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Posted: 6/30/2005 4:22:02 PM EDT
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Have a Bushmaster upper (broken in), installed a new DPMS bolt. It chambers the round fine but then locks up TIGHT. I totally removed my right middle finger nail pulling the CH to the rear, but got it to come back. I disassemled, cleaned and recleaned and it does the same every time. Even installed the bolt into another upper and again, it locked up tight. Any suggestions? Thanks for any help. I figured part of it out. I swapped buffers with a broken in buffer from another BCG and it works fine. Anyone know how to lighten up or smooth out a new buffer? |
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Bolt and carrier or just the Bolt, And you have checked the headspace with the new Bolt? As for the buffer problem, check the bumper end roll pin. It may be sticking out and catching a spring wind. If needed, use a file and flush the ends. Also, check the end of coil of the buffer spring (both ends). The end of coil may have a end high point too and need to be taken (read scraping down the receiver extension and causing the bind). |
Roll pin looks fine, buffer spring OK. It's definitely a problem with the bolt assy, cause when I swap it out with a broken in bolt assy, the whole BCG does fine. Just cant tell what the bolt's problem is. |
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When I use the new bolt it seats the round and sticks making pulling back the CH rediculously difficult. When I swap it with my old one it functions flawlessly. I am using an El Cheapo buffer/ spring, but that does'nt seem to effect function with the broken in buffer. *Also, when I cycle the problem bolt, it locks fine unless I am locking and loading a round. |
| May be onto something. I took some fine sandpaper and softened the edges of the bolt faces ridges. It still locks up a bit after the round is seated but is getting easier to pull back the CH and eject. I noted that the older DPMS bolt has teeth that are a bit more narrow. I'll test fire tomorrow and let ya'll know how she does. Thanks for the tips. |
well, I was going to recommend that you go shoot it, taking sand paper to surface hardened parts isn't the best approach, esp on a part 6" from your face that restrains 50,000 psi.  I don't think your problem is related to the buffer but I'm damned if I can think of the relationship unless one buffer just slaps the carrier harder. When I asked about buffers I was asking about the make (Al with sliding weights, plastic with birdshot, etc.) and the model (rifle or carbine) Most weird problems like this are solved on the details. |
| After reading this post, its my understanding that the bolt "locks-up" tightly on a closed chamber and it nearly impossible to cycle. Perhaps the carrier key's internal dimensions aren't to spec'. The mating of the carrier key and the gas tube may be of such tight tolerances that the problem has happened. Just my .02 |
Nope, he has a Brand new bolt that still has a bit of milling burs on it. The binding is the back of the bolt lugs to the face of the Simply stated, is its just a case of the rifle needing to be broken in threw live fire. |
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