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Posted: 9/6/2002 6:57:42 AM EDT
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I have a bushmaster lower that I bought used. The bolt on serval of my uppers fails to remain in the open position when the magazine is empty. I have inspected the lower and noticed that there is a lot of "forward to back" play in the machanism that holds the bolt open, almost as if something (like repeated dry fire) has enlarged the distance between the two ears on the left side of the lower where the pin retaining this mechanism is housed. My question... has anyone else encountered this issue and what was the solution employed. I was thinging about machining a spacer to fill the gap, or enlarging the pin and retaining holds on the lower. I haven't seen this type of problem before, so I figured I'd ask before making mods to a working lower... |
| He hold-open latch is actually activated when the rear section of the Magazine follower presses up on it. I would say that your hold-open latch spring is stronger than your mag spring. I have a couple of cheapo mags that do this. Either you have a worn out spring in your mag, a cheapo mag like one of my plastic jobs, or the wrong spring/length spring in the hold-open. Check this by pulling the bolt back and using your finger, a pencil or whatever to push on the section of the hold open where the mag follower does. If you're not sure where it touches it just open it up and pop in a mag. Where the hold-open touches the follower is where you should push when you pull the bolt back. |
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Another thing to look at, while you're on it, is the wear on the roll pin that your bolt stop fulcrums on....I've found it to be of moderate steel, and can CONTRIBUTE to the problem you are experiencing. If the "ears" of the receiver don't allow play, there is less room for the roll pin to wear. If there is excessive space on the "ears", it could put additional stress on that roll pin, causing it to wear abnormally. When you put the shims in, I'd be somewhat interested in knowing what condition that pin is in. Panz 
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| I have an Essential Arms lower, and have the same problem. I took the top half off, and examined the bolt catch on the lower half, and it looks nice and tight. I then took several magazines, and loaded it into the lower receiver, and I could see the edge of the bolt catch hold the top of the magazine follower, "every" time! Then I would put one round in each magazine, and load it into the lower again. Then I would push the case out by hand, like how a round would be pushed by the bolt, and I could see the magazine followers move forward, just in front of the bolt catch lip, and not lock on to the top of the follower? This happened to almost every mag! You think the lip on the bolt catch might be too short? Or could it be too much play in the hole of my lower receiver, where the mag goes in? The bolt catch seems new? I measured from the front of the lip to the rear, and it measures .445"? Is this about its dimensions? Thanks for any ideas? Dennis |
| I had this same problem on one of my lowers a while back and I contacted Kurts Kustoms and had him weld an extension onto the tip to extend the length of the bolt hold magazine catch just short of touching the back of the bullets in the magazine.Worked like a charm. You guys may want to contact him and have him do the same for you. HTH |
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At the gunshow yesterday I bought a new bolt catch,spring,roll pin,& detent. The fit of the roll pin in the catch I believe was the problem. Causing the sideplay,The original catches hole had worn and the pin was to sloppy in it. The new one has some play nothing like the other one had it is smoother and doesn,t rock back and forth.Also thanks to J&T Distributing for setting me up with the parts for $5 .I looked at 3-4 different ones from other suppliers and they were all different ,the fit of the roll pin that is and some were relieved at the roll pin slot others not? the one I bought had the best fit and was smooth on the sides. All caused by non mil-spec parts.Also don't forget to lube the spring,detent,catch,&roll pin it'll smooth it up I used Breakfree CLP.Will report back after range test I also bought some Wolff mag springs 3 for $9 and green followers$1 ea. And also bought a USGI Center industries new in bag . heavy.gifBeretta92 Well after extensive testing at the range lastnight .IT'S HEALED.Bolt locks open everytime I tried it shot 1 shot from ea mag 6times + shot about 250 rounds its great . heavy.gif |
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