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Posted: 6/9/2008 9:32:31 AM EDT
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I recently purchased a stripped colt 604 upper, and I'm wondering if the "F" marked front site bases are what will work with this. I only ask because I've heard of people putting modern colt M4 barrels on their guns and the front site base is too low for use with a standard a2 receiver. |
It's a popular misconception over on the other foums that the .04 higher sight point is only for flat top M4 type carbines. Colt probably fed this notion by labeling the barrels w/the higher base "F". We retro nuts figured out long ago that, if it's a carbine or SMG, it'll need a higher front sight. Prior to the advent of the M4 as standard issue for the Army, it was done w/the ghigher post. When the M4 was adopted, I guess someone figured that it would be easier to just raise the base by that amount. For a retro piece, the "correct" front sight would be a standard height base with an .04 higher post. The originals were higher, thinner versions of the standard round posts of that era, but all I think you can get now are the current square posts; from Bushie, DPMS, and yes, even Colt. I've still got one of the original posts in my parts box. Came on the SP1 carbine I XM177E2d 30 years ago. Changed it over to the current type to give me a uniform sight pic on all my ARs. |
OK gents, I have searched high and low for the .040 taller round sight post, and have turned up nothing. Didn't see them on the bushmaster site either. And the proper FSB for a pencil barrel without the bayonet lug is being a real pain too. Of course, I am sure to find them right along side the 11.5" 12 twist barrel that has been so elusive to me!  (lol) Any ideas on where to look?
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If you're mating a bbl with your 604 upper, you do NOT need an F-marked front sight base. F-marked front sight bases are for use with flat-top upper receivers, not standard M16/A1/A2 versions. Edit: or at least I thought so? |
it is for flattops (M16A4 and M4/M4A1)and CARBINE gas systems barrels regardless of the upper on it. |
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