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Posted: 1/26/2013 5:30:29 PM EDT
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Hello all, I am trying to find a replacement gas block for my dad's optics ready Carbon-15 Bushmaster. The thing is, he bought it without really looking at what it had and really only wants iron sights. However the rifle came with a flat top and a low profile gas block. I was trying to find a gas block that fit this rifle that is a plain old front sight base. However, a .625" gas block is too large for this rifle. I took it to one of the local shops here and it was something like ~.590 diameter(don't recall exactly). Has anyone heard of this before? I have had zero luck finding a smaller gas block than .625" and am hoping I'm not SOL here.
If push came to shove I could definitely put a gas block with a rail on it, it would just drive the price up since I'd have to buy front and rear irons still which I'm trying to avoid but its doable if that is the only option. I'm a bit of a noob when it comes to actually modifying AR-15s so if I need to clarify I surely can. Thanks all. 
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Quoted:
"However, a .625" gas block is too small for this rifle." "I took it to one of the local shops here and it was something like ~.590 diameter(don't recall exactly). Has anyone heard of this before?" I think you lost me a little - if a .625" is too small then you probably need a .750" gas block. If that second part is true, then no, I've never heard of that and I'd be real surprised if BM used anything that non-standard. Sounds like you just need to measure for sure and see what it really is. YHM has some good combination gas block/flip up sights but they're only available in .750". Or like you said, use a railed gas block with separate irons that are a "gas block height". Or put a free float rail on over the existing gas block and mount your irons to that. Lots of options out there! |
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Quoted:
Quoted:
"However, a .625" gas block is too small for this rifle." "I took it to one of the local shops here and it was something like ~.590 diameter(don't recall exactly). Has anyone heard of this before?" I think you lost me a little - if a .625" is too small then you probably need a .750" gas block. If that second part is true, then no, I've never heard of that and I'd be real surprised if BM used anything that non-standard. Sounds like you just need to measure for sure and see what it really is. YHM has some good combination gas block/flip up sights but they're only available in .750". Or like you said, use a railed gas block with separate irons that are a "gas block height". Or put a free float rail on over the existing gas block and mount your irons to that. Lots of options out there! D'oh! I meant the .625" is too large sorry about that. Tried to actually fit one on and it was too large. Is it possibly Bushmaster uses some whacky size that isn't standard? Like I said I haven't been able to find anything smaller. Thank you for the reply!
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Can you precisely measure the diameter of the barrel where the gas block is to know for sure? (I'm just having a hard time believing it's .590", but need to know for sure). The part of the barrel in between the gas block pins similar to this:
http://i1179.photobucket.com/albums/x388/forester2/IMG_0962_zpse5224d8b.jpg |
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Quoted:
Can you precisely measure the diameter of the barrel where the gas block is to know for sure? (I'm just having a hard time believing it's .590", but need to know for sure). The part of the barrel in between the gas block pins similar to this: http://i1179.photobucket.com/albums/x388/forester2/IMG_0962_zpse5224d8b.jpg I can go back to the shop for sure if you think that I made an error, don't have calipers and I live in a tiny apartment haha! I didn't notice any obvious changes in barrel diameters, but then again all we tried to do was size it on the barrel without taking the original gas block off so I could've made a stupid there. Attached is the picture of aformentioned Bushmaster. Thanks again for the help Forester.
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I've been searching around the web and I did see one reference to someone putting a .625" gas block on theirs. If that's what it turns out to be then these would be a couple of gas blocks to consider, then you could mount a front sight to the new railed gas block. The other thing to watch is the height of the rail on whichever new gas block you end up using - some are the same height as the top of the receiver and take "standard height" front sights, while some are a little lower and take "gas-block height" front sights.
PRI gas block (rail is same height as upper receiver) YHM gas block (rail is lower, needs "gas-block height" front sight) Or this: PRI flip-up If your barrel takes a smaller diameter gas block than .625" then I'm out of advice! |
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Quoted:
I've been searching around the web and I did see one reference to someone putting a .625" gas block on theirs. If that's what it turns out to be then these would be a couple of gas blocks to consider, then you could mount a front sight to the new railed gas block. The other thing to watch is the height of the rail on whichever new gas block you end up using - some are the same height as the top of the receiver and take "standard height" front sights, while some are a little lower and take "gas-block height" front sights. PRI gas block (rail is same height as upper receiver) YHM gas block (rail is lower, needs "gas-block height" front sight) If your barrel takes a smaller diameter gas block than .625" then I'm out of advice! Yes sir, I'm going to try to get this gas block taken off and that part of the barrel measured, however I'm not hopeful. To be honest this Carbon-15 seems like a giant piece of shit but I know the old man won't shoot it much and just wants his iron sights like in Vietnam so the lower shouldn't crack on him haha. Really hoping Bushmaster didn't make some insanely thin barrel that they didn't even bother to make replacement gas blocks for but who knows. Thank you again for the help sir. |
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