Hammer catching on firing pin

[jrumann59]

I do have a notched hammer, and I agree that is causing the physical jam problem. But whether it's notched or not shouldn't matter. The whole issue is starting bc as the carrier is sliding backwards after pulling the trigger, as it cocks the hammer, the hammer isn't staying cocked, which in result makes the hammer try to rise and slide across the bottom of the bolt carrier as it slides to close, which then makes the notch in the hammer catch on the collar of the firing pin.

IMO it all starts with the hammer not saying cocked which means the disconnect isn't working? Getting a hammer that's rounded would only result in the gun cycling, chamfering a new round, but the trigger wouldn't be reset (since its not cocking it). The weird part is it cocks when you manually cycle the gun unloaded.

Got it, New FCG from joe bob fixes it for $80-ish maybe 100-ish if you want new hammer and trigger pins.

 

[NateIU10]

Disconnector spring in upside down? If this guy assembled it, I'd check that first in a heartbeat. I'd also swap out the notched hammer and unshrouded BCG (a trigger and NiBo BCG+hammer from the group buy would do quite well IMO.)

 

[Tylenator]

Try this function check with it unloaded
Try cycling it with the charging handle while you are pulling the trigger. Release the bolt, but keep holding the trigger. Then release and pull the trigger. Does it drop the hammer?/QUOTE]

yes the hammer drops. It fictions fine unloaded. But not when loaded.

 

[Threeband]

Try this function check with it unloaded
Try cycling it with the charging handle while you are pulling the trigger. Release the bolt, but keep holding the trigger. Then release and pull the trigger. Does it drop the hammer?/QUOTE]

yes the hammer drops. It fictions fine unloaded. But not when loaded.

It sounds like it FAILS the function check.

 

[Tylenator]

Disconnector spring in upside down? If this guy assembled it, I'd check that first in a heartbeat. I'd also swap out the notched hammer and unshrouded BCG (a trigger and NiBo BCG+hammer from the group buy would do quite well IMO.)

Here's a two part question...

1) which way is the disconnector spring supposed to be oriented? I've seen it both ways online which doesn't help me lol

2) if the hammer and disconnector work fine during an unloaded function check (which they do), I'd think that isn't the issue? It's only while shooting ammo the "catch" happens

 

[Tylenator]

No no, it doesn't fail. I charge it, it locks the hammer back. I pull the trigger (and keep holding it) and the hammer drops onto the firing pin. As I continue to hold the trigger and charge the weapon again simulating what it would be like shoot, I feel the trigger reset, I drop the bolt, release the trigger fully, and fire again. It passed.

 

[NateIU10]

Here's a two part question...

1) which way is the disconnector spring supposed to be oriented? I've seen it both ways online which doesn't help me lol

2) if the hammer and disconnector work fine during an unloaded function check (which they do), I'd think that isn't the issue? It's only while shooting ammo the "catch" happens

1) The fatter side should be inside the trigger, smaller side up pressing against the disconnector.

2) Not sure, but the forces during firing are different than manually charging, so it can't hurt to check.

What brand of lower is it? Do you know the brand of LPK?

 

[NateIU10]

What kind of ammo were you shooting? Was it low powered? Is the gas block aligned correctly? What weight buffer is in the rifle? GI buffer spring? It could be failing to reset because of any of those things, and instead of just getting normal hammer follow, you're having problems because of the unshrouded carrier and notched hammer.

Just spitballing here.

 

[Tylenator]

1) The fatter side should be inside the trigger, smaller side up pressing against the disconnector.

2) Not sure, but the forces during firing are different than manually charging, so it can't hurt to check.

What brand of lower is it? Do you know the brand of LPK?

It's a bushmaster lower. Not sure about LPK.

 

[Tylenator]

What kind of ammo were you shooting? Was it low powered? Is the gas block aligned correctly? What weight buffer is in the rifle? GI buffer spring? It could be failing to reset because of any of those things, and instead of just getting normal hammer follow, you're having problems because of the unshrouded carrier and notched hammer.

Just spitballing here.

Remington 223 target ammo. Gas block looked fine. I took it off and put it back on. Buffer specs unfortunately I don't know. I'm just gonna swap my buddy's lower with mine, and slowly integrate parts until it doesn't work.

 

[NateIU10]

Remington 223 target ammo. Gas block looked fine. I took it off and put it back on. Buffer specs unfortunately I don't know. I'm just gonna swap my buddy's lower with mine, and slowly integrate parts until it doesn't work.

Sounds like a good plan. Isolate parts until the issue arises. I'd still tend to think this is a disconnector problem, but you seem to have a good idea on where to go from here.

 

[Tylenator]

Sounds like a good plan. Isolate parts until the issue arises. I'd still tend to think this is a disconnector problem, but you seem to have a good idea on where to go from here.

I completely agree, disconnect gets my vote. I'll return with updates hopefully tomorrow evening or the next day.

 

[ColonelHurtz]

I'd bet on the disco. Easy part to replace.
But take the whole FCG apart and examine it for evidence that he started filing on the disco, hammer or trigger bearing surfaces. You may just have a botched "trigger job".
For <$50 you could put a whole new FCG in or pony up for a Geissele and be done with it.

 

[303_enfield]

Ok, without finger banging your rifle. The picture shows a magazine related failure, crush the mag.

Notched hammers suck! Replace LPK. Here $40:
http://palmettostatearmory.com/index.php/ar-15-05/lower-parts/palmetto-state-armory-classic-lpk.html

Next go here and take the old LPK out and reassemble it a couple of times.
http://www.ar15.com/forums/t_3_4/22...__GAS_BLOCK___Step_by_step_instructions_.html

I checked my one stock Bushy, no notched hammer in it.

What ammo are you using and did you clean the rifle first?

Good luck!

 

[BenL]

If the guy admitted to bubba'ing the trigger group, the first thing I'd do it take out the trigger/sear/hammer and toss it. I'll bet that will fix your problem.

 

[jrumann59]

Ok, without finger banging your rifle. The picture shows a magazine related failure, crush the mag.

Notched hammers suck! Replace LPK. Here $40:
http://palmettostatearmory.com/index.php/ar-15-05/lower-parts/palmetto-state-armory-classic-lpk.html

Next go here and take the old LPK out and reassemble it a couple of times.
http://www.ar15.com/forums/t_3_4/22...__GAS_BLOCK___Step_by_step_instructions_.html

I checked my one stock Bushy, no notched hammer in it.

What ammo are you using and did you clean the rifle first?

Good luck!

His picture is showing the BCG is not going into battery all the way, it stops just as it picks up the round, by the hammer not the round.

 

[303_enfield]

This:
"6. As the bolt is closing it "jams". The notch in the hammer is getting caught on the collar of the firing pin (I have an un-shrouded carrier) as the next live round sits loose, halfway loaded into the chamber."

Hammer is coming off the sear to get "caught". That is a safety feature so you don't wear your weapon. Take out the LPK and follow this link:
http://www.ar15.com/forums/t_3_4/22...__GAS_BLOCK___Step_by_step_instructions_.html

Reassemble it. An try again.
If nothing was filed on or taken out. You should be go to go. But I would get rid of the notched hammer ($15) then latter get a real bolt carrier (USGI $75-$100).

Either the builder put the LPK in wrong or somebody tried to save a $200 tax stamp.

Good luck!

 

[303_enfield]

His picture is showing the BCG is not going into battery all the way, it stops just as it picks up the round, by the hammer not the round.

Picture shows the bolt over the round. Two problems, one LPK assembled wrong or F'd with. Second bad mag. Again this is without touching the rifle.

 

[Russ D]

If you are close to Manchester bring it to me and I'll show you how the trigger group should be put together. I'll be home all evening.

 

[dist1646]

Sounds like a large collar M16 firing pin to me. Could be some other issues but I would have to take a look at it. I'm in Eldersburg, I could check it out for you if you want.