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Posted: 4/12/2014 12:51:35 PM EDT
[#1]
Quoted: Got out my nPAP for a good shake down at the range today. Previously I had fired a few rounds thru it in the winter and had a little problem cycling I figured due to it being new out of box and extremely cold with some thick cosmoline packed inside. So I stripped it down, cleaned it well and it has been waiting for spring. Enter Spring. Problem: Pull trigger fire, pull trigger nothing. I would have to pull the charging handle back, eject a round to fire again. Repeat every other round. Not good. I had put on a new Muzzle break and a friend suggested that the gas block was no longer building enough pressure to cycle the next round. So I removed the muzzle break and the results were much better. I"d get it to jam now about once every 10-15 rounds. Cause and effect. Problem is not solved. Is there something I can do to adjust the gas block to compensate? Thanks in advance. Is the trigger/hammer pins held in with a spring or plate? |
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Posted: 4/12/2014 1:17:19 PM EDT
[#2]
is your gas block canted? or small/obscured gas port. muzzle brake was lowering the recoil, making it harder for the bolt to go back, but it's a secondary problem
how easy is it to pull charging handle back if harder than usual - try to do it with bolt and without bolt installed - see it the bolt cams or the rails could be binding |
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Posted: 4/12/2014 2:25:12 PM EDT
[#3]
Quote HistoryQuoted:
Are the pins walking out of your trigger group? Is the trigger/hammer pins held in with a spring or plate? That shouldn't have any effect on the OP's problem aside from binding. OP, there could be a few things wrong: 1. Gas port is undersized or there is a burr in the port 2. Gas port is not drilled in the right place/gas block is not centered over the gas port 3. The gun is binding up enough at the piston and/or rails that it's causing sluggish operation |
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Posted: 4/12/2014 5:04:32 PM EDT
[#4]
Quote HistoryQuoted:
Are the pins walking out of your trigger group? I don't think so Is the trigger/hammer pins held in with a spring or plate? spring Quote HistoryQuoted:
Quoted:
Got out my nPAP for a good shake down at the range today. Previously I had fired a few rounds thru it in the winter and had a little problem cycling I figured due to it being new out of box and extremely cold with some thick cosmoline packed inside. So I stripped it down, cleaned it well and it has been waiting for spring. Enter Spring. Problem: Pull trigger fire, pull trigger nothing. I would have to pull the charging handle back, eject a round to fire again. Repeat every other round. Not good. I had put on a new Muzzle break and a friend suggested that the gas block was no longer building enough pressure to cycle the next round. So I removed the muzzle break and the results were much better. I"d get it to jam now about once every 10-15 rounds. Cause and effect. Problem is not solved. Is there something I can do to adjust the gas block to compensate? Thanks in advance. Is the trigger/hammer pins held in with a spring or plate? spring |
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Posted: 4/12/2014 5:10:22 PM EDT
[#5]
Quote HistoryQuoted:
is your gas block canted? or small/obscured gas port. muzzle brake was lowering the recoil, making it harder for the bolt to go back, but it's a secondary problem how easy is it to pull charging handle back if harder than usual - try to do it with bolt and without bolt installed - see it the bolt cams or the rails could be binding Handle seems to pull back just OK, I took the dust cover off and charged a little slowly and found the Carrier seems to hang up on the trigger group with the bolt in our out. See pics. Does this mean I have binding on the rails? 
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Posted: 4/12/2014 5:54:08 PM EDT
[#6]
Quote HistoryQuoted:
Handle seems to pull back just OK, I took the dust cover off and charged a little slowly and found the Carrier seems to hang up on the trigger group with the bolt in our out. See pics. Does this mean I have binding on the rails? <a href="http://s59.photobucket.com/user/toadwbg/media/AR15/20140412_200057.jpg.html" target="_blank">http://i59.photobucket.com/albums/g310/toadwbg/AR15/20140412_200057.jpg</a> <a href="http://s59.photobucket.com/user/toadwbg/media/AR15/20140412_200236.jpg.html" target="_blank">http://i59.photobucket.com/albums/g310/toadwbg/AR15/20140412_200236.jpg</a> Quote HistoryQuoted:
Quoted:
is your gas block canted? or small/obscured gas port. muzzle brake was lowering the recoil, making it harder for the bolt to go back, but it's a secondary problem how easy is it to pull charging handle back if harder than usual - try to do it with bolt and without bolt installed - see it the bolt cams or the rails could be binding Handle seems to pull back just OK, I took the dust cover off and charged a little slowly and found the Carrier seems to hang up on the trigger group with the bolt in our out. See pics. Does this mean I have binding on the rails? <a href="http://s59.photobucket.com/user/toadwbg/media/AR15/20140412_200057.jpg.html" target="_blank">http://i59.photobucket.com/albums/g310/toadwbg/AR15/20140412_200057.jpg</a> <a href="http://s59.photobucket.com/user/toadwbg/media/AR15/20140412_200236.jpg.html" target="_blank">http://i59.photobucket.com/albums/g310/toadwbg/AR15/20140412_200236.jpg</a> No, that's normal. Some US made semi FCG's have hammers that ride high and can hold the action open if you ride the bolt forward. It's only an issue if it happens when you are shooting the rifle or when you don't ride it forward. |
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Posted: 4/12/2014 7:00:17 PM EDT
[#7]
^^^+1
thats typical. I would think at this point - you have gas port issue - canted gas block or obscured gas port call manufacturer or if you have an access to a gunsmith, I would press the gas block out and inspect the gas port |
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Posted: 4/12/2014 7:28:04 PM EDT
[#8]
Quote HistoryQuoted:
^^^+1 thats typical. I would think at this point - you have gas port issue - canted gas block or obscured gas port call manufacturer or if you have an access to a gunsmith, I would press the gas block out and inspect the gas port I'm learning a lot here with your guys input and help of a parts diagram. Thanks guys, bear with me! I took the Upper hand-guard w/Gas cylinder off to take a look. All seems legit, see photos but I can't physically see all they way down the hole into the Gas Port block. getting the Gas Port Block off looks a little difficult. 
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Posted: 4/12/2014 7:31:04 PM EDT
[#9]
how does it cycle with the gas tube off?
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Posted: 4/12/2014 7:42:18 PM EDT
[#10]
Quote HistoryQuoted:
how does it cycle with the gas tube off? No different |
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Posted: 4/12/2014 7:44:22 PM EDT
[#11]
Closeup here of gas Block joint to Gas Cylinder/Handguard at the venting ports. Does this look normal?
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Posted: 4/12/2014 7:52:37 PM EDT
[#12]
Stuck a pipe cleaner down the hole- threads thru no problem.
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Posted: 4/12/2014 10:03:30 PM EDT
[#13]
It could also be having a hard time extracting the cartridge, making it short stroke. Did you get all of the cosmoline and any metal shavings out of the chamber? Check for burrs? Look at a spent case and see if it has any scratches or drag marks down the side of it.
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Posted: 4/12/2014 10:54:16 PM EDT
[#14]
The gas port on 45 deg. gas blocks are drilled with the block pinned in place so misalignment shouldn't be an issue. How is the fit between the gas block and piston. There should be very little slop between the two. This issue sometimes comes up with used rifle kits, not new rifles but you never know until you check.
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Posted: 4/13/2014 2:31:39 AM EDT
[#15]
Sounds like you have eliminated any problem with the gas port. How about trying different ammo and see if you still have the problem? Seems like I remember someone else with a similar problem, a gunsmith they knew told them to sit in front of the TV and cycle the action over and over. It helped break everything in, for them it worked.
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Posted: 4/13/2014 3:33:22 AM EDT
[#16]
1. Did you properly lubricate the rifle after you cleaned it? If not, do so before firing it again.
2. With the rifle empty, squeeze the trigger AND HOLD IT TO THE REAR. While holding the trigger, pull the operating handle to the rear and allow it to go forward slowly. Does the carrier bind when moving forward? If you release the operating handle does the carrier stay to the rear while the trigger is held to the rear? 3. The gas port should accept a 9/64ths drill bit shank. If yours doesn't the port is undersized. |
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Posted: 4/13/2014 7:21:45 AM EDT
[#17]
Any signs of carbon fouling around the inner area of the gas block and barrel? A bad seal in the gas system creating weak pressure?
The hammer bind can be normal depending on the FCG; as the poly said check the cycling with the trigger held in after firing. When firing the action will cycle faster than your trigger reset so the action will cycle when the disconnector is still holding the hammer down further and not the trigger sear. If your gas port is undersized, put a cleaning rod in the barrel before you drill it, that way your bit will hit the rod once you drill through and not ding up the opposite (bottom) side of your barrel. |
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Posted: 4/13/2014 7:04:29 PM EDT
[#18]
Responses to your great questions below:
Quote HistoryQuoted:
Any signs of carbon fouling around the inner area of the gas block and barrel? There was a little, now removed. A bad seal in the gas system creating weak pressure? See my pic above, should this seal be better around the bleed ports? The hammer bind can be normal depending on the FCG; as the poly said check the cycling with the trigger held in after firing. When firing the action will cycle faster than your trigger reset so the action will cycle when the disconnector is still holding the hammer down further and not the trigger sear. did this, it does cycle faster and smoother that way I can see why looking inside. If your gas port is undersized, put a cleaning rod in the barrel before you drill it, that way your bit will hit the rod once you drill through and not ding up the opposite (bottom) side of your barrel. |
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Posted: 4/13/2014 7:07:10 PM EDT
[#19]
Notes below in blue
Quote HistoryQuoted:
1. Did you properly lubricate the rifle after you cleaned it? If not, do so before firing it again. I did lubricate but maybe not well enough. 2. With the rifle empty, squeeze the trigger AND HOLD IT TO THE REAR. While holding the trigger, pull the operating handle to the rear and allow it to go forward slowly. Does the carrier bind when moving forward? No If you release the operating handle does the carrier stay to the rear while the trigger is held to the rear? It slides forward smoother with the trigger pulled all the way back, I can see why looking inside. 3. The gas port should accept a 9/64ths drill bit shank. If yours doesn't the port is undersized. |
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Posted: 4/13/2014 7:07:52 PM EDT
[#20]
Quote HistoryQuoted:
Sounds like you have eliminated any problem with the gas port. How about trying different ammo and see if you still have the problem? Seems like I remember someone else with a similar problem, a gunsmith they knew told them to sit in front of the TV and cycle the action over and over. It helped break everything in, for them it worked. I've had to do that with break-open shotguns ;) |
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Posted: 4/13/2014 10:38:09 PM EDT
[#21]
I'm wondering if some grease got in the gas port.....Use a hand held air jet and blow air into the gas port to see if you can dislodge whatever may be in there...After a normal cleaning I always use an air jet to do this on my guns....
Hope I works....Let us know whatever it is.... |
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Posted: 4/14/2014 3:28:38 AM EDT
[#22]
Quote HistoryQuoted:
Notes below in blue Can't measure without taking it completely off. I'm going to try and avoid that unless it's the last thing by process of elimination. Quote HistoryQuoted:
Notes below in blue Quoted:
3. The gas port should accept a 9/64ths drill bit shank. If yours doesn't the port is undersized. 1. You can insert the shank of a 9/64ths drill bit into the port with the block installed, provided the port is not undersized.. |
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Posted: 4/14/2014 2:20:03 PM EDT
[#23]
Quote HistoryQuoted:
1. You can insert the shank of a 9/64ths drill bit into the port with the block installed, provided the port is not undersized.. Quote HistoryQuoted:
Quoted:
Notes below in blue Quoted:
3. The gas port should accept a 9/64ths drill bit shank. If yours doesn't the port is undersized. 1. You can insert the shank of a 9/64ths drill bit into the port with the block installed, provided the port is not undersized.. will do If I need to. I got a caliper to measure it fairly accurately. |
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Posted: 4/14/2014 2:21:35 PM EDT
[#24]
Quote HistoryQuoted:
I'm wondering if some grease got in the gas port.....Use a hand held air jet and blow air into the gas port to see if you can dislodge whatever may be in there...After a normal cleaning I always use an air jet to do this on my guns.... Hope I works....Let us know whatever it is.... The pipe cleaner goes right thru the gas port with ease. After some further inspection there is a little carbon build up there- like a flake that i will try to get out with compressed air and maybe some water pressure if needed. |
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Posted: 4/14/2014 2:32:15 PM EDT
[#25]
This hasn't really been covered yet- the gaps at the front and rear of the Gas Cylinder. Each side seems to have a little gap, I can slide it one way or another to eliminate some gap on either end but will always have a little. There are also the bleed ports on the front.
Thoughts? 
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Posted: 4/14/2014 4:22:09 PM EDT
[#26]
Quote HistoryQuoted:
This hasn't really been covered yet- the gaps at the front and rear of the Gas Cylinder. Each side seems to have a little gap, I can slide it one way or another to eliminate some gap on either end but will always have a little. There are also the bleed ports on the front. Thoughts? /a> The gas tube just guilds the piston into the gas block. It would still function with a 1/4" gap. All the gas trapping is done by the piston head and the gas block. |
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Posted: 4/14/2014 6:08:42 PM EDT
[#27]
Quote HistoryQuoted:
The gas tube just guilds the piston into the gas block. It would still function with a 1/4" gap. All the gas trapping is done by the piston head and the gas block. Quote HistoryQuoted:
Quoted:
This hasn't really been covered yet- the gaps at the front and rear of the Gas Cylinder. Each side seems to have a little gap, I can slide it one way or another to eliminate some gap on either end but will always have a little. There are also the bleed ports on the front. Thoughts? /a> The gas tube just guilds the piston into the gas block. It would still function with a 1/4" gap. All the gas trapping is done by the piston head and the gas block. Gotcha, wasn't sure of that. Thanks. |
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Posted: 4/14/2014 6:46:53 PM EDT
[#28]
Measuring that gas port should be top priority. And if all else fails just open up the port some and that's a pretty safe bet it will function.
I wouldn't be concerned with grease or similar blocking the gas port, the amount of pressure blasting through their when the action cycles will clean anything temporary out. |
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Posted: 4/15/2014 6:41:33 AM EDT
[#29]
Quote HistoryQuoted:
will do If I need to. I got a caliper to measure it fairly accurately. Quote HistoryQuoted:
Quoted:
Quoted:
Notes below in blue Quoted:
3. The gas port should accept a 9/64ths drill bit shank. If yours doesn't the port is undersized. 1. You can insert the shank of a 9/64ths drill bit into the port with the block installed, provided the port is not undersized.. will do If I need to. I got a caliper to measure it fairly accurately. If a 9/64ths bit shank won't go in the port, I would buy a gas port reamer (it's really a cleaning tool for the gas port) and use that rather than trying to drill it out. |
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Posted: 4/27/2014 4:18:28 PM EDT
[#30]
Follow-up.
I buffed the rails, bottom of the bolt carrier group and top of the dis-connector on my nPAP and oiled it up good. I fired a 30-round mag and only had one hang-up. This was definitely and improvement and the 1-round hang-up could have been from something else. Thanks everyone for their assistance here! ARFcom does not disappoint! Next task: Mounting my Aimpoint 
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