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New M4-22 Owner with trigger issues

576 Views 4 Replies 2 Participants Last post by  richlennehan
Hello everyone, this is my first post here and unfortunately I am opening up with an issue.

I purchased my M4 in November from Resilient Arms (awesome service and shipping!). I shot my first 500 rounds of CCI and another 800 rounds of Remington through it with no issues. I purchased a LaRue MBT-2S for it and... that is when my issues started.

After installing the LaRue the M4 started short stroking. The bolt was pretty consistently not resetting the trigger and leaving rounds down in the magazine. Additionally the rifle felt strange when I manually charged it. There were three distinct feelings when pulling the charging handle back. The bolt would actually catch after the third feel and not slam forward. Inside the upper also looks to have some aluminum deformation (the second image) where the bolt slides beside the ejection port now too .

I contacted the guys at Tippmann (who are also awesome I should add). They recommended I remove the LaRue hammer spring and use the Tippmann. The other thing we discussed was removing 10 thou from the underside of the bolt. I swapped springs and put the bolt on the surface grinder removing 6 thou.

I will test the rifle out this weekend. That being said, the bolt still has those three feelings and slightly catches after the third feeling. Has anyone else experienced issues like this with the LaRue trigger?
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Well, I have only been able to put 150 rounds through it since changing the hammer spring. There hasn't been a single failure, nothing. The ammo is Federal 40 grain bulk stuff, 800 rounds for $34. This is the same ammo that was not feeding and the bolt not seating prior to swapping the hammer spring. I will try and put another 200 rounds through it and see if anything changes.
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I am now through 800 rounds of the Federal bulk stuff. Over 700 rounds of it has ran without a single hiccup after replacing the hammer spring!
Nice to know they were able to diagnose and help you fix the issue. I’ve only had one interaction with Tippmann customer service and they were great to deal with.
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