the BCG. A loaded round or sized piece of brass should drop into the chamber with an audible thud with the barrel pointed straight down. If you point the barrel straight up the round or brass should drop out freely. I also take the ejector and extractor out of the bolt and place it in the chamber with a loaded round or sized brass. It should rotate freely when it gets past the bolt lugs but it should not be sloppy.

    Your prodding and pushing using the forward assist was probably just getting the bolt seated over the rim of the case (resistance caused by the ejector and extractor).

  18. #18
    Warrior
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    Break in needed with new parts.
    Lube it and shoot it and it will work better after a while.
    Accuracy is about what I and others here have experienced with rack grade barrels.
    Accuracy will be better with handloads.

  19. #19
    Bloodstained kcb38's Avatar
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    Quote Originally Posted by Harpoon1 View Post
    So......made it out of there alive! No problems with the lockup, but several issues with the mags feeding and generally being under gassed.
    Being under gassed seems to be a fairly common concern with BA barrels. They admittedly use smaller gas ports than other manufacturers. I'm hoping I don't have that issue with my new 20" rifle gas barrel. I couldn't measure the port precisely but it seems to be in the 0.08X range which might be a little on the small side. I guess time will tell. Oddly enough the only other BA barrel I have might be slightly over gassed, given the fact that the rifle ejects at about 2 o'clock.
    - Kirk -

  20. #20
    Quote Originally Posted by koden View Post
    Take the upper off the lower, remove the BCG. A loaded round or sized piece of brass should drop into the chamber with an audible thud with the barrel pointed straight down. If you point the barrel straight up the round or brass should drop out freely. I also take the ejector and extractor out of the bolt and place it in the chamber with a loaded round or sized brass. It should rotate freely when it gets past the bolt lugs but it should not be sloppy.

    Your prodding and pushing using the forward assist was probably just getting the bolt seated over the rim of the case (resistance caused by the ejector and extractor).
    Koden

    Good to know, I'll try that in the future.

    I snapped the empty brass under the extractor and then held it down against the ejector while feeding it into the chamber. It felt like the forward assit was to get the lugs to clear the barrel extension so it could go into lock up.

    Thanks for the help.

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