2aHawaii
Tools and Uses => Firearms and Accessories => Topic started by: changemyoil66 on June 13, 2022, 08:59:29 AM
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Mrs.CMO's rifle shot about 200rds yesterday and she had about 4 light primer strikes. Federal XM193 was used in her and my rifle. I had no issues (Smith & Wesson M&P15). So I don't think it was the ammo, because I shout about 120rds from the same batch of ammo. This is the first time she has had this issue. She has probably about 3K rounds in 3 years maybe.
Her rifle was fully cleaned prior to shooting (BCG, chamber end, barrel, etc...). 1 guy at the range mentioned I need to oil the firing pin, which oddly enough, I didn't do this time, but I normally do. IDK this guy really, so IDK how accurate he is. Everything else was oiled normally.
I googled and stuff that came up was issues due to a new trigger installed wrong, new BCG, new buffer tube, etc... None of these apply since her rifle was g2g all this time. I found 1 post that mentioned to measure how much the firing pin protrudes, but I do not have the tool to do that.
When 1st building the rifle, the Elf trigger she had, had this issue. But it was every round had a light primer strike. We contacted Elf and Brian (owner) was the one who picked up the phone and he sent another one. It has worked fine all these years.
Thoughts? And could it be the firing pin oiling?
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Don't know anything about the Elf trigger, but I know if you (or someone) put the hammer spring in backwards, you can get light primer strikes. That's pretty common. Look up the Geissele video in installing the SSA trigger. Looks like the Elf is drop in trigger, so shouldn't be that.
Never heard of oiling firing pin.
Recommend trying to isolate variables. Make a list of what was changed then go back to known/trusted parts one by one and see if that helps. Check to see if things drift/move. Changing of springs can often lead to unintended issues.
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Don't know anything about the Elf trigger, but I know if you (or someone) put the hammer spring in backwards, you can get light primer strikes. That's pretty common. Look up the Geissele video in installing the SSA trigger. Looks like the Elf is drop in trigger, so shouldn't be that.
Never heard of oiling firing pin.
Recommend trying to isolate variables. Make a list of what was changed then go back to known/trusted parts one by one and see if that helps. Check to see if things drift/move. Changing of springs can often lead to unintended issues.
Haven't changed anything since the gun was built. I didn't get to clean her yet because we got home late, but I will in the next few days. I will double check to make sure nothing came loose.
1 post mentioned make sure the firing pin hole isn't gunked up with stuff, which I would have caught when assembling the BCG after cleaning.
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Haven't changed anything since the gun was built. I didn't get to clean her yet because we got home late, but I will in the next few days. I will double check to make sure nothing came loose.
1 post mentioned make sure the firing pin hole isn't gunked up with stuff, which I would have caught when assembling the BCG after cleaning.
Check the firing pin channel when cleaning, along with the firing pin hole in the bolt.
How long since you cleaned the chamber? Do you shoot combination of steel cased and brass?
One cheap check along the way is to try a new firing pin. That's not common, but cheap to take that off the list.
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Haven't changed anything since the gun was built. I didn't get to clean her yet because we got home late, but I will in the next few days. I will double check to make sure nothing came loose.
1 post mentioned make sure the firing pin hole isn't gunked up with stuff, which I would have caught when assembling the BCG after cleaning.
if it only started this range trip after cleaning, it's most likely a reassembly error...
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Check the firing pin channel when cleaning, along with the firing pin hole in the bolt.
How long since you cleaned the chamber? Do you shoot combination of steel cased and brass?
One cheap check along the way is to try a new firing pin. That's not common, but cheap to take that off the list.
I clean the chamber with the brush after every shoot. So 3 weeks ago would be the last time I did it with the chamber cleaner brush.
No steel ammo used.
I do have a spare firing pin somewhere in the home. I gotta look.
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if it only started this range trip after cleaning, it's most likely a reassembly error...
Wouldn't that cause malfunctions like all the time, not just 4 of 200rds?
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if it only started this range trip after cleaning, it's most likely a reassembly error...
Wow. . . #harshinghisvibe ;D
Intermittent light primer strikes are difficult to figure out. I can't think of a reassembly error that could lead to that though. Can only think of some rounds not going back into battery fully for intermittent. Castle nut backing out is common for builds.
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I clean the chamber with the brush after every shoot. So 3 weeks ago would be the last time I did it with the chamber cleaner brush.
SNIP
???
:rofl:
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???
:rofl:
Is this not supposed to be done this often? I do notice when inserting and pulling the chamber brush out, it's much more difficult to do than on my M&P15. Mrs. CMO has a Faxon pencil barrel.
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Wouldn't that cause malfunctions like all the time, not just 4 of 200rds?
true...
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Weak hammer strike most likely. Oiling the firing pin sounds like a good way to attract fouling and screw things up. Gunk around the firing pin could cause slam fires.
Keep it dry and make sure the pin slides freely.
Examine fired cases to see if the pin indentation is consistent.
Only time I had this was trying to use the light hammer spring in a JP trigger. Maybe 1 0ut or 6-7 would not fire first strike but would if run through again. Would not fire mil-surp 7.62mm ammo reliably, but .308 Win just fine. CMC triggers do so with authority and a lighter trigger pull..
Might have been a batch of ammo with hard primers?
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I'm pretty sure elftmann triggers are cassette style so cant really install wrong.
As for measuring the protrusion... Take the bolt out of the carrier and put it in a vise. Grab a caliper and rest it against the firing pin hole. (You gotta use the tail end of the caliper.. Meaning when you slide it to take measurements you'll see a rod on the opposite end of it stick out.)
So you rest the non moving part of the caliper (tail end side) against the lugs then push the part that moves against the firing pin hole. Then memorize or copy that number. With this in place...
push the firing pin in and you'll get your amount of protrusion by subtracting the first number by whatever the caliper says afterwards.
Id do it a couple of times to be sure.
I forgot what the exact amount is but Google it and you'll see.
As for oiling firing pin you can put a light film.
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Thanks for all the input. Due to the lack of tools, I'm gonna do the following:
1) Double check the BCG prior to cleaning to see if anything is blocking the firing pin
2) Examine the firing pin, compare it to mine, as I don't know what I'm really looking at without a side by side.
3) Use diff ammo for the next skill builder. Since this isn't as bad as every round getting a light strike, it would be very expensive to mag dump 200 more rounds. And it wasn't often enough to cause a huge problem or a huge concern if used for HD.
Also could it be the bolt not seating all the way in the chamber end? Like I mentioned when cleaning with the chamber brush, hers is very tight compared to mine. So maybe some kind of deformity/wear where the 2 meet that's preventing the perfect fit?
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Thanks for all the input. Due to the lack of tools, I'm gonna do the following:
1) Double check the BCG prior to cleaning to see if anything is blocking the firing pin
2) Examine the firing pin, compare it to mine, as I don't know what I'm really looking at without a side by side.
3) Use diff ammo for the next skill builder. Since this isn't as bad as every round getting a light strike, it would be very expensive to mag dump 200 more rounds. And it wasn't often enough to cause a huge problem or a huge concern if used for HD.
Also could it be the bolt not seating all the way in the chamber end? Like I mentioned when cleaning with the chamber brush, hers is very tight compared to mine. So maybe some kind of deformity/wear where the 2 meet that's preventing the perfect fit?
Yes, it could be, which is why I asked about cleaning the chamber. But you said you clean it all the time. To clarify, how do you brush the chamber? In a twist in/out motion? Or like a bore brush? Maybe all my ARs have same chamber, but I can't tell a difference. But yes, something causing the bolt to be slightly out of battery could lead to light primer strikes. I have just never had it happen on any of my guns. I've seen it on some guns where they were shooting a mix of steel and brass.
I have an extra caliper. LMK if you want to try it.
To clarify on firing pin. Yeah, slight coating of oil, or at least that's what I do. I've never heard of no oil causing problems, nor excessive lube. I prefer my BCG wet over dry. Cue sukebe comment from macsak ;D
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Yes, it could be, which is why I asked about cleaning the chamber. But you said you clean it all the time. To clarify, how do you brush the chamber? In a twist in/out motion? Or like a bore brush? Maybe all my ARs have same chamber, but I can't tell a difference. But yes, something causing the bolt to be slightly out of battery could lead to light primer strikes. I have just never had it happen on any of my guns. I've seen it on some guns where they were shooting a mix of steel and brass.
I have an extra caliper. LMK if you want to try it.
To clarify on firing pin. Yeah, slight coating of oil, or at least that's what I do. I've never heard of no oil causing problems, nor excessive lube. I prefer my BCG wet over dry. Cue sukebe comment from macsak ;D
I'm unable to do any twisting. So repeated in and out motion. Then use a q-tip with solvent on it until it's not dark black anymore. This takes about 5 Q-tips for each rifle. I'm pretty sure that there is no carbon in the Chamber because compared to a carbon build up on the side of the bolt that's just above the gas rings and not the star shape side, the Q-tip used on hard carbon still comes out black. For this end of the bolt, I use my dental pic. So this leads me to believe that there is no hard carbon stuck inside the chamber end. LMK if I'm wrong.
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I'm unable to do any twisting. So repeated in and out motion. Then use a q-tip with solvent on it until it's not dark black anymore. This takes about 5 Q-tips for each rifle. I'm pretty sure that there is no carbon in the Chamber because compared to a carbon build up on the side of the bolt that's just above the gas rings and not the star shape side, the Q-tip used on hard carbon still comes out black. For this end of the bolt, I use my dental pic. So this leads me to believe that there is no hard carbon stuck inside the chamber end. LMK if I'm wrong.
Chamber and bolt head are different zones.
Is this the chamber brush you are using?
https://www.amazon.com/Otis-Technology-FG-367-TP-Chamber-Brush/dp/B000E59A8E
Q-tip and dental picks? Bruh. . . ;D
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picks
Chamber and bolt head are different zones.
Is this the chamber brush you are using?
https://www.amazon.com/Otis-Technology-FG-367-TP-Chamber-Brush/dp/B000E59A8E
Q-tip and dental picks? Bruh. . . ;D
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Idk bout the chamber. I mean if its dirty then the round would not seat fully therefore it would be more of a peirced rimer than a light primer strike. Cause the round would not seat fully into the chamber.. Pushed more back towards the rear of the rifle.
If the bolt locks in the barrel extension id say it's good to go (cleanliness wise). Did ya headspace this build? It couldve been on the high end from the beginning. And now thousands of rounds later it's getting more sloppy?
Check the firing pin (circular part) where it hits the tail of the bolt.
As well as check the tail of the bolt itself. Look for any uniform abnormalities. Use a straight edge or a known flat surface and stand the bolt up by the end.
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Got a question CMO..
Was the bcg all the way home when you had light primer strikes?
Like if you pulled the trigger, then click... Did you look to see if the bcg was locked into the extension? Did ya tap the forward assist then rack it?
Were you able to pick up spent brass and compare the primers (the ones that went bang vs the LPS)?
Do ya have a set of calipers? Can do a OAL of firing pins.
.029-.036 is the range for a good firing pin.
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Chamber and bolt head are different zones.
Is this the chamber brush you are using?
https://www.amazon.com/Otis-Technology-FG-367-TP-Chamber-Brush/dp/B000E59A8E
Q-tip and dental picks? Bruh. . . ;D
Thata the one.
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https://www.youtube.com/watch?v=RP9o4OE8K1s
Like dis?
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Wow.(https://uploads.tapatalk-cdn.com/20220614/9fa8b08d9a6fe8b338a406ff35aa49b2.jpg)
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Wow.(https://uploads.tapatalk-cdn.com/20220614/9fa8b08d9a6fe8b338a406ff35aa49b2.jpg)
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Chinese made bolt....
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Here you go
https://palmettostatearmory.com/psa-5-56-nitride-mpi-full-auto-bolt-carrier-group-516446953.html
I can also get you a good deal on a Colt BCG. It will be at least 2x the PSA BCG above tho.
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Btw, what brand was that BCG? 3k rounds is light work for a bolt.
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She doesnt remember, but it wasnt name brand as its a rainbow colored BCG. She wants to keep the BCG, so im asking LGS if they just have a bolt for sale.
If none in stock, ill prob order a BCM bolt. Thoughts?(https://uploads.tapatalk-cdn.com/20220614/b33dd39e12013e72fb45b83e34a8bfe1.jpg)
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She doesnt remember, but it wasnt name brand as its a rainbow colored BCG. She wants to keep the BCG, so im asking LGS if they just have a bolt for sale.
If none in stock, ill prob order a BCM bolt. Thoughts?
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I think you should look more at function over looks… ;D
BCM BCGs are solid. I have a couple. Sometimes hard to find in stock tho.
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I think you should look more at function over looks… ;D
BCM BCGs are solid. I have a couple. Sometimes hard to find in stock tho.
Tell that to the woman. Im hoping it was just the weak bolt, as in no name BCG, which means no name componants (bolt).
So a name brand bolt prevents this from happening this soon.
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Tell that to the woman. Im hoping it was just the weak bolt, as in no name BCG, which means no name componants (bolt).
So a name brand bolt prevents this from happening this soon.
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You can just buy a bolt. I have one, maybe two BCM spare bolts. The bolt you posted is stamped MPI. $hit happens tho, but less often for a quality bolt. I’ve mostly seen the lugs get sheared off.
https://bravocompanyusa.com/bcm-ar15-bolt-assembly-mpi/
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Regarding elfman triggers, I no longer trust them. I have sent 2 to them twice and 1 was sent once. Their customer service and warranty is great but that doesn't do me any good when the trigger does not function 100% of the time. The last go around was during a class and I started getting light strikes, I had just gotten the trigger back from them..While it did allow me to practice malfunction drills it's a product I no longer have confidence in.
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Regarding elfman triggers, I no longer trust them. I have sent 2 to them twice and 1 was sent once. Their customer service and warranty is great but that doesn't do me any good when the trigger does not function 100% of the time. The last go around was during a class and I started getting light strikes, I had just gotten the trigger back from them..While it did allow me to practice malfunction drills it's a product I no longer have confidence in.
I just watched a YT video today that said the Elfman triggers that offer a lighter pull weight are notorious for causing light primer strikes. Makes sense. Weaker spring = less hammer force.
I saw the same on my G17 when I tried the lighter springs that came with my upgrade trigger. The striker just didn't have the force to pierce the thicker primers on the Fiocchi 9mm ammo I bought. My OEM spring has no problem with the ammo.
Are there primers with super-thin casings for these light-weight springs? If not, i have to wonder why the springs exist. ???
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Thanks to all those helped. I didn't realize that so many had an extra bolt. I got like 4 messages.
I had DCT order me a CMMG bolt becuase Mrs. CMO needs it by next Saturday if she gets into the HDF combo skill builder. David said he can get it by next week. And if not, she can borrow 1 of his bolts. He will also do the go/no go check. I could get it for cheaper online, but I want to support him since he did so much for the 2A (online registration, just to name 1 thing).
Since so many have extra bolts (a few have 2+), I call that a clue. So I ordered a BCM bolt, cam pin, and extractor/extractor spring set from BCM as well. IDK how long it will take to arrive. I have a firing pin somewhere at home because I bought 1 when I first got my AR thinking it would eventually break, which now I know is super rare. Funny thing is the plan was to put it inside my compartment I have on my Magpul butstock, but it doesn't fit. At least I can put an extra battery for the red dot in there and hex key for the red dot.
B4 I disassembled the BCG, I played with the firing pin and it made a click every time I pushed it to have it protrude out the other end. So I compared this to my M&P15 BCG and there's no click. I also had to push way harder compared to my M&P15 BCG firing pin.
The interesting thing will be to see if the new bolt fails so soon again. Because then we know it's another issue. But this failure took about 4-5 years. So I'll have to update everyone way later if it happens.
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Thanks to all those helped. I didn't realize that so many had an extra bolt. I got like 4 messages.
I had DCT order me a CMMG bolt becuase Mrs. CMO needs it by next Saturday if she gets into the HDF combo skill builder. David said he can get it by next week. And if not, she can borrow 1 of his bolts. He will also do the go/no go check. I could get it for cheaper online, but I want to support him since he did so much for the 2A (online registration, just to name 1 thing).
Since so many have extra bolts (a few have 2+), I call that a clue. So I ordered a BCM bolt, cam pin, and extractor/extractor spring set from BCM as well. IDK how long it will take to arrive. I have a firing pin somewhere at home because I bought 1 when I first got my AR thinking it would eventually break, which now I know is super rare. Funny thing is the plan was to put it inside my compartment I have on my Magpul butstock, but it doesn't fit. At least I can put an extra battery for the red dot in there and hex key for the red dot.
B4 I disassembled the BCG, I played with the firing pin and it made a click every time I pushed it to have it protrude out the other end. So I compared this to my M&P15 BCG and there's no click. I also had to push way harder compared to my M&P15 BCG firing pin.
The interesting thing will be to see if the new bolt fails so soon again. Because then we know it's another issue. But this failure took about 4-5 years. So I'll have to update everyone way later if it happens.
If you had a backup AR, then no worries. . . ;D
You get a pass. You invested in ammo for MOAR shooting, so :thumbsup:
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If you had a backup AR, then no worries. . . ;D
You get a pass. You invested in ammo for MOAR shooting, so :thumbsup:
I have a backup lower at least and ammo. Lots, well not like 20K lots, but enough ammo for constant training.
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Add a 5th friend who has a spare bolt and offered. Geezez.
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Please report if changing out the bolt solved the problem. Thanks
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Please report if changing out the bolt solved the problem. Thanks
New bolt came in to Danger Close, gonna pick it up tomorrow and run this saturday. Check the pic above, im sure it was the bolt. Or amazing coincidence.
When i pressed the firing pin with my finger on the broken bolt, there was a clicking sound. Once i changed it out, no clicking.
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Check if light strike rounds are properly sized. Sometimes ammo quickly produced, such as now days ammo crunch, is not correctly or accurately made.
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Check if light strike rounds are properly sized. Sometimes ammo quickly produced, such as now days ammo crunch, is not correctly or accurately made.
Too late, I fired them from my rifle. We are taking a skill builder on Sat and I will be running the same case of ammo (Federal XM193). For the last skill builder, we both ran the same ammo case and I had no light strikes. I'm pretty sure it was the cracked bolt. See above clicking reference.
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Too late, I fired them from my rifle. We are taking a skill builder on Sat and I will be running the same case of ammo (Federal XM193). For the last skill builder, we both ran the same ammo case and I had no light strikes. I'm pretty sure it was the cracked bolt. See above clicking reference.
Doh. No focus. That’s the bolt? Yeah. That’s probably the problem. Lol
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Doh. No focus. That’s the bolt? Yeah. That’s probably the problem. Lol
The bolt was pink/purple. It was ashamed to be in such an oppressed operating conditions. ;D
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The bolt was pink/purple. It was ashamed to be in such an oppressed operating conditions. ;D
(https://i.imgur.com/UpsgGhs.png)
#underpressure
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https://www.ar15.com/deals/deal.html?did=2314 (https://www.ar15.com/deals/deal.html?did=2314)
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Picked up the CMMG bolt today from DCT. And will run this saturday's skill builder. Didn't have a go/no go gauge, but got a spare BCG just in case.
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Go no go with cmmg bolt passed. Had to YT, i left the extractor spring thing in (no focus).then had to YT which end the plunger goes in and what direction.
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So what? New bolt/bcg solve the issue?
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So what? New bolt/bcg solve the issue?
Yup, no issues. Both new bolts passed the go/nogo test prior to shooting. So at least now I got a spare bolt. Was gonna get a spare BCG, but decided to save my money for a new CCW gun.
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Yup, no issues. Both new bolts passed the go/nogo test prior to shooting. So at least now I got a spare bolt. Was gonna get a spare BCG, but decided to save my money for a new CCW gun.
Spare bolt will likely get you pretty far. I've never seen a BCG fail, other than non-staked or poorly staked carrier screws/bolts backing out. Keep an eye out for sales, usually near holidays for spares.