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Posted: 4/1/2010 2:54:24 PM EDT
[#1]
You could always get some extra power hammer springs.
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Posted: 4/1/2010 2:55:48 PM EDT
[#2]
Check firing pin and firing pin hole in the bolt. Make sure the tip looks good and bolt hole is clear. There is a protrusion gauge for truly checking this, but if you're familiar enough you can tell by looking. Assemble BCG, collapse bolt and push firing pin forward. You're looking for like 0.027" of protrusion or so, IIRC. I'll have to go look it up.
If this is correct, then either you have a weak hammer spring or more likely, the legs on the hammer spring aren't installed correctly. Not trying to pick at you - just a common problem and I've even done it myself before when not paying attention. |
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Posted: 4/1/2010 2:58:02 PM EDT
[#3]
Quoted:
You could always get some extra power hammer springs. Yeah, but why should I need an extra power hammer spring? I'm shooting Wal-mart 100 round box Federal .223 and half a dozen different kinds of .22lr. Out of 60 rounds of the Federal .223 I got 7 failures to fire. 6 of the 7 fired on the second try. Almost all of the .22lr fired after a second try. AV1611 out..... |
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Posted: 4/1/2010 3:07:24 PM EDT
[#4]
I agree 100% no need at all for extra power hammer spring shooting commercial fodder. The lightweight JP springs in my Wilson UT-15 ignite all primers, from commercial to all brands of M193, M855, etc. Still doesn't totally rule out a weak standard spring though, even if new.
I'm sticking to most likely cause as a bad firing pin. It could be a bad bolt too as well though (hope not - more $$$, plus, never seen a bad Bushy bolt in terms of dimensions and often they are CMT I think). Do what I said above with the bcg and look for like 0.025-0.035" (somewhere in that ballpark - don't recall the upper limit for pierced primers but you obviously aren't there). If you have a set of feeler gauges you can use to "set" your eye before looking that would help - if not use a spark plug gauge to "calibrate" your eye. Hope this helps. |
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Posted: 4/1/2010 4:27:58 PM EDT
[#5]
Yeah I would triple check the hammer spring. Either make sure it's not on backwards, or make sure the legs are resting on the trigger pin.
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Posted: 4/1/2010 5:02:17 PM EDT
[#6]
Moved to troubleshooting forum
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Posted: 4/1/2010 7:06:14 PM EDT
[#7]
Look carefully at the winds of the springs and where the end of the hammer spring legs are resting. On the hammer, confirm that the J spring is not sticking out the bottom of the hammer, and binding up on the front void of the receiver cavity. With the trigger pulled back, work the hammer full range and confirm that the bottom lob of the hammer is not making contract with the front of the trigger, and it too slowing down the hammer stroke as well. Also. confirm that you have lubed the FCG including the pins and that both the hammer and trigger both move freely on the pins. Firing pin protrusion for 223/5.56 nato is .032 to .037 for in spec when the FP is maxed inward on the back of the bolt. You can use the tail end of any caliper to check the protrusion. Harbor freights sells both dial and digital calipers for under $20 and will find uses for it beside this project alone. 
As for the 22lr kit, what brand and has it been polished???? With the problem on both the kit and in 223, I leads me to believe that the problem is hammer speed, but could be a bit of something else going on here, such at both the 223 and 22lr not locking up correctly, and the problem at hand (read poly coated ammo or the rifle not being cleaned/lubed correctly for such, and the kit not polished and having problems on it's own independent problems of it own. |
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Posted: 4/2/2010 5:09:23 AM EDT
[#8]
Quoted:
http://img.photobucket.com/albums/v503/AR15forme/IMG_5660.jpg Look carefully at the winds of the springs and where the end of the hammer spring legs are resting. On the hammer, confirm that the J spring is not sticking out the bottom of the hammer, and binding up on the front void of the receiver cavity. With the trigger pulled back, work the hammer full range and confirm that the bottom lob of the hammer is not making contract with the front of the trigger, and it too slowing down the hammer stroke as well. Also. confirm that you have lubed the FCG including the pins and that both the hammer and trigger both move freely on the pins. Firing pin protrusion for 223/5.56 nato is .032 to .037 for in spec when the FP is maxed inward on the back of the bolt. You can use the tail end of any caliper to check the protrusion. Harbor freights sells both dial and digital calipers for under $20 and will find uses for it beside this project alone. http://www.tresnainstrument.com/images/how_to_read_a_dial_caliper/how_to_use_a_dial_caliper_clip_image038_0000.jpg As for the 22lr kit, what brand and has it been polished???? With the problem on both the kit and in 223, I leads me to believe that the problem is hammer speed, but could be a bit of something else going on here, such at both the 223 and 22lr not locking up correctly, and the problem at hand (read poly coated ammo or the rifle not being cleaned/lubed correctly for such, and the kit not polished and having problems on it's own independent problems of it own. I'll crack open my AR later this morning and compare it to your picture. Thanks for that by the way. I'm running a CMMG .22lr conversion kit. I haven't taken a dremel polishing wheel to the guide rails on the .22 kit, but I do keep them lubed with Castrol full synthetic. I do get stove pipes on ejection once in a while. That tells me that either that round was weak (doubtful as this happens while using good ammo... Winchester Super X and CCI Mini Mags) or maybe the rails aren't smooth enough. AV1611 out.... |
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Posted: 4/2/2010 6:04:57 AM EDT
[#9]
Can you shake your carrier and hear the firing pin rattling around? Sometimes dirty ammo causes the inside of the carrier/bolt to muck up.
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Posted: 4/2/2010 1:05:03 PM EDT
[#10]
If the springs are good, try a heavier buffer. An H or spikes T2. I had this problem & my upper was over gassed a little. I had bolt bounce. An H2 buffer solved it. 100% reliable now.
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Posted: 4/3/2010 7:59:48 AM EDT
[#11]
Quoted:
Quoted:
http://img.photobucket.com/albums/v503/AR15forme/IMG_5660.jpg Look carefully at the winds of the springs and where the end of the hammer spring legs are resting. On the hammer, confirm that the J spring is not sticking out the bottom of the hammer, and binding up on the front void of the receiver cavity. With the trigger pulled back, work the hammer full range and confirm that the bottom lob of the hammer is not making contract with the front of the trigger, and it too slowing down the hammer stroke as well. Also. confirm that you have lubed the FCG including the pins and that both the hammer and trigger both move freely on the pins. Firing pin protrusion for 223/5.56 nato is .032 to .037 for in spec when the FP is maxed inward on the back of the bolt. You can use the tail end of any caliper to check the protrusion. Harbor freights sells both dial and digital calipers for under $20 and will find uses for it beside this project alone. http://www.tresnainstrument.com/images/how_to_read_a_dial_caliper/how_to_use_a_dial_caliper_clip_image038_0000.jpg As for the 22lr kit, what brand and has it been polished???? With the problem on both the kit and in 223, I leads me to believe that the problem is hammer speed, but could be a bit of something else going on here, such at both the 223 and 22lr not locking up correctly, and the problem at hand (read poly coated ammo or the rifle not being cleaned/lubed correctly for such, and the kit not polished and having problems on it's own independent problems of it own. I'll crack open my AR later this morning and compare it to your picture. Thanks for that by the way. I'm running a CMMG .22lr conversion kit. I haven't taken a dremel polishing wheel to the guide rails on the .22 kit, but I do keep them lubed with Castrol full synthetic. I do get stove pipes on ejection once in a while. That tells me that either that round was weak (doubtful as this happens while using good ammo... Winchester Super X and CCI Mini Mags) or maybe the rails aren't smooth enough. AV1611 out.... I opened up my AR last night and the trigger spring and hammer spring are installed correctly. The hammer just doesn't feel like it's under a ton of tension, though. Also, I took out the bolt and bolt carrier and tried giving them a shake. They definitely do NOT rattle around while shaking. Gunked up? If so, what should I use? Break cleaner? I've been having the problem with light primer strikes with both the .22lr CMMG conversion kit and with .223 since day one when everything was freshly cleaned and lubed. AV1611 out...... |
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Posted: 4/3/2010 8:39:20 PM EDT
[#12]
Quoted:
The hammer just doesn't feel like it's under a ton of tension, though. AV1611 out...... Try another hammer spring. Could be that you have a reduced tension spring in play, and it the problem at hand. Also, I took out the bolt and bolt carrier and tried giving them a shake. They definitely do NOT rattle around while shaking. Gunked up? If so, what should I use? Break cleaner? I've been having the problem with light primer strikes with both the .22lr CMMG conversion kit and with .223 since day one when everything was freshly cleaned and lubed.
Pull the bolt off the carrier, use the FP to punch out the extractor pin while removing the tension from the extractor, then with some CLP allowed to soak in the bolt FP channel, chase the FP channel with a Q-tip with some cotton removed from the end of it. |
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Posted: 4/8/2010 8:02:04 PM EDT
[#13]
Was this problem ever solved?
I just took a brand new LMT Defender lower mated to a brand new LMT 14.5" upper with LMT auto BCG out for the first time today. Was sighting in 4 other rifles and in a bit of a hurry, so I just put the LMT away and went to the next rifle. I forgot to check the primer strikes on the rounds that did fire (probably wouldn't have known which empties they were, there was brass all over the place). The problem was intermittent, but the rounds that did not fire were super light stikes, barely visable. I averaged a light strike about 1 out of 3-4 rounds fired. Ammo used was M855PD as well as Radway. No issues with the ammo in any of the other rifles and the PD was carefully inspected when it was purchased about 5 years ago. I'm thinking it's in the BCG...but I'll take her down over the weekend, got a cleanfest ahead of me. Curious what the culprit was with the OP. |
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Posted: 4/10/2010 6:41:01 AM EDT
[#14]
One thing I forgot to report in the initial post: I'm using KNS pins because there was a problem with pins walking out. For some reason the legs of the hammer spring don't fit down in the grooves to keep the pins from walking. I think the trigger pivot pin wasn't ground down properly (DPMS LPK). That wouldn't affect light strikes though, would it???
AV1611 out...... |
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Posted: 5/9/2010 6:27:26 AM EDT
[#15]
Something of a bump.
Was troubleshooting the new rifle I put together. Had 4 light primer strikes out of 180 rounds. Hammer spring was on backwards. Thanks for the photo above to clear it up. |
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