PDA

View Full Version : Broken Bolt



Chris_C
11-22-06, 15:10
I have no idea if this is one of my RRA's or another maker.

I was having FTE problems, found the issue today. It took me 20 minutes of play and speaking to to get the cam out, the firing pin didn't want to come out to easy either. I am unable to take the extractor pin out.

http://www.plantoneforme.com/ar15/brokenbolt.JPG

I had another AR with me, took out the BCG and kept on going. No problems after.

Is it possible that something "tracking" wrong in the upper and anything to do with it? Or just a bad bolt.

Bolt had no more than 8k to throw out. I got my use out of her.

I notice my cam is really gouged, more than I am used to seeing. If you notice, the crak is on both sides.

Glad I caught it when I did.

LukeMacGillie
11-22-06, 15:20
8k? thats about 3k more than what you should plan on with a carbine bolt.



I have no idea if this is one of my RRA's or another maker.

I was having FTE problems, found the issue today. It took me 20 minutes of play and speaking to to get the cam out, the firing pin didn't want to come out to easy either. I am unable to take the extractor pin out.

http://www.plantoneforme.com/ar15/brokenbolt.JPG

I had another AR with me, took out the BCG and kept on going. No problems after.

Is it possible that something "tracking" wrong in the upper and anything to do with it? Or just a bad bolt.

Bolt had no more than 8k to throw out. I got my use out of her.

I notice my cam is really gouged, more than I am used to seeing. If you notice, the crak is on both sides.

Glad I caught it when I did.

Pat_Rogers
11-22-06, 15:26
This is not uncommon. I have a picture book full of what you have experienced.

Guns wear, and gun parts wear. Military bolts will lose lugs somewhere around 4k-10k rounds. I have never seen- but have heard of- military bolts cracking around the cam pin hole.

I seldom see aftermarket bolts break at the lug- possibly because they are not subject to the harsh firing schedules of the military guns.
I have seen a lot of aftermarket bolts break at the bolt cam pin hole.
Most of these were bushamsters- probably because they have a larger share of the hobby market, but also dpms.
I have seen one bushamster bolt go at under 500 rds- much to the chagrin of the owner, who was the largst bm dealer in that state.
I saw 2 dpms bolts go- belonging to a husband and wife- on consecutive days.
The guns were low round count (one at appz 3k, the other under 1k. That is because the "match chamber" preventer her from completing an earlier class.

FYI- if it broke when firing it would not have been a mass casualty producer. The thing just stops running, with the forwaed part of the bolt locked up in the barrel extension, and the back end in the bolt carrier (i have a lot of pics of that too).

In the back of my mind i can't help but think that all of the aftermarket makers buy their small parts from the same manufacturer....

Chris_C
11-22-06, 15:30
If I remember right, I was on my 2nd set of rings...and I think a 2nd extractor spring as well. I could be wrong, I have moved the bolt around often.

5k, eh? Thats good stuff to know there. I was thinking I need to limit the life of these my self. And not wait for a serious failure.

LukeMacGillie
11-22-06, 15:43
This is not uncommon. I have a picture book full of what you have experienced.

Guns wear, and gun parts wear. Military bolts will lose lugs somewhere around 4k-10k rounds. I have never seen- but have heard of- military bolts cracking around the cam pin hole.

Pat,

PM me a good email for you, I have some PDF's from Crane with pics of .mil bolts that failed like the OP's did.

Luke


Edited since I realized that the info is releasable, check out

http://www.dtic.mil/ndia/2006smallarms/taylor.pdf#search=%22sopmod%22

Someplace about page 40 or so addresses broken bolts

Chris_C
11-22-06, 15:51
Pat,

PM me a good email for you, I have some PDF's from Crane with pics of .mil bolts that failed like the OP's did.

Luke


Edited since I realized that the info is releasable, check out

http://www.dtic.mil/ndia/2006smallarms/taylor.pdf#search=%22sopmod%22

Someplace about page 40 or so addresses broken bolts

Thanks for the info...

Pat_Rogers
11-22-06, 16:23
Thanks Luke- i have that. They were referring to Mk18's, correct, with very low round counts on the bolts.
We see more service life as the barrels get longer. Unkown if that means anything...

LukeMacGillie
11-22-06, 16:50
Thanks Luke- i have that. They were referring to Mk18's, correct, with very low round counts on the bolts.
We see more service life as the barrels get longer. Unkown if that means anything...

Pat,

AFAIK, that section is dealing with M4A1s

I need to get in contact with LGT about the roundcounters, since the number of bolts and uppers we are going thru has caught the ire of a beancounter.................

K.L. Davis
11-22-06, 17:13
the presentation (and WSC/DCD) is about M4s... for now.

Luke check your IM