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Posted: 10/31/2011 6:20:04 AM EDT
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Just curious: How tough would it be to deform, break, or otherwise knock off zero a fixed FSB with taper pins? |
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Quoted: Quoted: Just curious: How tough would it be to deform, break, or otherwise knock off zero a fixed FSB with taper pins? extremely We talking like setting off dynamite next to it, throwing it out of a helicoptor at 500+ feet, or we talking like dropping it on a rock? |
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Just curious: How tough would it be to deform, break, or otherwise knock off zero a fixed FSB with taper pins? extremely We talking like setting off dynamite next to it, throwing it out of a helicoptor at 500+ feet, or we talking like dropping it on a rock? The aluminum receiver will break long before the steel FSB and pins. |
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The standard pinned FSB is immensely strong, I found out unintentionally.
I was one of the early adopters that put rifle length KAC FF RAS handguards on carbines back in 2000s. All of my barrels had standard FSB, their tapered pins can be difficult to remove, especially when you don't have the special tools and a big hammer. Moe than once I'd resort to cutting the FSB off with my Dremel tool, but I usually give it a fair shake before doing a destructive removal. I'd cut as little as possible, then after driving the pins out, I'd often have to use a hammer to knock the FSB off the barrel. I'd hammer the crap out of it, its triangular shape stands up to repeated blow very well, its shape would not change, hell couldn't even see dents. I missed with the hammer and the strike ended up on the KAC rail, the rail deformed immediately 
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The forged sight base is very strong. The front sight posts bend all the time. Meaning the front sight itself? Shouldn't that be protected by the ears of the FSB? those bend as well. Even the clamp on FSB have had the barrel twist in the upper before the clamp on fsb moved on the barrel. |
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Quoted: Quoted: The forged sight base is very strong. The front sight posts bend all the time. Meaning the front sight itself? Shouldn't that be protected by the ears of the FSB? While the ears offer some protection I've seen far more bent front sight posts than broken ACOGS. It just doesn't take much to bend them. I feel the HK style ears/wraparound protection is better. If given the choice I will take the HK style front sight every time because of this. |
| Very strong! I had an Oly K3BM4 pop out of a vice block (don't ask) and fall about 5 feet to my concrete shop floor...landed right on the FSB left ear....as you might know these are cast FSB's...I picked it up to find no damage to the ears...there was a teeny tiny chip in the concrete where it hit. I was utterly amazed (and thankful) at the results. After witnessing this..I would opt for a fixed FSB on any combat rifle if given the choice. I love my Magpul MBUS sights..but I will be damned if they could take similar punishment. |
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I saw a M4 barrel with a broken front sight base down at Davis-Monthan AFB. I have no idea who or what did it in though. One of the legs of the A frame was cracked all the way through and was h seperated from the base. No more than proof that junior EMs can break *anything.* 
~Augee |
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Akin to what Dr. Ian Malcom said about life in Jurassic Park, PVT Joe Snuffy...finds a way.
A common place for a Bradley driver to place his M4 when opening the power access door (hood) of his vehicle is just above the hinge as it is flat and out of the way. With the addition of Bradley Urban Survival Kit (BUSK) comes tons of reactive armor which greatly reduces the amount of space at the aformentioned part of the vehicle. If a rifle is placed in that spot and the power access door is opened, the reactive armor can and will pinch the rifle and crush it like a beer can. The door alone weighs about 800lbs and with the armor is pushing 1300lbs and has super strong hydraulics lifting it. The rifle never saw it coming. Oh the joys of a 0300 Kuwaiti morning. |
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Very strong! I had an Oly K3BM4 pop out of a vice block (don't ask) and fall about 5 feet to my concrete shop floor...landed right on the FSB left ear....as you might know these are cast FSB's...I picked it up to find no damage to the ears...there was a teeny tiny chip in the concrete where it hit. I was utterly amazed (and thankful) at the results. After witnessing this..I would opt for a fixed FSB on any combat rifle if given the choice. I love my Magpul MBUS sights..but I will be damned if they could take similar punishment. The FSB ears DO dent when it encounters/hits another steel material. Concrete can't dent/deform the FSB ears. |
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Just curious: How tough would it be to deform, break, or otherwise knock off zero a fixed FSB with taper pins? extremely Yes. You'll break the upper before the FSB to barrel interface gets damaged. Also I had to literally drill out the pins on my Stag. We couldn't get 'em out with an arbor press! Does anyone have a link to a good clamp-on A2 style FSB incidentally? I'd like to put that barrel back in service. |
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Ok, i have a question in relation and maybe adco could help me out....
I took off my FSB on my new upper to install my DD barrel nut. The pin holes in the barrel seem different. The rearward hole is partially open. The pin is still very tight but part of the hole is open as if it is too shallow. Its a standard gov profile middy, not m4. Is this anything to be concerned with? The forward pin hole is completely enclosed but like i said....both were very tight going in and out Don't mean to hijac, just seems relevant |
| I posted a similar thread a while back asking if anyone had ever had/seen a broken FSB. only one person responded yes, and they said it was a military guy jumping out of a helicopter, who landed on his M-4 instead of his feet, with the FSB being what took the impact,and the FSB cracked. So not only did in take the weight of the rifle falling out of a helicopter, but the weight of the soldier falling on top of it too, and landing directly on the FSB, so yeah, it takes a hell of a lot to break one. |
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The forged sight base is very strong. The front sight posts bend all the time. Meaning the front sight itself? Shouldn't that be protected by the ears of the FSB? While the ears offer some protection I've seen far more bent front sight posts than broken ACOGS. It just doesn't take much to bend them. I feel the HK style ears/wraparound protection is better. If given the choice I will take the HK style front sight every time because of this. Actually, they're easier to crush or knock out of round. I've seen a couple complete circle sights on milsurp rifles like this. If you can get the FSB to move under normal circumstances, even just enough to be able to see it, you've probably done catastrophic damage to the barrel or receivers. |
| FSBs are fairly easy to knock off of zero when they are installed with non-taper pins.... and I have moved FSB with taper pins too, but it is much more difficult. They are not as "Rock solid" as people would like to have others believe. I would sooner trust a properly installed VLTOR VST clamp-on. |
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Very strong! I had an Oly K3BM4 pop out of a vice block (don't ask) and fall about 5 feet to my concrete shop floor...landed right on the FSB left ear....as you might know these are cast FSB's...I picked it up to find no damage to the ears...there was a teeny tiny chip in the concrete where it hit. I was utterly amazed (and thankful) at the results. After witnessing this..I would opt for a fixed FSB on any combat rifle if given the choice. I love my Magpul MBUS sights..but I will be damned if they could take similar punishment. The FSB ears DO dent when it encounters/hits another steel material. Concrete can't dent/deform the FSB ears. Funny. Wrong, but still funny |
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Just curious: How tough would it be to deform, break, or otherwise knock off zero a fixed FSB with taper pins? extremely Yes. You'll break the upper before the FSB to barrel interface gets damaged. Also I had to literally drill out the pins on my Stag. We couldn't get 'em out with an arbor press! Does anyone have a link to a good clamp-on A2 style FSB incidentally? I'd like to put that barrel back in service. Armalite, CMMG and DPMS have clamp on FSB's |
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