View Full Version : What causes this type of jam and was I correct in my diagnosis
I was at the range today and met a guy there that was shooting his new Bushmaster Carbon-15 (the model with the polymer upper and lower). It was a new gun, his second time shooting it, but after just a few shots it jammed on him. When I went to help him clear it I found a jam I've only seen once before.
The live round had managed to jam itself with the rear of the case on top of the bolt up against the gas tube. He tried pulling the charging handle to the rear but all it did was pull the entire live round on top of the bolt inside the upper with the rear of the case jammed against the gas key and the bullet itself jammed against the gas tube.
Obviously we couldn't just separate the upper from the lower because the BCG was stuck halfway in the buffer tube and halfway in the upper. I had to remove the buffer tube assembly, stock end plate, castle nut, etc. to take enough pressure off the BCG to separate the upper and the lower just to clear the live round.
After clearing it and reassembling the lower I noticed that the gas key and gas tube were damaged by the live round. The top of the gas key was bent inward and the gas tube was bent up and edges were bent in. Both were damaged in such a way that the charging handle made contact with the gas tube when reassembling and there was not enough space for the gas key in between the handle and tube so reassembly was impossible. So his jam turned into needing a new gas key and gas tube.
He was using a brass catcher and reloads and thought that had something to do with the jam but I disagreed. My thoughts were that since he was using a standard carbine buffer it was too light causing the BCG to move too fast thus causing bolt bounce; which caused the round to get jammed on top of it. I told him that once he got his gas key and tube replaced he needed to buy an H-buffer from Bravo Company to avoid this again in the future. Hopefully some of yall that know far more than me have seen this type of jam so you at least know what I am talking about.
So what causes this and whats the solution. Am I correct in my thinking?
It sounds like bolt over ride or charging handle impingement (I get the two mixed up).
Easiest way to fix it is to:
Remove magazine
Tilt the barrel forward while keeping it in a safe direction
Pull back the bolt as much as possible to the rear, then press down hard on the bolt catch to put pressure on teh bolt and keep it back.
Karate chop the charging handle forward and the case shoudl fall out.
This should help (http://www.youtube.com/watch?v=-TqLnBd1udM)
ETA: THe onlt times I have ever seen this type of malfunction is when brass has bounced back in the gun while shooting in unconventional positions
PJ
Cagemonkey
01-05-11, 19:25
Casing stuck between bolt carrier and charging handle. 1. Put rifle on safe. 2. Remove magazine. 3. Do not pull charging handle. 4. Insert cleaning rod section/screw driver or similar tool (I've even used my pinky finger) in ejection port and pull bolt back. Casing should drop through mag well.
Casing stuck between bolt carrier and charging handle. 1. Put rifle on safe. 2. Remove magazine. 3. Do not pull charging handle. 4. Insert cleaning rod section/screw driver or similar tool (I've even used my pinky finger) in ejection port and pull bolt back. Casing should drop through mag well.
Just curious why you say not to pull the charging handle?
PJ
Just curious why you say not to pull the charging handle?
PJ
The casing is stuck between the front of the charging handle and the BCG. If you pull on the charging handle, you can end up jamming the casing even more and getting it stuck to where you have to reach in there and pry it out.
Cagemonkey
01-05-11, 20:00
Just curious why you say not to pull the charging handle?
PJ
With the casing being jammed between the bolt carrier key and the charging handle, pulling the charging handle just jams the casing in tighter making it more difficult to clear the jam. The bolt needs to be retracted without using the charging handle. Having the charging handle locked fully forward stops the charging handle from moving when the bolt is retracted manually (not using charging handle).
I see your points, but I have never experienced the use of the charging handle making the problem worse.
Please check out the link I posted in my first post to clarify the technique I am referring to, to see it in action.
PJ
shittercrewchief
01-05-11, 20:14
This is called a "type ate malfunction" or bolt override. One of the less common malfunctions but one of the more trouble some to undo.
Best way to clear is to pull back on charging handle just enough to get some sort of tool on the bolt face to apply pressure on bolt. Then push for ward on CH this should get it lose.
I see your points, but I have never experienced the use of the charging handle making the problem worse.
Please check out the link I posted in my first post to clarify the technique I am referring to, to see it in action.
PJ
I've seen that video before. If you watch carefully, you will notice that the casing is stuck between the bolt face and the front of the charging handle. Moving the charging handle will not jam it more in this case.
Sometimes the casing ends up completely above the bolt. Using the charging handle in this case could wedge it in even more. FWIW, I've had it happen to me twice just shooting off the bench. Once on a range rental Colt and once on a Bushmaster. But, this type of malfunction is exceedingly rare.
I've seen that video before. If you watch carefully, you will notice that the casing is stuck between the bolt face and the front of the charging handle. Moving the charging handle will not jam it more in this case.
Sometimes the casing ends up completely above the bolt. Using the charging handle in this case could wedge it in even more. FWIW, I've had it happen to me twice just shooting off the bench. Once on a range rental Colt and once on a Bushmaster. But, this type of malfunction is exceedingly rare.
Both charging handle impingement (round is on the bolt face angled into the CH) and bolt override (round completely over the bolt) are adressed in that video and fixed with a similar course of action as demonstrated by that video.
Also Micheal Pannone in his writing describes the fix in the same way.
PJ
Both charging handle impingement (round is on the bolt face angled into the CH) and bolt override (round completely over the bolt) are adressed in that video and fixed with a similar course of action as demonstrated by that video.
Also Micheal Pannone in his writing describes the fix in the same way.
PJ
Agreed. There is no need to remove anything other than the magazine from the firearm in either type of malfunction. The use of knives, multi tools, hand tools, cleaning rods and the like are also not necessary.
It may take more than one hit, but judo chopping the charging handle after removing the magazine, and locking the bolt to the rear is the best way. I know this because I recently spent some time doing this over and over (along with other malfunctions) in a block of instruction that was part of a training course. The malfunctions were also deliberately induced.
I think I see what ya'll are trying to say. After the bolt is locked back, the friction of the charging handle rubbing against the stuck casing should loosen it up, right?
You are creating space for the round to fall out by putting the bolt as far to the rear as possible and the CH forward.
PJ
as far as WHY it happened.. bolt overrides on LIVE rounds are generally magazine problems- the magazine lets a round loose and it rattles in the action till the bolt sweeps over it and binds up.
I wish they were exceedingly rare; I guess once in 30 years and who knows how many Ks of rnds is rare but mine happened during a FF in Iraq.
When my gun went down and I couldn't immediately fix it I traded with the monkey next to me who proceeded to jam it completely...he pulled the CH as hard as he could, then speared the case with his multitool, tearing any gripable/accessible part of the case away.
It was ultimately cleared by removing the stock/extension, freeing the BCG enough to get it out.
Great thread, before tonight I had never heard of this malfunction. Thank you everyone for posting your thoughts and all of the information.
bkb:
Considering the "why", what signs should we look for in magazines in order to prevent this from happening? I am assuming that it is most likely a result of cracked, or spread feed lips?
ForTehNguyen
01-07-11, 07:36
Considering the "why", what signs should we look for in magazines in order to prevent this from happening? I am assuming that it is most likely a result of cracked, or spread feed lips?
yes, feed lips that are not holding the rounds in the magazine securely. My friend had an old 20 round metal mag that on the last round, if you slap the bottom of the mag, the cartridge just pops out on its own.
Great thread, before tonight I had never heard of this malfunction. Thank you everyone for posting your thoughts and all of the information.
bkb:
Considering the "why", what signs should we look for in magazines in order to prevent this from happening? I am assuming that it is most likely a result of cracked, or spread feed lips?
yep.. either warped lips, or cracks on the lips or at the spine of the mag, allowing the lips to spread.
but who actually inspects all their magazines? unfortunately, you generally discover bad mags by them malfing your gun...
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