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Posted: 10/10/2008 6:02:44 AM EDT
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Okay, so here goes. I have a Tactical Innovations TAC-15 lower receiver with a Rock River LPK and 2-stage trigger. I've assembled it with several uppers, and the bolt catch will not completely engage the bolt on any of them. It almost locks the bolt, but as soon as I release thumb pressure off the lower half of the catch, the bolt goes forward. It appears that it's not canting up high enough, whether with an empty magazine inserted or by manually locking the catch. Also, an empty magazine (I tried several) doesn't seem to have enough force for the follower to push the bolt catch up all the way. The same magazines did this with no problems in other lowers. It was probably a bad idea, but I thought I could fix the problem by removing some material around the hole where the bolt catch spring and buffer sit. My thinking was that this would provide more clearance for the catch before it bottomed out against this surface, allowing it to cant up farther. While this didn't make the problem any worse, it didn't fix it either. So here I sit with this awesome new LaRue upper that I can't use. I'm sure the gun would shoot, but I don't want to risk it. Anyone seen this problem before, or have a suggestion to fix it? I have a feeling I'm screwed on the warranty, since I altered the lower. Any help would be greatly appreciated. ETA: After the initial post, I also tried swapping out the entire bolt catch assembly (catch, spring, buffer, and roll pin) with one from a rifle that I knew to function fine. No luck there, either. |
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There's crap in the hole that the bolt catch spring goes into, or the spring is too strong. Cheapest fix first is to clip off a bit of the spring and see if this allows the catch to be pushed up by the mag. I have no idea what the depth of the hole is supposed to be but you could check it. Also, make sure you have the correct spring and plunger. Gringop |
| I had a similar problem with a Cav/Eagle Arms build and simply trimming the bolt catch spring didn't do it for me. I had to shorten the tail on the bolt catch plunger and shorten the spring but now the bolt catch engages readily. You might want to order a few spares of the parts involved so you won't be dead in the water if something doesn't work out for you. |
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What stock do you have on the lower? I had a similar problem with my A2 stocked lower because some bozo had "lost" the stock screw and used a non-standard screw as a replacement. It was just long enough that the buffer couldn't go back far enough for the bolt catch to engage. I finally determined that the reason the bolt catch wasn't functioning properly by loosening the stock screw a little which allowed the buffer to be pushed back enough to allow the bolt catch do engage. I picked up the correct screw (the one with the hole through it) at a fun show and have been happy ever since. YMMV buy one thing to consider before you go messing up your lower. |
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Thanks for the input guys. I've already tried using the bolt catch without the buffer or spring inserted; still won't catch. As for the stock, I have a Magpul UBR. not sure if that should make a difference or not. I'm about to pull it and see what happens... more to come... ETA: Nope, no dice there, either... I removed the stock bolt from the buffer tube, still having the same problem... Thanks for trying, though... |
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Okay, so i'm an idiot. With all the steps I took troubleshooting this thing, including removing the stock screw to make sure it wasn't too long and blocking the buffer, I never thought to shine a light down in the buffer tube. While I love my UBR, I think the boys at Magpul could have found a better place to stash the baggy with 4 allen screws and a washer (now bent) inside. The bolt wasn't going back all the way because this had been there ever since I assembled the lower. Good thing I never shot it. So fair warning, check your buffer tubes on new builds! beaker |
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