First of all, I want to say that these sights are sweet!  I installed mine tonight and am very pleased.

Anyway, my question is are the clamp-style sights susceptible to movement if hit from the side (i.e. drop the rifle, hit a tree, etc.)?  They are only held in place by friction so how much can they really take?

Since I have a Bushmaster barrel and they don't park under the front sight tower, perhaps the PRI will just rust itself in place.  

I havn't heard of any problems. Just make sure you tighten the socket heads up real tight. Lock tight doesn't hurt either.
Good shootin, Jack

I thought the pivot point of the sight would be the weak link?

It probably would be for a frontal blow, but what about a blow to the side of the gas block or sight itself?

What's the newest PRI, the 4 set screw or the 2 clamp screw?  

Which design did PRI settle on?  

Which is easiest to install?  

Which is moving the least?

I'm pretty anal about making sure scopes and sights are lined up perfectly in relation to the barrel. Is there a tool to allign or index the front sight tower on an AR barrel?

[b]SULACO2[/b]...the clamp style is the newest design.  Both the set screw and clamp styles are being fielded by PRI.  I can't speak for the set screw style, but the clamp style is very, very easy to install.  You literally slide the sight on and tighten it down.  It took me longer to get the gas tube roll pin in than it did for the rest of the install.  I would assume the set screw style is less prone to movement as the set screws actually bite into the barrel.  The clamp style appears very solid, though, hence the reason for my question.

[b]bvmjethead[/b]...I just used the Mark I Mod 0 Eyeball.  [;)]

[b]3rdtk[/b]...will the Loc-tite (blue I assume) break loose when the assembly gets hot?

Me too.
The standard front sight is pinned on and the only way to fix a canted sight is to get a new barrel, OR do what I'm doing and order a clamp-on [i](like the PRI pictured above)[/i] A2 front sight from Armalite.
I'm making a Dissy barrel so I've milled the original front sight and need an additional front sight, but if yours is canted (rear sight extreme left or right) I'd call the customer service department of the manufacturer you got your AR from and ask them to warrantee it for manufacturer defect.

How does the PRI lock into position?  Do you have to push a release button or is it locked in both positions by a ball/detent?

[img]http://www.hunt101.com/img/059764.jpg[/img]

When you push the button on the left the "head" on the right pushes out.  There are 2 raised pieces on the inside of the "head" that engage notches in the sight.  You can see it pretty well in the picture.  Another advantage is that there is a slight angle to the engagement surfaces so if the sight is hit from the front it will fold versus breaking something.  It's very solid, though, and won't fold under normal use.

Brad D

The blue stuff won't break loose unless it is heated and your turning an allen wrench at the same time.
Good shootin, Jack