Page 2 of 4 FirstFirst 1234 LastLast
Results 11 to 20 of 37

Thread: KB'd my 9mm AR today...

  1. #11
    Join Date
    Jul 2006
    Location
    Northwest IN
    Posts
    3,119
    Feedback Score
    2 (100%)
    Yes, Crimped.

    Would it have been worse had it happened earlier at the 25yd when I was bump firing from the shoulder?

    Now that I've gotten it to run reliably suppressed after ramping the bolt and such, it is very easy to bump from the shoulder- controlled to a certain extent.

  2. #12
    Join Date
    Jul 2006
    Location
    Northwest IN
    Posts
    3,119
    Feedback Score
    2 (100%)
    Outside of chamber measures 0.999" +/- 0.001 all the way around front to back.

    Area in front of silver ring measures 0.800" +/-0.001 all the way around, front to back.

    It was a tight fit going in and coming out of the A1 upper but it spun smoothly and went back in without a hitch.

    Should I engrave a little 4 leaf clover on the side of this upper, same spot Noveske's cross goes?

  3. #13
    Join Date
    Jun 2006
    Location
    Colorado Springs
    Posts
    1,857
    Feedback Score
    0
    Quote Originally Posted by SuicideHz View Post
    Yes, Crimped.

    Would it have been worse had it happened earlier at the 25yd when I was bump firing from the shoulder?

    Now that I've gotten it to run reliably suppressed after ramping the bolt and such, it is very easy to bump from the shoulder- controlled to a certain extent.
    That's weird. Only thing I can think of was no powder dispensed in the squib case or a contaminated primer that didn't ignite the charge properly. AA#5 ought to dispense easily, it's not like it's a bulky, flake powder that doesn't meter well.

  4. #14
    Join Date
    Jul 2006
    Location
    Northwest IN
    Posts
    3,119
    Feedback Score
    2 (100%)
    I've used up a pound of AA#5 on 9mm and 45 so far. I used to use like .43cc on the rounds for the 92fs to get it to cycle but it was loud in the Colt. I JB welded a 1.06cc disk shut and redrilled the hole. It was way too small so I took a small unibit step drill bit and hand reamed the hole little by little to get up to 3.6.

    The nice thing is, even with the small hole, the top is wider than the bottom so the powder fills that small hole better and funnels through more easily.

    I always try to remember to shake the powder feeder well after I turn it back "on" (lee) so I always get a full load.

    I don't know what happened. I'm just lucky it didn't blind me.

    I shouldn't be surprised it didn't ruin the receiver- after all- look at the casing. It looks like the brass literally liquified and then quickly cooled forming that weird texture.

    I am very thankful the barrel didn't bulge at all. Thankfully this is blowback and any resistance is quickly overcome and all the energy is blown out of the ejection port- the bullet never even tried to make it into the barrel.

  5. #15
    Join Date
    Jun 2006
    Location
    Colorado Springs
    Posts
    1,857
    Feedback Score
    0
    I use a Lee measure and I always visually confirm the charge bar slides all the way over the drop chute. If you short stroke the handle, the bar won't slide far enough over and you'll get a short fill. If you don't have the swivel adaptor, get one. It allows you to position the measure so you can watch the whole process very easily.

    I'm also wondering about your funnel-shaped charge cavity. Ball powder typically doesn't bridge, but if it's a significant enough taper, that's maybe what's going on. Do you have all the disks? I would think with the supplied disks you ought to be able to get very close to 3.6 grains without too much difficulty.

  6. #16
    Join Date
    May 2006
    Location
    VA/OH
    Posts
    29,630
    Feedback Score
    33 (100%)
    Glad your not dead or missing something!



    C4
    Last edited by C4IGrant; 06-10-07 at 16:17.

  7. #17
    Join Date
    Aug 2006
    Location
    east TN
    Posts
    110
    Feedback Score
    3 (100%)
    Quote Originally Posted by C4IGrant View Post
    Glad your not dead or missing something!

    C4
    so was i! it would have shortened our range trip a bit

    i was sitting right next to him at the bench rest when it went. i heard a word of surprise, and asked if it'd jammed (some low power rounds earlier at the 25yd range weren't fully cycling)... obviously this was a different situation. once i saw the case, i was very thankful there were no injuries!

  8. #18
    Join Date
    Jun 2006
    Location
    Colorado Springs
    Posts
    1,857
    Feedback Score
    0
    Quote Originally Posted by SuicideHz View Post
    I've used up a pound of AA#5 on 9mm and 45 so far. I used to use like .43cc on the rounds for the 92fs to get it to cycle but it was loud in the Colt. I JB welded a 1.06cc disk shut and redrilled the hole. It was way too small so I took a small unibit step drill bit and hand reamed the hole little by little to get up to 3.6.

    The nice thing is, even with the small hole, the top is wider than the bottom so the powder fills that small hole better and funnels through more easily.
    After rereading this, are you trying to load 3.6 grains of powder or are you trying to create a cavity that yields .36cc's of volume?

    If 3.6 grains, then change your strategy. AA's starting load is 4.8 grains of powder, so if you are loading 3.6 grains, that's way too light. Load the 4.8 and don't worry about the noise. Also, Lee's data lists their smallest cavity, the .30cc cavity, yielding somewhere around 4.8 grains. In my experience their data is pretty conservative so I wouldn't be surprised if it yields a bit less, but given you are using a tapered chamber with perhaps a charge weight less than what they list for the smallest cavity, i could see where you might be getting bridging and less than full charge weights.

  9. #19
    Join Date
    Jul 2006
    Location
    Northwest IN
    Posts
    3,119
    Feedback Score
    2 (100%)
    Thanks Grant (there I go "tugging your nuts again as xkaper would say)

    Yes, the smallest disk is .30cc. I am trying to load 3.6grains. I found that .30cc yields about 4.8. Much more than I wanted.

    I suppose I've had my fun and now loads should be at the 3.0cc.

    I've got another 200 rounds maybe of the light loads.

    Those are spooky quiet. We were hearing the 9mm rounds whizz down range and whacking the berm. It was outrageous. The only noise on our end was the loud clacking of the bolt.

    I had to resort to these low loads to get the suppressor quiet and the rounds to stay subsonic out of this barrel.

    The last 7 boxes of WWB 147 grain I got were very loud out of the 92fs at an indoor range. They may not have been true subsonics and I know they were cracking.

    I'm also thinking the suppressor is out of whack a little. I may contact Doug at SRT to check into it. It's throwing the rounds VERY high out of the A1. Maybe 2' high at 25yards with the front post up flush with the top of the base inside of the ears.

  10. #20
    Join Date
    Jul 2006
    Location
    VA
    Posts
    6,533
    Feedback Score
    8 (100%)
    Glad you're ok man.

    I've turned into one hell of a eye protection nazi because of similar stuff that's happened with me.
    Employee of colonialshooting.com

Page 2 of 4 FirstFirst 1234 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •