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Eric
9 May 2008, 16:05
Item Reviewed: Brownells HK Style Flip Up Sight

Backup iron sights (BUIS) are mandatory for a weapon that uses some type of battery powered optic and preferable as a backup to other optics as well. Even though great advances have been made in the battery life of Aimpoint, EOTech and similar optics, there is still a chance that they may fail and thanks to Mr. Murphy, they will fail at the worst possible time. Luckily, the AR15/M4/M16 with a flattop upper and 1913 rail makes adding a BUIS simple.

Brownells is one of the best known names in the firearms industry and they continue to offer more and more accessories for this weapons system. I’ve been using their new HK Style Flip Up Sight for a while now.

When I first picked up the sight I noticed that it was fairly hefty. Components were cleanly machined from 4140 steel and 6061 T6 aluminum. The matte black finish is evenly applied. The four position drum has a .160” aperture for close-range engagements, as well as three .070” apertures for 100 yards, 200 yards and 300 yards, which are calibrated for M855 62 grain ball ammo.
http://img.photobucket.com/albums/v503/AR15forme/Brownells/IMG_31381.jpg
Installation was simple and secure. I appreciated the slot milled into the mounting nut on the left side. This allowed it to be tightened down with a coin or screwdriver, instead of a hex wrench. The cross-bolt on the underside of the unit engages a slot in the 1913 rail, adding more stability. When using a carbine with the correct “F” height front sight base, zeroing was straightforward. However, we’re still stuck with numerous manufacturers that are using rifle front sight bases that are the incorrect height. This caused the front sight post to nearly be screwed all the way out.
http://img.photobucket.com/albums/v503/AR15forme/Brownells/IMG_31501.jpg
I’ve had the opportunity to use this BUIS on a few different weapons, with either an Aimpoint or EOTech optic in place. It was also used as a stand-alone rear sight, with no optic in place. This BUIS is easy to deploy and it solidly folds into the up and down positions. While there isn’t a provision to lock the optic in the up position, I didn’t experience any issues with it folding back down until I intentionally did so.

I’m more accustomed to peeking through a more traditional type rear aperture, yet I found that I didn’t have any problems finding the front sight with this unit. The majority of my shooting was done with the larger aperture, which is a bit smaller than the larger A2 type aperture. I did use the 100 yard aperture a bit, but have no use for the 200 and 300 yard settings. Windage adjustments are made by way of a standard A2 style knob on the right side of the BUIS. Each click is a half MOA of adjustment.
http://img.photobucket.com/albums/v503/AR15forme/Brownells/IMG_31451.jpg
Overall, I liked this BUIS a lot. However, I can think of a couple modifications that would make it even better for my use. The mounting nut protruded too far, which occasionally interfered with the rapid grasping of the charging handle. I’d like to see the same style of nut used, but just a lower profile one. I’m also a big fan of A1 style detent adjustments on iron sights. While these require the use of a tool or FJM bullet-tip for adjustment, there are less likely to get knocked or otherwise moved out of adjustment. I don’t think that most users will utilize the 200 or 300 yard settings on a BUIS. Perhaps the apertures could all be set on the same plane, using a full size A2-size aperture (.200” I believe), the .160” aperture and the smaller .070” aperture.

It looks like Brownells has added another good option to the backup iron sights that they already offer.
http://www.brownells.com/.aspx/sid=51853/sku/360_Series_Flip_Up_Rear_Sight
http://img.photobucket.com/albums/v503/AR15forme/Brownells/IMG_31491.jpg

Stickman
11 May 2008, 17:24
When Eric first mentioned the "CAR-15/M4 360° HK STYLE FLIP-UP SIGHTS" sights to me, I'll admit I was less than ecstatic about another pair of HK style sights hitting the market. However, since I was going to be doing a few days worth of heavy caarbine training, I figured it would give me a chance to point out all the reasons I'm not found of this style of BUIS.

Once again, I find that things I've not been found of in the past have been improved upon. One of the largest sticking points with me is that I feel the sights should have a varying set of apertures instead of just the tiny ones calibrated for elevation. Indeed, this concept stayed with me throughout the testing, but instead of it being a major point, I found that for all my close in work I used the largest aperture ( .160") anyway, and that it made little difference. When working hanging bowling pins to simulate engagement of moving targets at distance, I found that the smaller aperture (.070") wasn't anywhere near as bad as I thought it would be. In fact, I found myself liking it quite a bit. The small size makes for solid precision work, and the larger size works well for closer in.

This left the 200 and 300 yard apertures. Since there was no difference in size, it left you with a pretty simple method of estimation, and dialing in your BUIS to your chosen distance. Again, this isn't my favorite method, but I found it worked well. For some reason I keep thinking that varying size apertures would work better, but the current layout worked well.

The BUIS is designed to work with the standard "F" front sight base, and is set for military M855 (62 grain) loads. As with any BUIS, you need to dial it in to your own particular loads and go from there. I found it worked nicely with the ammo that I fired, which was 55 grain FMJ.

The sight feels solid, and turning the dial/ knob wasn't hard, but wasn't soft enough to invoke concern of it being moved accidentally. I know that some people will wish it locked into the upright position, but it wasn't the end of the world for me. The BUIS was easy to fold into its upright position. I had no issues with the knob on the side, though I can see why Eric points it out. The knob allows for easy tightening, and I had never any issues with it coming loose. I through it on several different weapons through out the testing, and used a coin or knife blade to tighten and loosen each time. The large slot makes it an easy process.

For HK fans, this BUIS will be something they love. After all, it brings the convenience of a folding rear sight along with the HK style diopter that they love. For other shooters, while it might not be love at first sight, this unit is very functional, and I would have no problems using it on my carbines.


http://stickman.rainierarms.com/galleries/Optics/IMG_2769%201028%20WEVO.jpg


http://stickman.rainierarms.com/galleries/Optics/IMG_2765%201028%20Stick.jpg

Stickman
11 May 2008, 17:33
http://stickman.rainierarms.com/galleries/Optics/IMG_3548%201028%20WEVO.jpg