I was just assembling my new Bushy M4 upper, and I noticed that even when the front sight post is positively locked into the front sight detent, there is still some play in the post.
Now, I'm not talking about a lot of slop, but it does still turn enough that I am not viewing the post straight on (i.e. its slightly askew).
I can't say that I've ever noticed this problem on my other ARs', and I haven't had a chance to drag them out of the safe for inspection.
So... does this seem normal to you guys, and can a slightly askew front sight post cause accuracy problems?
It just depends on the height of the front sight to the base. If the retaining ring is above the base, then you will have some problems with the post being loose. If the retaining ring of the front post is above the base, the cure is to install a new sight post with a higher pin. But if the retaining base is below the top of sight tower base and you still have a lot of movement, it helps to pull the front sight post, then apply a drop of Blue loctite to the threads and work it into the threads (you only want a fine film on the threads, not the threads covered). Once the loctite has dried, re-insert the post and re-zero. The dried loctite film will acts as a thread filler to keep the sight from dancing. Also, take your time when you start the post back in the tower threads; you don't want to cross thread the two. Also, use a sight tool; the post is going to be a bitch to re-insert with out it.