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Posted: 10/31/2008 7:12:07 AM EDT
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Mellow greetings fellow ARFers.
I have a problem with my BAR-10. I've read the FAQ, the List Rules, the Sample Post and the Glossary and couldn't find this exact problem. My BAR-10 is a 16 inch A2, Bushmaster, chambered in 7.62 NATO, using FAL magazines, and it's failing to feed reliably with FAL Metric surplus 20 round mags firing SA 7.62 surplus, Winchester WB 168 gr, and Federal American Eagle 155 grain ammo. Out of 25 purchased magazines, only 6 fed reliably enough to shoot 5 rounds, five times, without jamming. The thrid to last, second to last, and last magazine rounds are most likely to jam. The rifle was sent back to Bushmaster when I purchased it FTF at a show. It would seriously gouge the nose of the Winchester soft points, and American Eagle ball ammo, probably on the magazine's lips from the shape of the gouge. They replaced the bolt, swapped out my magazines, and swapped the skeleton stock for a standard A2. They said it test fired reliably and shipped it back. It began jamming with the first magazine afterwards. The bolt comes back far enough, or close to far enough to clear the end of the round, then slides OVER the first round atop the magazine, as the lug scratches begin at the rearmost edge of the casing, below the rim. It drags against the round hard enough to strip it from the magazine, but the round then has nowhere to go, and ends up sideways, primer out the ejection port. Once in 100 attempts, it will also pick up the first round ok, but just seems to run out of steam before the rifle goes into battery. I though maybe 30 year old mag springs weren't getting the round up fast enough for the bolt to catch them on its way forward, so I replaced one magazine spring with the Wolfe 105 percent FAL springs, and this seemed to fix the problem (that day, anyway), so I replaced all the magazine springs, but the new springs are not doing any better than the old. Every once in a while on a slow rearward manual movement of the bolt, the bolt lugs will catch the cartrige rim, tip the slug up out of the magazine, then jam on the way forward, but this doesn't seem to be the primary mode of failure. This rifle is very accurate for its model/class. My High Master buddy put five in a 1.7 inch circle at 200 yards, with a sling, but since the barrel isn't free floated yet, I may be able to get it tighter still. It just won't run reliably. I've read the vast quantity of internet literature on these rifles, found most of it to be false (missing lug, bolt cracking problems misstated), but I've also read that many of these rifles run reliably. RRA bought the design back from Bushmaster, and the new LAR-8s all seem to run reliably, so I know it's at least possible. Please help me, as I really really love this rifle's accuracy, and I've been told you guys are the best. Thanks in advance. A rookie out of his league. |
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Hey,
I have two BAR-10s two Noveske 308s and an AR-10. Your mags are probably not the problem. Sounds like your timing is off, someone may have put the wrong buffer in your buffer tube, the BAR has a special rifle buffer only made for it. I bet someone replaced it. The way I got my BARs running reliably was by replacing the stock rifle buffer tube with Vltors AR-10 carbine buffer tube extension and using slashs buffer and an uncut ar-10 carbine or rifle buffer spring. The Vltor is also milspec diameter just so you know. I bet you could use an H3 buffer and get the same results.Its what the AR-10 carbine uses. Also you will want to take the bolt carrier out and check the carrier key tightness and stake it better. Also clean out the extractor in the bolt it might have some case shavings gumming it up. That should get you up to speed. |
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I've been wondering about the buffer, for two reasons.
One, Bushmaster replaced the stock, at my request, skeleton to A2 style. Two, some, not many but some, of the jams involve the bufer just not having enouh steam to close and lock the bolt. No apparant misalignment, just too much friction. The downside of a buffer centered resolution process is that the two main modes of failure seem to indicate opposite problems with the buffer. A weak, slow spring would be expected to drag too much and fail to fully chamber an occasional round. But that same slow weak spring would be expected to compress further in the buffer tube, and allow more time for the next round in the magazine to come up, allowing the bolt to catch it squarely and chamber it, instead of scraping along the top side. Main failure mode indicates too strong a buffer spring. Second failure mode indicates not enough buffer spring strength. I don't mind packing it up and sending it back to Bushmaster, or springing for replacement parts, but I'd like to see theory match actual practice, where I have some real knowlege of what's wrong confirmed by observation, before just dumping money into it and hoping something works. |
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