KB'd my 9mm AR today...

AR/M4 AR General Discussion
1

Well I spent the day at the range today with my new BCM 11.5" upper and tried to put some rounds through my 9mm AR.

I put about 100 rounds through the 9mm with no problems. It sounded great with the Matrix9 on it.

Down at the 50 yard range I proceeded to put another mag through it. Then all of a sudden BOOM. One of the rounds blew shit all over my face and arm from out of the ejection port.

I turned the rifle over and saw an obliterated case halfway out of the ejection port:


http://www.zoto.com/suicidehz/img/original/7c7b9ef2c72df853735f68e25344e50e.jpg

I dislodged it and was like “holy $hit!” I almost went to put the mag back in after I cleared it but thought to check the chamber. Sure enough, there was a 147gr. Rainier with it’s a$$ sticking out of the chamber.

So I knew that was it for the day as far as the 9mm went as I hadn’t brought any steel cleaning rods to try and bang it out with.

So I get home and go to pound it out. Rod goes about 9" into the 10.5" barrel. I ghasp very loudly. I bang on it with a hammer and it drops the rest of the way. I then proceed to bang VERY hard with the hammer until I pop out not only one, but two bullets.

I must have had a squib round- it went about 3" into the barrel. This poor case didn’t stand a chance when the second bullet decided it wasn’t going to move past the chamber.

I’m so thankful I didn’t blow myself up. I got down on my knees in the garage and gave the guy upstairs a big thanks.

Click on links below pictures for larger images.


http://www.zoto.com/suicidehz/img/original/e2f983e7dfe5c707fc55d7a210d288b2.jpg1


http://www.zoto.com/suicidehz/img/original/5a1265feb5b35c42b3c27e46cd906e7c.jpg


http://www.zoto.com/suicidehz/img/original/2ebc4f894761f06338bac19a7b39310d.jpg


http://www.zoto.com/suicidehz/img/original/385835ddf067c03b8db4e0b2d68c667d.jpg
Click the above link. This one shows some really nasty deformation in the brass!


http://www.zoto.com/suicidehz/img/original/605fa2a52d79bddb731589fd2be43a2f.jpg


http://www.zoto.com/suicidehz/img/original/e401ef2923c5939b5a78556de8438680.jpg


http://www.zoto.com/suicidehz/img/original/1cd61fe2290d9b7b85228ac391011c83.jpg


http://www.zoto.com/suicidehz/img/original/feaa3195c66045f1d0e777fc9b9ff3c4.jpg


http://www.zoto.com/suicidehz/img/original/3b281c34e55ab8f13ee3f455cec13804.jpg

Squibbed bullet on right, KB bullet on left:

I had one popped primer in the BCM that was a BITCH to clear too. It had gotten itself on top of the bolt, in the cam pin channel behind the pin.

Had to pull the pins and slide her off forward to get her apart.

What a day…

2

Wow! Good day to give thanks for sure… Glad you are OK! How is the rifle?

3

So the rifle is fine then?

4

With a bullet already lodged in the barrel, this could have turned out A LOT worse than it did.

Good to hear that the damage to you was minimal.

What damage was done to the gun?

-Jeff

5

I don’t think any damage at all was done to the gun.

I took off the handguards and measured the OD of the barrel in front of the chamber. 0.669" everywhere I measured it.

Inside of chamber is clean now and looks fine. No outside visible evidence of damage- no deformation, discoloration, anything of that sorts.

I should chuck it in the vice and remove the barrel and take some pictures as well as measure the chamber and areas in front with the calipers as I rotate it to make sure nothing is out of round.

I guess this is one reason to go with Colt? HP tests? MPI etc.?

The barrel is marked 2/99. Isn’t that awful old. Has it’s bayo lug though.

Thanks for the good words guys. I walked away with nothing more than sunburn and dirty sunglasses.

6

You may want to wear more than sunglasses when you shoot.

I see rookies do that a lot, shoot with sunglasses or none at all.

How long have you been shooting?

7

xxxxx

8

Silver primer in a Winchester case. It was a reload.

9

I usually always wear safety glasses. It’s been all indoor shooting for me for so long, I mistplaced my tinted glasses and all I had was clear. It was too sunny for clear but then again I had one too many KBs for plain sunglasses too…

Yes, they were reloads. 3.6 grains of Accurate #5 and CCI Small Pistol Primers.

10

Glad you’re OK. I’m sure you fun meter pegged on that one.

Were they crimped?

11

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.

12

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? :smiley:

13

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.

14

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.

15

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.

16

Glad your not dead or missing something!

C4

17

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

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!

18

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.

19

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.

20

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.