AR15.Com Archives
 Safety Preventing Firing- 2 Stage NM Trigger
Auxilio_ab_alto  [Member]
10/26/2011 8:29:48 PM
I am in the process of building an AR 15. I've purchased the following:
DPMS Stripped Lower Receiver from gun show
Fulton Armory Lower Receiver Parts Kit w/ 2 Stage NM Trigger -I believe I've identified the trigger as being from Rock River Arms, although FA doesn't say it.
Buffer Spring-Rifle, Buffer Tube-Rifle, Buffer-Rifle
Magpul PRS -purchased from Amazon
Fulton Armory Liberator Rifle Complete Upper -should arrive in about 3 weeks

I've assembled the Lower according to guides I've found on this site and the videos on Brownells. When I attempt the function test to make sure that my hammer releases when I pull the trigger (with the safety/selector in and in the fire position), it does not release. If I remove the safety, then pull the trigger, the hammer releases properly. Therefore, I believe the safety needs to be "fitted" to my rifle.

I asked Fulton Armory about it, and they said to send it in and they would take a look at it (they would charge $25 to look at it, $40 in shipping, plus I have to pay to ship it there, plus the cost of any replacement costs etc). I didn't like all those fees, or the idea of shipping it to Maryland, when they're already taking 3 weeks to build the upper. Who knows how long it might take to ship it to them, wait for them to look at it, then for them to ship it back. Maybe I'm a bit impatient. Fulton wouldn't make an assessment about what was wrong, and therefore they wouldn't tell me what I should do to fix it myself.

I took it to a local gun shop and they agreed with my assessment about the safety needing to be fitted, and they said they could fix it. However, they would prefer I bring them all the parts (including my Upper that I've purchased from Fulton Armory, but hasn't come in yet) when they attempt to fit the trigger, so that they could assemble it and test fire it. I'd rather build the rifle myself (this is my first time building a rifle and I want to understand how it works and therefore I want to put it together myself). I wouldn't mind if they just fitted the trigger/safety, but they're not willing to only do that. It'll be 3 weeks before my Upper comes in, and then it would take the local gun shop another 3 weeks to fit the safety/trigger and finish assembling. I'm unwilling to wait six weeks from now for what (I assume) should be a simple procedure of fitting it.

Therefore, I think I'll just have to fit the trigger myself. According to forums I've found on the Internet, it's a simple matter of just grinding down the safety/fire selector a bit. I'm unsure of the best way to go about this, and I want to make sure I do it properly since I'm modifying the part and not just assembling pre-made parts. Should I take a metal file and just grind down on the bottom of the safety until it has enough room to release? Since I assume I'm grinding away the anodized coating (I'm not a metallurgist), what would be the best way to protect the grinded down area? Any other tips for grinding it down?
Dano523  [Moderator]
10/26/2011 9:01:46 PM
Show me a photo of the parts installed, the hammer cocked back, then the trigger fully pulled with the hammer not releasing.

A non adjustable NM trigger, nor selector should need to be fitted to work correctly.

So either the parts are out of spec, or you installed something wrong.
Auxilio_ab_alto  [Member]
10/26/2011 9:52:39 PM
Originally Posted By Dano523:
Show me a photo of the parts installed, the hammer cocked back, then the trigger fully pulled with the hammer not releasing.

A non adjustable NM trigger, nor selector should need to be fitted to work correctly.

So either the parts are out of spec, or you installed something wrong.


How about a quick video?
http://www.youtube.com/watch?v=_z4Oc8wSjwk

I fully press the trigger. I realize I didn't install the pistol grip, safety detent spring etc for this video. But the effect is the same with or without those parts.
GSPatton  [Team Member]
10/26/2011 10:14:33 PM
Check out Figure 4 in this .pdf from Geiselle: http://0323924.netsolstores.com/pdfs/Hi-Speed-Instructions.pdf

I had the same problem with a Geiselle trigger and an Armalite LPK. You likely need to increase the width of the notch in the safety so that the trigger can pivot up into it. Take the trigger out of the rifle and see if it fits in that notch.

I used a hacksaw and cut a nice slot in the safety, then used a file to remove what was left. A dremel with the metal cutting disk would probably be a bit easier though, and is the method recommended by Geiselle.
Make sure you just remove metal to make it wider... not deeper.
458winmag  [Team Member]
10/26/2011 10:35:38 PM
Reluctantly I agree Hack saw not recommended
When possible you should let the supplier fix the problem. It takes you out of the gun lumber arena of you Effed it up and now it's your issue
Auxilio_ab_alto  [Member]
10/26/2011 10:51:44 PM
Originally Posted By GSPatton:
Check out Figure 4 in this .pdf from Geiselle: http://0323924.netsolstores.com/pdfs/Hi-Speed-Instructions.pdf

I had the same problem with a Geiselle trigger and an Armalite LPK. You likely need to increase the width of the notch in the safety so that the trigger can pivot up into it. Take the trigger out of the rifle and see if it fits in that notch.

I used a hacksaw and cut a nice slot in the safety, then used a file to remove what was left. A dremel with the metal cutting disk would probably be a bit easier though, and is the method recommended by Geiselle.
Make sure you just remove metal to make it wider... not deeper.


My safety is wide enough. The trigger fits into the notch. The problem is that it doesn't seem deep enough. There's not enough room for it to release from the safety. I feel like I would need to grind away the "core" of it so that there's enough room to release fully. In fact, it goes through the first stage. Just not the second stage. I made another video, hopefully it makes it a little easier to understand.
http://www.youtube.com/watch?v=LVXBAzFlk6U

I had found several threads on various forums with similar issues. Here's one from this site:
http://www.ar15.com/archive/topic.html?b=3&f=66&t=359604

Could the problem actually be that the hole for my safety is too far forwards, and that's why the selector blocks the second stage? If so, is there anything I can do for that? Or would just making the safety deeper still solve it?

In other news, I can't find a handy installation guide from RRA for the trigger. I wish they would do what Geiselle does and release some documentation.
Auxilio_ab_alto  [Member]
10/26/2011 10:54:25 PM
Originally Posted By 458winmag:
Reluctantly I agree Hack saw not recommended
When possible you should let the supplier fix the problem. It takes you out of the gun lumber arena of you Effed it up and now it's your issue


The supplier of the selector wants a minimum of $65 to even take a look, not to mention several weeks of waiting. Like I said in the post I just made, the problem could be with the lower in that the fire selector hole is too far forward.
458winmag  [Team Member]
10/26/2011 11:27:07 PM
You know what to do now
Auxilio_ab_alto  [Member]
10/26/2011 11:43:13 PM
Originally Posted By 458winmag:
You know what to do now


I do?
If I'm supposed to make the fire selector deeper, then how do I protect the metal? The newly exposed part wouldn't be anodized right?
eric10mm  [Team Member]
10/26/2011 11:50:59 PM
If all the LPK parts and FCG parts came from one supplier, I'd get on the horn with them for WARRANTY replacements.

If they won't solve your problem, shout it from the mountain tops!

ETA: Are you sure your lower is in-spec enough to work? Have you tried installing regular FCG parts and testing them?
Auxilio_ab_alto  [Member]
10/27/2011 12:00:15 AM
Originally Posted By eric10mm:
If all the LPK parts and FCG parts came from one supplier, I'd get on the horn with them for WARRANTY replacements.

If they won't solve your problem, shout it from the mountain tops!

ETA: Are you sure your lower is in-spec enough to work? Have you tried installing regular FCG parts and testing them?


No, I'm not 100% sure about the lower being mil-spec. My original intention was to purchase a mil-spec lower, but I guess I may have messed up. Here's what I got:
http://www.dpmsinc.com/store/products/?prod=863&cat=1867
I paid $120 including tax at a gun show, so I thought I got a decent deal. I'm new to the AR 15 building thing, but have you heard of problems with this receiver?

I don't have any other parts available to test with. This is my first build, and so I don't yet have a stockpile of spares. Although I do plan to have that one day.
458winmag  [Team Member]
10/27/2011 12:09:50 AM
Originally Posted By eric10mm:
If all the LPK parts and FCG parts came from one supplier, I'd get on the horn with them for WARRANTY replacements.

If they won't solve your problem, shout it from the mountain tops!

ETA: Are you sure your lower is in-spec enough to work? Have you tried installing regular FCG parts and testing them?


Each will blame the other. OP, try here for a mentor.

http://www.ar15.com/forums/f_8/8_Texas.html
RCarter  [Member]
10/27/2011 2:54:25 AM
With the hammer de-cocked , selector installed on fire (shouldn't be able to go to safe de-cocked ). Check to see if you can pull the trigger back a little . You should be able to move it back about 1/16" - 3/32" before it hits the selector , it should kind of feel like the 1st stage .
eric10mm  [Team Member]
10/27/2011 5:22:52 AM

Originally Posted By Auxilio_ab_alto:
Originally Posted By eric10mm:
If all the LPK parts and FCG parts came from one supplier, I'd get on the horn with them for WARRANTY replacements.

If they won't solve your problem, shout it from the mountain tops!

ETA: Are you sure your lower is in-spec enough to work? Have you tried installing regular FCG parts and testing them?


No, I'm not 100% sure about the lower being mil-spec. My original intention was to purchase a mil-spec lower, but I guess I may have messed up. Here's what I got:
http://www.dpmsinc.com/store/products/?prod=863&cat=1867
I paid $120 including tax at a gun show, so I thought I got a decent deal. I'm new to the AR 15 building thing, but have you heard of problems with this receiver?

I don't have any other parts available to test with. This is my first build, and so I don't yet have a stockpile of spares. Although I do plan to have that one day.

Well, technically, no semi-auto receiver is ever going to be "mil-spec", but I know of a great many DPMS receivers that run just fine.

As 458winmag wrote, find a friend local to you who has a known-to-function receiver to which you can compare yours.
Dano523  [Moderator]
10/27/2011 9:44:17 AM
Were to begin?????

Out the gate, there is way too much creep from the trigger at rest to hitting the selector when set on safe. This could be corrected with a set screw up the pistol grip channel to take up that creep, but as it, just way too much,even for a two stage trigger.

Next as stated, the tail of the hammer needs to fit into the selector fire slot, and although it appears to be fine when the parts are dry fitted outside of the rifle, may still have a problem with either the U slot on in the correct position, or even the trigger forward of the back flat striking the selector and limiting the trigger. Yes, all of this can be milled corrected with a Carbine end mill, hence not something that you want to try to hack away at free hand.

But lets back it up, if you do need to smith the selector (read machine), and may be even set the second stage crisp at well, then the FCG is far from a drop in unit, and you need to think long and hard if you should either just replace the FCG with a drop in unit, such as a RRA one, or if you want to go the extra mile by sending the rifle in to have the NM fitted instead.


I could write you a novel on how to fit a NM trigger, but if you are not geared up with the correct tooling, your going to just botch the job. So the call is yours, but would suggest that you look into another NM trigger that is either adjustable so you don't have to smith, or if you want a non adjustable NM trigger, find one that is drop in instead.
Auxilio_ab_alto  [Member]
10/27/2011 10:55:40 AM
Originally Posted By eric10mm:
Well, technically, no semi-auto receiver is ever going to be "mil-spec", but I know of a great many DPMS receivers that run just fine.

As 458winmag wrote, find a friend local to you who has a known-to-function receiver to which you can compare yours.


Yeah, I'm aware it won't be actual mil-spec unless lots of inspectors have been roaming their shop testing things. But just them attempting to follow the specifications as closely as possible should be good enough.
Originally Posted By Dano523:
Were to begin?????

Out the gate, there is way too much creep from the trigger at rest to hitting the selector when set on safe. This could be corrected with a set screw up the pistol grip channel to take up that creep, but as it, just way too much,even for a two stage trigger.

Next as stated, the tail of the hammer needs to fit into the selector fire slot, and although it appears to be fine when the parts are dry fitted outside of the rifle, may still have a problem with either the U slot on in the correct position, or even the trigger forward of the back flat striking the selector and limiting the trigger. Yes, all of this can be milled corrected with a Carbine end mill, hence not something that you want to try to hack away at free hand.

But lets back it up, if you do need to smith the selector (read machine), and may be even set the second stage crisp at well, then the FCG is far from a drop in unit, and you need to think long and hard if you should either just replace the FCG with a drop in unit, such as a RRA one, or if you want to go the extra mile by sending the rifle in to have the NM fitted instead.


I could write you a novel on how to fit a NM trigger, but if you are not geared up with the correct tooling, your going to just botch the job. So the call is yours, but would suggest that you look into another NM trigger that is either adjustable so you don't have to smith, or if you want a non adjustable NM trigger, find one that is drop in instead.


According to RRA, the trigger I have is supposed to be a drop in unit.
I've heard adjustable triggers add to the complexity of the build and I prefer to keep things fairly simple.
Dano523  [Moderator]
10/27/2011 11:18:44 AM
Originally Posted By Auxilio_ab_alto:
Originally Posted By eric10mm:
Well, technically, no semi-auto receiver is ever going to be "mil-spec", but I know of a great many DPMS receivers that run just fine.

As 458winmag wrote, find a friend local to you who has a known-to-function receiver to which you can compare yours.


Yeah, I'm aware it won't be actual mil-spec unless lots of inspectors have been roaming their shop testing things. But just them attempting to follow the specifications as closely as possible should be good enough.
Originally Posted By Dano523:
Were to begin?????

Out the gate, there is way too much creep from the trigger at rest to hitting the selector when set on safe. This could be corrected with a set screw up the pistol grip channel to take up that creep, but as it, just way too much,even for a two stage trigger.

Next as stated, the tail of the hammer needs to fit into the selector fire slot, and although it appears to be fine when the parts are dry fitted outside of the rifle, may still have a problem with either the U slot on in the correct position, or even the trigger forward of the back flat striking the selector and limiting the trigger. Yes, all of this can be milled corrected with a Carbine end mill, hence not something that you want to try to hack away at free hand.

But lets back it up, if you do need to smith the selector (read machine), and may be even set the second stage crisp at well, then the FCG is far from a drop in unit, and you need to think long and hard if you should either just replace the FCG with a drop in unit, such as a RRA one, or if you want to go the extra mile by sending the rifle in to have the NM fitted instead.


I could write you a novel on how to fit a NM trigger, but if you are not geared up with the correct tooling, your going to just botch the job. So the call is yours, but would suggest that you look into another NM trigger that is either adjustable so you don't have to smith, or if you want a non adjustable NM trigger, find one that is drop in instead.


According to RRA, the trigger I have is supposed to be a drop in unit.
I've heard adjustable triggers add to the complexity of the build and I prefer to keep things fairly simple.


Then if the trigger is a RRA, either it, the receiver, or the selector is out of spec. So on that note, talk to RRA about you sending them the built lower receiver so they can figure it out.

Auxilio_ab_alto  [Member]
10/27/2011 9:21:59 PM
Thanks for the help everyone. I decided that rather than invest time and large amounts of money into fixing it, I should try to fit the fire selector myself.

I bought a metal file from Home Depot for $5 (I'm a college student and don't yet have a nice toolset) and grinded down the safety a bit and made the notch deeper. Took a while, because I checked it every now and then to see if I had done enough and didn't want to overdo it. Got it so that it goes through the first stage, then hits a spot where it's a bit tougher to pull through. But if you pull it even slightly from there, the hammer releases. Exactly how it should be in a two stage trigger I believe. Not the smoothest grind job (I probably need a dremel) but it functions. I'm a little worried about the metal finish on the selector and how well it will stand up. I put a bit of WD40 on it to try and help. But I believe it's going to work now.

Just gotta wait for my upper to come in so I can take it to the range!
RCarter  [Member]
10/27/2011 11:09:53 PM
WD-40 will gum up after a while . Get some Birchwood Casey perma blue , wal-mart has it if you can't find a gun shop near you . Also , get some good gun oil .
Barman84  [Member]
10/28/2011 9:21:45 AM
After reading all this you finally got it to work. But a small part of me makes wonder if your pistol grip screw is just a bit to long as well. Poking through the bottom of the lower reciever. By notching the safety you have somewhat fixed the problem but seriously back the screw up just a few turns and see if that takes away any of the extra effor put into pulling the trigger.
Dano523  [Moderator]
10/28/2011 9:39:50 AM
Originally Posted By Barman84:
After reading all this you finally got it to work. But a small part of me makes wonder if your pistol grip screw is just a bit to long as well. Poking through the bottom of the lower reciever. By notching the safety you have somewhat fixed the problem but seriously back the screw up just a few turns and see if that takes away any of the extra effor put into pulling the trigger.


Just the opposite,hence if the pistol grip screw was protruding,and you have watched his video, then it would have taken up some of the unneeded creep from the trigger at rest, to against the selector at safe.

Where you see protruding grip screw problems is that the selector can not be set to safe with the hammer cocked.

Auxilio_ab_alto  [Member]
10/28/2011 10:25:35 AM
Originally Posted By Barman84:
After reading all this you finally got it to work. But a small part of me makes wonder if your pistol grip screw is just a bit to long as well. Poking through the bottom of the lower reciever. By notching the safety you have somewhat fixed the problem but seriously back the screw up just a few turns and see if that takes away any of the extra effor put into pulling the trigger.


The problem was there whether the pistol grip was installed or not, so I don't think that affected it.

I think there are 3 possible root causes for my problem. The back of the trigger was either out of spec, the safety was out of spec, or my lower was out of spec. I'm betting it's the lower, since a couple of other parts from my kit (mag catch, trigger guard roll pin) just wouldn't fit. It seems like just grinding down the safety so that it fits would probably solve the problem for anyone else in my situation. I've ordered replacement parts from DPMS, and they should solve the issue with the other stuff not fitting. I'm hoping they'll arrive today...
Schleprock  [Member]
10/28/2011 10:56:09 AM
The first thing I would have done personally is to make sure the rear of the trigger "shoe" was not hitting the rear of the trigger slot in the bottom of the receiver, blocking it's full travel.
Hopefully you didn't remove too much material from the selector surface. That would result in an excess amount of trigger over-travel, and we don't want that right?

Just curious..... with the safety ON, can you feel ANY movement when you pull on the trigger?
eric10mm  [Team Member]
10/28/2011 12:41:41 PM

Originally Posted By Auxilio_ab_alto:

I think there are 3 possible root causes for my problem. The back of the trigger was either out of spec, the safety was out of spec, or my lower was out of spec. I'm betting it's the lower, since a couple of other parts from my kit (mag catch, trigger guard roll pin) just wouldn't fit. It seems like just grinding down the safety so that it fits would probably solve the problem for anyone else in my situation. I've ordered replacement parts from DPMS, and they should solve the issue with the other stuff not fitting. I'm hoping they'll arrive today...

If you are just talking about the roll pins being hard to install, most of the more affordable LPKs do not have friendly tapers on their roll pins. Beyond that, as long as it is the proper length and diameter, a roll pin pretty much either works or it does not. I usually either put my roll pins into a cordless drill and install a nice taper on one end using a good file, or simply squeeze it with some good pliers.

Out of curiosity, I would have first tried normal FCG parts in the lower to see if they offered any problems.

The selector is not considered a wear item and should last indefinitely even with your mods to it. Just cover the "work" with some paint, cold blue & oil, or just oil.
Jered33  [Member]
10/28/2011 4:24:51 PM
I had that same problem with a Dpms lower and rra 2stage . I ended up filing couple thousands off selector to fix it.
myco4you  [Member]
10/28/2011 5:46:24 PM
A lot of people on this forum are in Texas.I'm sure you can find someone local that knows what they are doing,and have them help you out.

No offense to the OP,but you need some hands-on help.You are grinding on your FCG,and now think the lower is out of spec?
Auxilio_ab_alto  [Member]
10/28/2011 8:48:04 PM
Originally Posted By eric10mm:
If you are just talking about the roll pins being hard to install, most of the more affordable LPKs do not have friendly tapers on their roll pins. Beyond that, as long as it is the proper length and diameter, a roll pin pretty much either works or it does not. I usually either put my roll pins into a cordless drill and install a nice taper on one end using a good file, or simply squeeze it with some good pliers.

Out of curiosity, I would have first tried normal FCG parts in the lower to see if they offered any problems.

The selector is not considered a wear item and should last indefinitely even with your mods to it. Just cover the "work" with some paint, cold blue & oil, or just oil.

I don't have normal FCG parts. This is my first build.

I got my new roll pin, and can't get it into the trigger guard. I even broke some needle nose pliers trying to squeeze the roll pin to have a smaller diameter.

My new mag release doesn't fit either, too fat to fit in the slot. So I'm fairly positive the lower is just out of spec. So I'm grinding down the mag release. It's very slow going with a metal file.

Originally Posted By myco4you:
A lot of people on this forum are in Texas.I'm sure you can find someone local that knows what they are doing,and have them help you out.

No offense to the OP,but you need some hands-on help.You are grinding on your FCG,and now think the lower is out of spec?

Yeah. Did I do something wrong? I figure it makes sense to modify the cheapest parts to make them fit the more expensive parts. You can always replace the cheap parts if you ruin them. Although it seems like no amount of replacement parts would make it work if the lower is this far out of spec.

Originally Posted By Schleprock:
The first thing I would have done personally is to make sure the rear of the trigger "shoe" was not hitting the rear of the trigger slot in the bottom of the receiver, blocking it's full travel.
Hopefully you didn't remove too much material from the selector surface. That would result in an excess amount of trigger over-travel, and we don't want that right?

Just curious..... with the safety ON, can you feel ANY movement when you pull on the trigger?

It wasn't hitting that. It was hitting the depression in the selector like I said earlier in this thread and showed in the video. I removed enough material to make the trigger work, and now the trigger work great. Once the trigger is pulled through the second stage, the hammer immediately releases and the trigger doesn't go any further back.
Auxilio_ab_alto  [Member]
10/28/2011 8:48:45 PM
Woops double post.
Schleprock  [Member]
10/28/2011 9:28:36 PM

Originally Posted By Auxilio_ab_alto:

It wasn't hitting that. It was hitting the depression in the selector like I said earlier in this thread and showed in the video.

Ahhhh... indeed you did. I guess I glazed over the first part where you had the selector removed from the receiver.
My apologies for missing that the first time.

Keep em in the x-ring!

Auxilio_ab_alto  [Member]
11/13/2011 4:12:15 PM
In case anyone runs into this problem, I've managed to solve it.

The lower was almost definitely slightly out of spec. Like I said above, grinding the safety/selector down a bit fixed the trigger group.

My mag catch/release wouldn't fit in the slot either (I tried two different ones). And it turns out that the mag release is a hell of a lot tougher than the fire selector, and was nearly impossible to manually grind down with a metal file. The lower is made of material that isn't as tough, and it's kind of hard to work a file in there. But I managed to grind down the slot enough to fit the mag release in. My lower is now fully functional, and I'm awaiting the completed upper to come in from Fulton Armory so I can check it at the range.

Not really sure why my lower came so out of spec. I had heard good things about DPMS, and their customer support seemed friendly enough. Maybe I just got a really old one or it somehow slipped through quality control.