View Full Version : Weapon fires during trigger re-set while dry firing.
I just recived my BCM midlength upper back from the gunsmith where a troy rail was installed. I have a BCM BCG and BCM Gun Fighter charging handle. During a functions check I pull the trigger, hold it to the rear, cycle the bolt and let the trigger move forward to dry fire again but the weapon "fires" when I release the trigger instead of resetting.
Was any work done to the lower? Did it do this before it was sent off to the gunsmith? If I had to guess, something is out of spec with the disconnector and it is releasing the hammer prior to the sear getting in place properly. This would have nothing to do with the upper.
ForTehNguyen
08-21-10, 09:10
what would happen if you fired live rounds with this? Visit from the ATF? :o
I'm with emt370... Nothing to do with the upper mods - its a fire control issue - something is out of spec or over worn causing the hammer to not properly hand off from disco to sear. Have a trigger job done? Using an adjustable trigger?
With what you're describing your rifle will double upon resetting the trigger if you fire it. Get it fixed before taking it to the range - have the fire control group inspected.
pilotguyo540
08-21-10, 13:32
If you separate your upper and lower you can look at your fire control group in better detail. If you SLOWLY release the hammer you will see a a small hook on top of the trigger. This is a small piece of stamped steel. When you hold the trigger down it will engage the hammer and stop the hammer from going forward. I am willing to bet the hook is sheared.
Who made your trigger group?
I would order a new trigger ASAP.
Guys, thanks for the quick replies. It is a stock LMT lower it has never been fired by me. I am sure LMT fired it. It has a standard GI trigger. I only mentioned the upper so every one had a complete picture.
There is a Phase5 bolt catch in the lower the standard cath was replaced.
I just took a few photos. I need to get to my lap top to upload them.
Here are three close up photos. I tried again to do a functions check. It did not do it every time with the upper off the lower. With the gun put together it did it fifteen times in a row.
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1327
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1326
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1325
unfortunately, you seem to have the type of bad luck i have. this could be any number of things, since you say it's unfired. could be something out of spec between the hammer and trigger sear points- one or both being too short, could be one or both of your pin holes are in the wrong spots. you could try replacing the FCG, but i think the lower should probably go back to LMT.
Do you have a spare FCG you can plop in and troubleshoot with? If not I would contact LMT on phone and let them handle it. Doubling is not a good thing
Don Robison
08-21-10, 16:35
Check the dis-connector spring and make sure it's installed properly. That is the usual suspect I start with for this type of problem; especially if it's a new unfired build.
i don't think it's a disconnect issue.. he says it drops on re-set. that would indicate the disconnect is the only part that's actually working. if the hammer and trigger sears are where they're supposed to be, the hammer would catch upon release of the disconnect via the trigger.
if the disconnect spring was jacked, the problem would be a failure to disconnect the hammer from action- the hammer would just ride the carrier back up upon cycling.
pilotguyo540
08-21-10, 17:36
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I had the same problem, its the hammer or the trigger or both. If either is worn a lil bit this happens. I replaced both. It slamfires 3-6 rnds an then jams. It can set off a round before its fully chambered, thats bad very bad risk of blowing up the gun.
I had the same problem, its the hammer or the trigger or both. If either is worn a lil bit this happens. I replaced both. It slamfires 3-6 rnds an then jams. It can set off a round before its fully chambered, thats bad very bad risk of blowing up the gun.
it's actually extremely unlikely to OBD on you.... and the only reason i say "extremely unlikely" instead of "impossible" is because of ol' Murphy. the first thing to make contact with anything else is the bolt face against the BE.. as the carrier continues forward, hammer pressing it or not, the bolt immediately begins to lock. by the time the carrier is far enough forward for the hammer to press against the firing pin enough to drive it into the primer, the bolts already mostly, if not fully, locked up.
not to de-rail, but i just wanted to point that out.
Here is my problem child.
https://www.m4carbine.net/picture.php?albumid=279&pictureid=1331
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Here are the photos you asked for hopefully something helps.
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1337
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1332
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1336
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1335
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1334
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1333
It is on reset. I was waiting for that farmiliar click re-set so I could pull the trigger again and was surprised to hear it "fire."
I will give LMT a call Monday.
i don't think it's a disconnect issue.. he says it drops on re-set. that would indicate the disconnect is the only part that's actually working. if the hammer and trigger sears are where they're supposed to be, the hammer would catch upon release of the disconnect via the trigger.
if the disconnect spring was jacked, the problem would be a failure to disconnect the hammer from action- the hammer would just ride the carrier back up upon cycling.
Robb Jensen
08-21-10, 21:23
I just recived my BCM midlength upper back from the gunsmith where a troy rail was installed. I have a BCM BCG and BCM Gun Fighter charging handle. During a functions check I pull the trigger, hold it to the rear, cycle the bolt and let the trigger move forward to dry fire again but the weapon "fires" when I release the trigger instead of resetting.
Typically a bad disconnector spring or bad disconnector.
If someones monkey'ed with the trigger and or hammer trying to smooth things out this can cause this too.
Don Robison
08-21-10, 22:03
i don't think it's a disconnect issue.. he says it drops on re-set. that would indicate the disconnect is the only part that's actually working. if the hammer and trigger sears are where they're supposed to be, the hammer would catch upon release of the disconnect via the trigger.
if the disconnect spring was jacked, the problem would be a failure to disconnect the hammer from action- the hammer would just ride the carrier back up upon cycling.
If the spring is turned 90 degrees and the end top coil is being pinched between the trigger and disconnect it will hold until the trigger is released and then drop the hammer. I've seen it in a number of guns. The last one was my own.:o
I bought it from G&R about a year ago and it has been in the safe since. I was going to use the lower for a form one SBR. Instead I went the form four route twice and wanted to keep this lower for a non SBR.
I think the dude who worked on my upper put a spell on my whole gun :p! Just kidding.
I've not fired a round. The only thing changed in the lower was the addition of a Phase5 EBRv2 Extended Bolt Release.
http://www.brownells.com/1/1/47018-ar-15-m16-extended-bolt-release-ebrv2-extended-bolt-release-phase-5-tactical.html
Typically a bad disconnector spring or bad disconnector.
If someones monkey'ed with the trigger and or hammer trying to smooth things out this can cause this too.
Robb Jensen
08-22-10, 08:10
I bought it from G&R about a year ago and it has been in the safe since. I was going to use the lower for a form one SBR. Instead I went the form four route twice and wanted to keep this lower for a non SBR.
I think the dude who worked on my upper put a spell on my whole gun :p! Just kidding.
I've not fired a round. The only thing changed in the lower was the addition of a Phase5 EBRv2 Extended Bolt Release.
http://www.brownells.com/1/1/47018-ar-15-m16-extended-bolt-release-ebrv2-extended-bolt-release-phase-5-tactical.html
That thing looks bone dry you might try adding some oil to the disconnector and spring and each end of the hammer and trigger pins right through their springs.
It is bone dry. Man that would be awesome if that is all she needed. On my way to get my oil.
Just hit the lower and upper with some Tettra oil and grease. It needed it. It is still doing the same thing. Is it called doubling?
Robb Jensen
08-22-10, 08:33
Just hit the lower and upper with some Tettra oil and grease. It needed it. It is still doing the same thing. Is it called doubling?
No doubling is essentially when the rifle fires two and is cause by worn sear engagement between the hammer and the trigger. You're is a bad disconnector or warn disconnector spring releasing the hammer too soon before trigger is all the way back up with enough sear engagement to hold the sprung hammer.
Ok LMT Rocks. I had an email response first thing this morning offering to have me ship it back for a look. After a few emails I was told to email my serial number and address for replacement parts. Thanks LMT. I will let you guys know the outcome.
LMT came through, the parts arrived mid week. I brought them to my local gun shop and one of the guys put them in for me yesterday.
She really wants me to shoot her!
https://www.m4carbine.net/picture.php?albumid=279&pictureid=1363
The first time I tried a functions check it fired on reset. It was then good to go for ten or so functions checks now it is doing it again consistently. It does not matter who is doing the functions check, it fires on reset. Looks like I will be sending it back to LMT.
Here is a photo of what we removed from the gun.
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1362
ohiorifleman
09-11-10, 07:57
So LMT just sent a disconnecter and spring to replace not the entire FCG.
If that is the case I would have them send you a new hammer and trigger with springs- surely that would solve it unless the holes in your lower are out of spec..
I had the same thing happen on a DD LPK recently and I have a lot of spare parts lying around and was able to deduce it was an improperly ground hammer notch causing this exact same issue. DD did replace the parts no problem.
https://www.m4carbine.net/picture.php?albumid=278&pictureid=1362
pfff...
I will give LMT another call. Round trip shipping will cost me almost what a LPK would. The 17 year old kid who helped me out at the gun shop said he thought is was the trigger too. It sounds like time to replace it all.
Thanks guys.
So LMT just sent a disconnecter and spring to replace not the entire FCG.
If that is the case I would have them send you a new ham
mer and trigger with springs- surely that would solve it unless the holes in your lower are out of spec..
I had the same thing happen on a DD LPK recently and I have a lot of spare parts lying around and was able to deduce it was an improperly ground hammer notch causing this exact same issue. DD did replace the parts no problem.
Robb Jensen
09-11-10, 08:44
Or it's a great time to get a Geissele SSA trigger ! ;)
polymorpheous
09-11-10, 08:46
I was going to use the lower for a form one SBR. Instead I went the form four route twice and wanted to keep this lower for a non SBR.
I guess this illustrates why you should fire at least 1,000 rounds through a lower you plan to SBR to make sure it is GTG.
OP, I hope LMT takes care of this for you.
It looks like it wants to be a good shooter for you.
;)
pilotguyo540
09-11-10, 10:07
Or it's a great time to get a Geissele SSA trigger ! ;)
+1 I love mine!!! Everyone who fires it says, and I quote, "Holy shit!." That's what they say because it is that nice.
Or it's a great time to get a Geissele SSA trigger ! ;)
Is this what you guys are suggesting?
http://www.bravocompanyusa.com/Geissele-AR15-Super-Semi-Automatic-Trigger-p/geissele%20ssa%20trigger%20spin.htm
Looks like without the adjustment screws the "reliability" concerns are not an issue.
Damn this is gonna get expensive. :D
Robb Jensen
09-11-10, 13:34
Is this what you guys are suggesting?
http://www.bravocompanyusa.com/Geissele-AR15-Super-Semi-Automatic-Trigger-p/geissele%20ssa%20trigger%20spin.htm
Looks like without the adjustment screws the "reliability" concerns are not an issue.
Damn this is gonna get expensive. :D
Yep very reliable. And the hammer hits as hard or even harder than stock.
Very true.
I guess this illustrates why you should fire at least 1,000 rounds through a lower you plan to SBR to make sure it is GTG.
OP, I hope LMT takes care of this for you.
It looks like it wants to be a good shooter for you.
;)
Out of curiousity do you have another AR? If so, I would remove the entire FCG and swap them out and see if it happens. There is a possibility that the lower is out of spec.
I would also talk to them about reimbursement for the shipping costs as well.
I will give LMT another call. Round trip shipping will cost me almost what a LPK would. The 17 year old kid who helped me out at the gun shop said he thought is was the trigger too. It sounds like time to replace it all.
Thanks guys.
That is a good idea Gunz. I actually have another LMT it is the SBR I bought from G&R instead of doing a form one on this lower. The serial numbers of both lowers are less than fifty apart. I am waiting for uncle ATF to approve my BCM lower.
I emailed LMT today to ask for a new trigger, hammer and springs. I
Blankwaffe
09-11-10, 19:54
Out of curiousity do you have another AR? If so, I would remove the entire FCG and swap them out and see if it happens. There is a possibility that the lower is out of spec.
I would also talk to them about reimbursement for the shipping costs as well.
IG,
Couldn't a long grip screw,or short shelf inside the grip cause this situation as well?
I left it at work today or I would be trying the grip screw right now. I have a few spares and Q2 grips. It came with an Ergo.
I was just in pueblo yesterday finishing up the magpul class and my rifle which I had about 4000 rounds through it started doing that exact thing on the first drill during rifle zero confirmation! I was so freakin pissed off. Luckily I brought a LPK for another build I never started and with the help of a very knowledgeable guy at the class was able to fix it by replacing the trigger. We tried replacing the disconnector first, still did it, then the spring with the same problem. after the trigger swap it ran flawlessly for the entire 2000 rounds of the 3 day class. hope this helps and good luck
It does help. Thanks.
This is why I like this site so much folks are helpful and knowledgeable and willing to share & teach. A LPK just became tops on my list of spare parts list.
I wouldn't think so. But, I have never explored this issue in that manner.
IG,
Couldn't a long grip screw,or short shelf inside the grip cause this situation as well?
The lower was returned to me by mail today, there was not round trip mail charge. I paid to ship it in and they sent it back UPS. The problem is fixed. Gene from LMT replaced the entire fire control group and test fired it on 6 different uppers he had. I did a functions check and she is good to go.
So was the issue the LPK?
The lower was returned to me by mail today, there was not round trip mail charge. I paid to ship it in and they sent it back UPS. The problem is fixed. Gene from LMT replaced the entire fire control group and test fired it on 6 different uppers he had. I did a functions check and she is good to go.
IG
I asked LMT what the issue was. They said they replaced the entire fire control group and the issue was solved. I never did change out the parts myself. I plan to add a LPK to my spare parts.
There is a Phase5 bolt catch in the lower the standard cath was replaced.
Heh...that's quite a suite of malware that Phase 5's website tries to put on your computer.
I asked LMT to put my old bolt catcih back in for me. The phase 5 was way too bigm I want smiths BAD lever.
What program are you running that caught the mailware? I did not see it.
I asked LMT to put my old bolt catcih back in for me. The phase 5 was way too big I want another BAD lever.
What program are you running that caught the mailware? I did not see it she I was on their site. I also ordered by phone.
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