1stTimeBldr Posted December 19, 2020 Report Share Posted December 19, 2020 I am in the final stages of building a JMT 80% AR-10 polymer lower. Milling went ok, and basic parts installation (pivot pin, mag release, bolt stop, trigger) all went ok. When I install the safety selector by itself, everything works normally - drop-in trigger releases on Fire, does not release on Safe. When I install the detents / springs and pistol grip, the trigger no longer releases on Fire. With the grip installed, I can move the safety selector between Safe and Fire easily and I feel the detent engage in both positions. I have tried the following troubleshooting steps: Install safety selector only: Trigger functions normally Install safety selector, and grip screw only (no grip or detents ): Trigger functions normally. Install safety selector, grip, and screw – with the screw backed out several turns (there is about a millimeter of space between the grip edge and the border of the grip mount on the lower. I did this because several posts mentioned that the screw might be overly tight.): Trigger does not function Install safety selector, grip, and screw fully tightened: Trigger does not function Take it all apart – Trigger functions normally I am at a loss – I do not know how the grip could be affecting the trigger. Any ideas? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 19, 2020 Report Share Posted December 19, 2020 Pics will help, here. Sounds like the grip screw is too long, goes into the lower, and contacts the bottom of the trigger. Can't tell without pics, though. Welcome aboard - go rip up the intro section, and tell us about yourself. It's right here: https://forum.308ar.com/forum/22-introductions/ Quote Link to comment Share on other sites More sharing options...
sketch Posted December 19, 2020 Report Share Posted December 19, 2020 2 hours ago, 98Z5V said: Pics will help, here. Sounds like the grip screw is too long, goes into the lower, and contacts the bottom of the trigger. Can't tell without pics, though. Welcome aboard - go rip up the intro section, and tell us about yourself. It's right here: https://forum.308ar.com/forum/22-introductions/ my first thoughts also or 80% saftey holes are off by a thou or two. add a washer in the mix of the grip screw for starters. Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 19, 2020 Author Report Share Posted December 19, 2020 Photo below. The pistol grip is attached. Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 19, 2020 Author Report Share Posted December 19, 2020 I believe I have found the cause. When I install the safety selector (before the detents, spring, and grip) and push it all the way through so that the selector lever is flush with the surface of the lower, if functions normally. During grip installation, I can feel the detent engage and the selector pushes out to about a millimeter above the surface of the lower. The selector crossbar has a raised lip where it goes into the hole on the other side of the lower - and when that pokes out into the well, that's enough to prevent "Fire" from functioning. So, I know the cause but not the fix. Is this just a bad selector? Quote Link to comment Share on other sites More sharing options...
shooterrex Posted December 19, 2020 Report Share Posted December 19, 2020 Could be the safety or the detent hole is in the wrong location. You can probably just remove a bit of material off the safety so the trigger will move. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 19, 2020 Report Share Posted December 19, 2020 5 hours ago, 1stTimeBldr said: The selector crossbar has a raised lip where it goes into the hole on the other side of the lower Sounds like a Battle Arms 45* selector. Get a pic in here of what you're talking about, on that selector... Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 19, 2020 Author Report Share Posted December 19, 2020 The selector is a no-name that came with a lower parts kit. Interestingly, the replacement I ordered is a Battle Arms. They all have that same lip or rim to fit the hole drilled in the lower. The problem here seems to be that the detent is pushing it into the well a bit. I should get the new selector in a few days and hopefully that fixes it. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 21, 2020 Report Share Posted December 21, 2020 On 12/19/2020 at 1:59 PM, 98Z5V said: Get a pic in here of what you're talking about, on that selector... On 12/19/2020 at 2:51 PM, 1stTimeBldr said: The selector is a no-name that came with a lower parts kit. Interestingly, the replacement I ordered is a Battle Arms. They all have that same lip or rim to fit the hole drilled in the lower. The problem here seems to be that the detent is pushing it into the well a bit. I should get the new selector in a few days and hopefully that fixes it. Again, Get a pic in here of what you're talking about, on that selector... Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 21, 2020 Report Share Posted December 21, 2020 I'm not sure if I'm tracking here, but what I think is happening is that you've installed the grip and it's grip safety, THEN you're trying to install the Safety... and it won't go,because the detent is pushing it up out of the way?... Quote Link to comment Share on other sites More sharing options...
shooterrex Posted December 21, 2020 Report Share Posted December 21, 2020 I think the problem is his safety detent hole is just a bit to much to the center of the lower and is pushing the safety back out of the lower just enough. So the safety doesn't clear the trigger. That's how I understand bthe post. Pics sure would help. Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 21, 2020 Author Report Share Posted December 21, 2020 20 hours ago, shooterrex said: I think the problem is his safety detent hole is just a bit to much to the center of the lower and is pushing the safety back out of the lower just enough. So the safety doesn't clear the trigger. That's how I understand bthe post. Pics sure would help. This is probably the issue. The hole was pre drilled, nothing I can do about that. I am hoping that the on-order safety is just a little narrower, enabling the trigger to clear the safety. If not I think I am out of luck. Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 21, 2020 Author Report Share Posted December 21, 2020 21 hours ago, 98Z5V said: I'm not sure if I'm tracking here, but what I think is happening is that you've installed the grip and it's grip safety, THEN you're trying to install the Safety... and it won't go,because the detent is pushing it up out of the way?... No; the safety gets installed at the same time as the grip and detent. When the detent engages the safety, it pushes the safety about a millimeter inwards, and that blocks the trigger from acting. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 22, 2020 Report Share Posted December 22, 2020 (edited) 6 hours ago, 1stTimeBldr said: No; the safety gets installed at the same time as the grip and detent. When the detent engages the safety, it pushes the safety about a millimeter inwards, and that blocks the trigger from acting. That's a bad safety, then - not machined right, just like you thought. The actual safety lever shouldn't shift left-right, when you engage it. If that's happening, you could cut that thing, and make it work. Edited December 22, 2020 by 98Z5V Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 30, 2020 Author Report Share Posted December 30, 2020 My replacement safety selector arrived, and while the overall dimensions were identical, I saw that the well for the detent was cut much narrower. I installed the selector, detent, pistol grip, etc. - and as the safety detent engaged I felt the selector pop out a bit towards the lever side. Exact same problem. The clearance between that and the trigger bar (not sure of the terminology) is so small that this prevents the trigger from firing. So, it is either a defect in placement of the detent hole (factory drilled) or in my milling of the fire control group pocket. Although it seems unlikely, I am tending towards the detent hole being misplaced, because on every other AR, the selector switch is flush with the lower - not pushed out about a millimeter (see attached picture). Either way, I think this lower is a dead issue and I need to start over. Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 30, 2020 Author Report Share Posted December 30, 2020 11 minutes ago, Swiftab said: They make a push-bottom Safety if you don’t want to start over: A $35 fix is a much cheaper alternative than a new lower. I think I will give that a try. Thanks! Quote Link to comment Share on other sites More sharing options...
Lane Posted December 30, 2020 Report Share Posted December 30, 2020 You could alternatively fix it for free if you have a file. Widen the safety selectors flat section on the side that's engaging the trigger's tail. Should take about 5 minutes at most. Pardon the random ambidextrous safety selector image; but either left or right where the purple arrows point. Be careful not to dig into the flat spot in the middle. Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted December 30, 2020 Author Report Share Posted December 30, 2020 While it may be possible to do that without compromising safety, I do not plan to make any mods to parts. Easier and safer to replace the lower. Quote Link to comment Share on other sites More sharing options...
392heminut Posted December 30, 2020 Report Share Posted December 30, 2020 7 hours ago, Lane said: You could alternatively fix it for free if you have a file. Widen the safety selectors flat section on the side that's engaging the trigger's tail. Should take about 5 minutes at most. Pardon the random ambidextrous safety selector image; but either left or right where the purple arrows point. Be careful not to dig into the flat spot in the middle. That right there is the legitimate fix! As long as you don't cut into the flat itself it's a perfectly safe fix, probably take a bout 2 minutes. Go to the hardware store and buy a 'fine' mill bastard file, grind the teeth off of one edge to make what's called a 'safe edge' and you won't even have to worry about cutting into the flat! Both of those safeties could be made to work in less time than it takes to go online and order another receiver but hey, it's your money! Quote Link to comment Share on other sites More sharing options...
98Z5V Posted December 31, 2020 Report Share Posted December 31, 2020 If it was mine, I would have already cut that safety, on the first one. See my post from Dec 21st. Quote Link to comment Share on other sites More sharing options...
1stTimeBldr Posted January 13, 2021 Author Report Share Posted January 13, 2021 The Elftmann Tactical Ambi AR Push Button Safety is installed and functioning properly. It provides enough clearance for the trigger pull. Thanks to the commenters. Quote Link to comment Share on other sites More sharing options...
Armed Eye Doc Posted January 14, 2021 Report Share Posted January 14, 2021 Glad to hear that solution worked well for you. Quote Link to comment Share on other sites More sharing options...
DNP Posted January 14, 2021 Report Share Posted January 14, 2021 That’s great news. Get out and shoot! Quote Link to comment Share on other sites More sharing options...
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