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I have pieced together a new 6.5 G AR15 Pistol the last 2 weeks. I added a drop in trigger and found it would not reset in my living room. I checked online and saw a couple others had similar issues. I worked the trigger manually about 100 times and it still would not reset by itself. I had to push it forward.
I cleaned trigger up and oiled it lightly with Lucas Extreeme, it still would not reset but felt 100% smoother. I then found the trigger was binding on the sides of the trigger hole. I pulled trigger group out again and I carefully sanded/polished the inside sides of the trigger hole with 1200 grit sand paper on a popsicle stick removing a little of the coating on the sides of the trigger hole. I put it back together and it seems to be working fine..
I have been unable to live fire this new build as I don't have access to my shooting range till April 26th and the Public range is closed due to the C19. This new trigger now feels lighter and has much less take up. Lesson learned>>>always clean new trigger groups even if they "look" all new and shiny and sometimes parts rub more than they should.. Another lesson learned.
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What trigger?
What lower?
What did you grind out of the trigger?
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Who makes that drop in trigger?
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no grinding..I only lightly polished the inside of the lower trigger hole with 1200 grit wet/dry sandpaper wrapped on a Popsicle stick removing a small amount of the finish not exposing any aluminum. The trigger seemed to be rubbing a little on the left side but I polished both sides, 1200 grit is pretty fine and does not remove much before clogging up. The trigger group looked pretty clean right out of the box but there was a little bit of something in there that i cleaned out before applying the Lucas oil. 2.5# CMC trigger, Core15 lower. I have 2 other Core15 lowers one with a RA-434 trigger and one with a RA-140 trigger both work nicely. Since the cleaning, oiling and polishing the CMC trigger feels pretty darn good I'll know more when I live fire it.
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I own several CMC 1 stage 2,5# triggers. I never had to do anything to them. If I had any problems Id send them back,Im sure Chip would make them right.
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No need to send it back. After the cleaning the gritty grease out and oiling of the new clean looking trigger it was smoother but would not reset.. then the polishing of the receiver trigger hole..now the trigger is good to go. At first there was a lot of travel and it would not reset unless I manually pushed it forward. I looked at reviews on line and saw others had the same reset issue. Looking closer with a light I could see that it was lightly rubbing on the left side and right side had a little space between trigger and lower trigger hole.. I polished that area with 1200 grit sand paper removing a small amount of the finish..now it has near zero travel before it breaks and feels lighter. It was a learning lesson for me as I had not had trigger issues with the other two lowers I have. If I was to put the trigger into a another lower and it did the same thing then I would think it's a centering issue with the trigger group..at this time I am good to go.
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RobertFL,
just curious. when you discovered the trigger and lower had too tight a fit, why did you decide to widen the lower rather than make the trigger bosses a little narrower? i would think the trigger part cheaper and more easily replaced than a lower. either way will work of course.
-tdbru
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This is only my 3rd AR style rifle/pistol. I have very little experience working on them since I have never had a problem. Working on triggers is way outside of my skill set right now. I have heard stories of trigger work gone bad.. Polishing the area with the 1200 grit paper was my best choice with my current skill set.
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I was able to shoot the new rifle this past weekend. The CMC flat 2.5# trigger worked very well. I have some bolt action rifles with stock triggers that I thought were good and 2 other AR style rifles with RA 3.5# triggers that I really like. The 2.5# CMC trigger really surprised me, you better be ready to shoot when you touch the trigger! It's not scary but it don't take much effort..
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Sounds like a tolerance stack issue between the Core15 lower and the CMC trigger.
As long as a hard anodize per the Mil-Std is still in place inside the trigger holes, it should last a lifetime of semi-auto use.
NRA Basic, Pistol, Rifle, Shotgun, RSO
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