I have my first AR on order (Bushy rifle) and I'm picking up the odds&ends (mags, sights, clean kit, etc.) a little at a time while waiting for it.  I'm considering the ARMS-40L-P rear site.  Wondering what others y'all might reccommend and why.  Also, it seems that with the 40L-P I would need a .040" taller front sight post?  What's with that? Are there fold-down rear BUIS that I would not need the taller front sight post?  Is the front sight post and easy change-out?

Thanks in advance.

Troy rear flip up.

Troy with loctite

Troy

PRI

Troy is hard to beat.

I'm surprised nobody's suggested Troy yet. ;)

I have Troy on a couple carbines & love the positive lockup when deployed. For fixed sights, try LMT or LaRue.

Posted Via AR15.Com Mobile

Another vote for Troy BUIS, I have them on two of my carbines, I'm very satisfied with their solid lockup and quality.

Here's the differences between the Troy and the ARMS-40L-P rear BUIS:

The 40L's release/ capture lever are harder to manipulate because they're smaller and shorter than the model 40, the Troy have no release lever to flip up just pull it up, it have a slight resistance so it won't flop around, once the Troy's sight is up it is locked  solid no wobbles, to fold it press a button on the left side, the release button prevents it from accidentally getting folded.

The Troy when flipped up defaults to the large hole peep sight aperture, the 40L defaults to the small aperture, most shooters prefers the large hole in case the target's distance is close, it's easier to see with the large hole peep sight.

The windage adjustment are a little difficult to move with the Troy but it prevents accidental mis adjustment,  the 40L's adjustment are larger easier to move but also easier to accidentally changed.

Folded height from top of the rail to top of the BUIS, the Troy are lower:
ARMS 40L -  0.610"
Troy -  0.460"

The Troy are a little bit more expensive but worth it with all the desirable features, high quality of materials and workmanship.

With any of the rear BUIS brands you might need the .040" taller front sight post, try it out first and if you can't get it to zero and it still shoots high but your front sight post is all the way up, then you would need the taller front sight from Bushmaster.

TROY worth every penny

Troy's Diamond Sight

Superior to the Troy.

I like full adjustable buis, like the LMT.  When I switch to the .22 conversion, I just turn the dial 14 clicks up and gtg.

LMT is my preference, too, unless I have to make clearance for an optic.