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Posted: 1/7/2014 8:43:23 PM EDT
| This should be suitable for this thread. Well guys it happened today..finally. Wondered how much longer my bolt would last. Broken bolt on BCM Midi-upper (BFH). The upper has around 10,000 rounds or so through it so I guess the bolt couldnt handle any more drills/courses. So I have a brand new bcm bolt that I checked head space with just now and it all checked out. So should I drop this new bolt in and keep banging away or should I get a new upper and start over? If I drop this new bolt in how much more life do you guys think I can get out of this upper? I dont expect much accuracy at all although it still is, all's I want this upper for is running drills so a little bit of rapid fire happens when I am shooting. thanks all. |
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Quoted:
I thought more would be interested in this. I was maybe just a little surprised that the bolt already broke. A "standard" bolt is only good for about 6k...after that it's on borrowed time. You might (no surprise) get about twice that out of it if you ran it to failure. New bolt and your upper (barrel) should be good for another 10k or so, ammunition dependent. |
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Quoted:
A "standard" bolt is only good for about 6k...after that it's on borrowed time. You might (no surprise) get about twice that out of it if you ran it to failure. New bolt and your upper (barrel) should be good for another 10k or so, ammunition dependent. Quoted:
Quoted:
I thought more would be interested in this. I was maybe just a little surprised that the bolt already broke. A "standard" bolt is only good for about 6k...after that it's on borrowed time. You might (no surprise) get about twice that out of it if you ran it to failure. New bolt and your upper (barrel) should be good for another 10k or so, ammunition dependent. Meh. Many bolts go tens of thousands of rounds. Friend of mine got something like 50K through his. Several things influence bolt-life: -Full-auto fire/very rapid semi. -Gas system and properly sized gas-port. -Lubrication. 6K rounds and dead is for a bolt subjected to very harsh use on MK18's and H-buffer M4's. Maybe even cans were involved in that test, I don't know. We are not talking VTAC 2-2-2 drills, we are talking ammo grows on trees Uncle Sam is paying use. Those round-counts came about as part of another project...a round-counting device on-weapon that would have made the company pushing it millions, had it "sold". It is my... opinion...that everything in their power was done to sell that system...and the shorter a bolt lived...the better for them. Look at Filthy 14 again. It broke a bolt at something like 14-16K rounds, I believe, and has been on the same one ever since as far as I know, and has crested 40K at this point. Anyway, yeah, bolts are cheap so I have a spare, but that's about as far as I take things. That 6K round-count you listed isn't exactly optimal conditions, and it was a co-product of a study designed to sell equipment on the premise that bolts break easily and unexpectedly...hmmm More data: http://www.dtic.mil/ndia/2006smallarms/taylor.pdf |
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Quoted:
A "standard" bolt is only good for about 6k...after that it's on borrowed time. You might (no surprise) get about twice that out of it if you ran it to failure. New bolt and your upper (barrel) should be good for another 10k or so, ammunition dependent. Quoted:
Quoted:
I thought more would be interested in this. I was maybe just a little surprised that the bolt already broke. A "standard" bolt is only good for about 6k...after that it's on borrowed time. You might (no surprise) get about twice that out of it if you ran it to failure. New bolt and your upper (barrel) should be good for another 10k or so, ammunition dependent. Sorry, I didn't mean to imply that all bolts will fail at round # 6,001. At ~6k rounds cracks start to form, especially in the lugs adjacent to the extractor; from that point on, even if it's 12k rounds, the bolt is on borrowed time. Per your source, even on milder firing schedules, nearly all bolts will show initial cracking at 6-10k rounds...and the bold may fail at any time or last for thousands of rounds. For training and/or range use, meh, as you say. You may choose to bet your life on it; others may not. |
| I did. The reason I ask is because I had a bad experience once with a Sig M400. Broke the stock bolt at 800 rounds and I was pissed. So I installed a new Bcm bolt and it last 250 rounds or so and broke, the barrel extension ended up being out of spec. I will never buy a Sig because customer service asked me "well how many rounds do you have through the rifle" and I told them about 800 and they told me that their warranty for their ar's was only 500 rounds. I will never buy anything Sig Sauer because of that shit. |
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