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Posted: 4/21/2007 8:43:41 AM EDT
| I bought 3 original Colt M16 1/12 20" A1 uppers from CDNN a year or so ago. I just got them out to clean and adjust for a build and noted that my front site tool (the Brownell's high dollar one) will not fit into the 5 slots on the front site posts. I have depressed the detent and used dental tolls, etc to riotate the site, but it is too stiff on all them without using a tool. I have removed/adjusted A2 site hundreds of times and know how it should work. The USGI tool I had sheared two of the tool posts off (seemed like weak white metal) , so I got the high strength Brownells. There may be slight rust or solidified oils in the front site area making it stiff to remove/turn; but I can't even get the tool to properly engage the cutouts. It is like the diameter of the front site is somewhat bigger thean the diameter of the USGI or Brownell's tool. Any one else ever have this problem? Any solutions or thoughts? |
| first post yay... anyway I'm a gunsmith at my local Israel Defense Force, and have had this problem with some of my guns too. i just use a heck of a lot of gun oil, and try to depress the detent with a dental tool and a light hammer, just to get it moving at least, in my opinion its just some dirt. maybe that could help. I'm pretty lucky, because i get the official Colt tool through IDF :) |
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ETA: whoops!  Thought he meant the A1 rear sight assembly
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+1 Spray some penetrating oil on the FSP detent and FSP. Let it work for a while then try holding the detent in and removing the FSP with needle nose pliers. Once everything is apart you can clean, inspect, lube and reassemble. |
| not having much luck with the round post and pliers. I am afraid of marring the FSP. Was there two seperate A1 front site tools for the 5 detent post? wonder why the brownell's tool won't fit? Will a A2 4 detent post fit if I remove and damage this A1 round post? |
Hey, welcome to the board ! Mr. First Post ! |
Yes. Also, see: AR-15 sight mods |
Hell, the A2 post will work even if you don't damage the original  And I personally recommend the changeover. There's a reason the military went to a square post rather than that tapered round thing. Far easier to get and hold a good sight picture with the current square piece.In fact, the only "non original" type pieces on my M16. M16A1, and XM177E2 clones are precisely those front posts. 
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