My new Bushmaster's rear sight is loose.  It will actually turn back and forth approx 3-4 degrees and at the moment is pointing about 3 * to the left.  How do I lock it back down? Thanks for the info

Sounds normal to me.  As long as when you turn it - it springs back to it's 'default' position.

This explains it all:

Armalite's Tech Notes, Number 18.

www.armalite.com/library/techNotes/tnote18.htm

"1. The rear sight of M16A2 rifles is spring loaded in such a manner that it tends to rotate counterclockwise, as viewed from above. This biasing is caused by a ball and plunger in the left wall of the sight base, which presses against a surface of the receiver and forces the base to rotate. This is a means of taking up accumulated slack in the parts of the sight. The spring loading insures that the sight is always in the same position, even if cocked somewhat to the side. Keeping the sights consistently in the same position aids accuracy."

"2. Depending on the buildup of tolerances, the cocking of the rear sight may be quite noticeable. While this may be somewhat unattractive, it is intentional, and is supportive of good accuracy. All M16A2 pattern sights display this cocking to some degree."


There is more, go to the site and read.

And once again, thank you Mark Westrom for the excellent resource material in your Armalite Library and Tech Notes.

Normal

Quoted: Normal

+1 what he said

But the new default position is cocked about 3 degrees to the left.  It is not straight in line w/ the rest of the rifle.  Are you guys saying that that is normal?
Thanks
Jay

Quoted: But the new default position is cocked about 3 degrees to the left.  It is not straight in line w/ the rest of the rifle.  Are you guys saying that that is normal? Thanks Jay

Its fine. Mine was like that.

Quoted: Quoted: But the new default position is cocked about 3 degrees to the left.  It is not straight in line w/ the rest of the rifle.  Are you guys saying that that is normal? Thanks Jay Its fine. Mine was like that.

+1

My Colt A3 carry handle and LMT fixed BUIS are both like that.

It's normal but if it really bothers you, sight the rifle in with the "Improved Battlesight Zero". That will tighten it a lot and keep it nice and straight.

groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw

It's normal, they all do that UNLESS you have one that is out of spec.  If it really bothers you, I suggest JB Weld and duct tape.  It's what Jack Bauer would do.

JB weld.

Quoted: But the new default position is cocked about 3 degrees to the left.  It is not straight in line w/ the rest of the rifle.  Are you guys saying that that is normal?

Yes.

Quoted: It's normal but if it really bothers you, sight the rifle in with the "Improved Battlesight Zero". That will tighten it a lot and keep it nice and straight. groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw

You sure about that?  I use the IBZ, and I'm pretty sure Forest (can't say Forrie, can't say Forrie) uses it, and mine still skews.

My armalite carry handle is straight.  My White Oak NM upper is straight too, but it's pinned.  you could send your upper to White Oak for pinning, but it's costly.

this is a decent DIY fix:  www272.pair.com/stevewag/arsight/arsight.html

Throw that copy in the river and buy a Colt.

Quoted: Quoted: It's normal but if it really bothers you, sight the rifle in with the "Improved Battlesight Zero". That will tighten it a lot and keep it nice and straight. groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw You sure about that?  I use the IBZ, and I'm pretty sure Forest (can't say Forrie, can't say Forrie) uses it, and mine still skews.

It worked with two of my rifles that I use the IBZ with.  They tightened enough to stay straight on their own but you can still move them to the default position with a little pressure.  

It's normal, but some guys just can't stand it.  I have welded up quite a few to get them to fit better.

Tony Rumore
Tromix Corp