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Posted: 3/6/2005 4:00:53 PM EDT
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I called M1S the other day because I've been having trouble sighting in my 16" AR with the detachable carry handle (shooting rediculously high at 100 yards). The guy I talked to told me it was because my upper was probably assembled using a mil-spec upper reciever which has the rail machined slightly higher than a "civilian-spec" upper. He said to send it back and they'd switch it out. I've never heard of any difference in uppers. As far as I knew a flattop upper was a flattop upper. Can anyone enlighten me? P.S. Mods, if this is the wrong forum for this, please move. Thanks everyone. |
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Alot of carry handles are designed for the "F" stamped FSB that comes on Colt barrels. The shelf that the front sight post sits on is 0.040" higher on these "F" FSBs than on standard FSBs. I'd bet your next check that your M1S barrel doesn't have an "F" stamped FSB. Anyway, without the proper height FSB, your rifle will shoot high, in your case ridiculously high. The fastest solution to this is the 0.040" taller front sight post that Bushmaster sells. IMO, sending the upper back to M1S will do nothing for you. You'll get it back, sight it in and it will be high, unless they change out the FSB or the front sight post. |
| Thanks for the replies guys. Switching out the front sight post makes a lot more sense than switching the uppers. I assume that buy doing this it would also work with any sort of backup iron sight that I might put on it eventually. I've been thinking about exchanging my M1S detachable carry handle for a BUIS. |
Any aftermarket BUIS, like ARMS, Troy or KAC, will have the same problem and will need the taller front sight post also. |
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