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Posted: 4/16/2011 7:51:41 AM EDT
| hello again, I am planning on changing from a carry handle upper to a Flat-top on my BushMaster XM15-E2S .most of the new Flat-Top uppers state that they have an M-4 ramp, will this work for me? oh another question, I am also going to replace the gas block with a low profile. should I use an adjustable one? or is there no need? Thanks again. |
| Well darn, I already have a L.P. Gas Block, and it is Aluminum, so Don't use it? buy a Steel one? also, if I just leave the regular Gas Block/Front Sight, would I be Un-happy? does it get in the way with ALL optics?I see alot of Rifles come with Flat-Top & a front Sight.as far as the M-4 Barrel cut-out, how do I know if I have it on my Barrel?and for clarrification, if the new upper has M-4 ramps & barrel does Not, I cannot use the upper with? Thank you for any & all Help. |
I can only answer part of you question. The FSB doesn't get in the way with most optics as you will usually need some sort of riser (or extra high rings) to mount under the sight. If it is a scope I needed a riser to access the charging handle.
This is without the riser, haven't got around to taking one with it on for some reason. I have since put a .83" riser on this. You can not see any of the front sight but pulling the charging handle is a PITA. With a red dot or holo sight you use a riser or mount to raise it for co-witness. |
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Quoted:
Well darn, I already have a L.P. Gas Block, and it is Aluminum, so Don't use it? buy a Steel one? also, if I just leave the regular Gas Block/Front Sight, would I be Un-happy? does it get in the way with ALL optics?I see alot of Rifles come with Flat-Top & a front Sight.as far as the M-4 Barrel cut-out, how do I know if I have it on my Barrel?and for clarrification, if the new upper has M-4 ramps & barrel does Not, I cannot use the upper with? Thank you for any & all Help. The FSB doesn't get in the way at all. The armed forces have been using optics with the FSB still in place for a few years now, it works just fine. With red dots such as the Aimpoint, you just ignore the front sight entirely when using the red dot. With magnified optics you may see a faint shadow at lower magnifications. As for the feed ramps 
ETA: Do not use a barrel with rifle ramps on an upper with M4 ramps, that would be the combo listed in the image as bad. It creates a shelf that rounds can get hung up on. The aluminum gas block could work, but it's not ideal. It expands at different rates than the barrel and could cause issues. Also, it's not at all difficult to cut your current FSB, turning it into a low profile gas block. |
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