Just put an E O tech 551 on my RRA Tactical. I have a DPMS rear sight on it. It co witnesses really nice, but I hate the view. Shit can the rear sight or keep it? I can't decide, these things are all but failsafe, tough as nails, what do you think?

Shit can. What are the chances that the Eotech will go down?

Mine's down now.  If I hadn't put iron sights on it, it would be a bat.  Murphy's law.  

I don't cowitness the EOTech (when it works) generally.  But I've done it through the AIMS #40 and the BM flip up front sight, and it works just fine.  I'm not against it or anything, I just don't see the point.  It's just more junk to look at?  But that's me.

But if you did want to do that, could you maybe change the picture by switching rear apatures or something?

I plead guilty to being "old school" but I just don't trust anyghing with batteries.  That is to say, I "trust" (or I wouldn't be using the EOTech), but "verify."            

Put the #40 behind it and it is folded out of the way untill you need it when the batteries die, as they all do eventually.
Jack

If you are focusing on the target with both eyes open, you really shouldn't notice the iron sights at all.  I don't, but maybe that's just me.  

Spoken like a man who's EO Tech is going to fail very soon [:)]

While the chances may be low, the chance still exists. Everything will fail and it will fail at the worst possible time. Let us not forget that the purpose of the BUIS is in case the sight [b]"stops functioning"[/b]. A sight can [b]"stop functioning"[/b] from either electronic, mechanical or electrical failure. ICs fail, switches break and batteries run out of juice. In the real world, these things happen.

If you're just plinking at the range, do what you want. If you ever need to depend on your rifle for your life, keep it on. Better to have and not need, right?

I agree!  Get the ARMS #40 or MADD flip up rear sight.  At least you have it when you need it then.  If the front post bothers you, there are decent flip down front sights also.

SWITCH TO A FLIP UP REAR SIGHT. BUSHMASTER FLIP UP REAR SIGHTS WORK GREAT AND ARE LESS EXPENSIVE THAT MOST OTHERS.

I went without back up sight with eotech on my flat top.  At last 3 gun match, almost completed the stage, was working from prone at targets 200-240meters when my eotech falls off and is laying on ground beside me.  Shooter done.

So now I am taking my christmas cash and either going with arms #39 to mount to handle to allow co-witness or arms 40 to have the back up flip sight.  I am now believer in back up sights.

bigtwinhog

WTF!!  How in the hell did it just FALL OFF??  Never seen that happen before.  Try two things,  crank on that screw an little tighter and if that doesn't work, LOCK TIGHT.  Still get BUIS though.

Dot sight failure is the least of your worries (although my Eotech batteries failed without the warning flash just recently! :-0).

Go out and shoot on a bright day. Got that dot (Aimpoint, Eotech, etc.) adjusted good for those targets in shadow? OOPS, that next one is in bright daylight. Now where did that dot go? GONE. Too bad, washed out by the bright target. Please wait Mr. Bad Guy, I've got to turn up my dot (or deploy my irons)!

Go out and start shooting around dusk and work into the night. Your Eotech winds up turned down nice and dim so you can see those low contrast targets (hell, I use the top of the NV range with my naked eye). Finally it's really dark and there's the one you can't see but you know is there, so you hit the pressure switch on your light. OOPS. There's the target, but where's the dot? Aw, too bad, it's gone, washed out by the brightly lit target!

Leave your BUIS deployed. Sight through it when you can, which is almost all the time. The dot will still be there. When it's too dark for the aperture, just move your cheekweld back and up a bit and your dot will appear between the top of the BUIS and the top of the dot-sight FOV. When it's too bright for the dot, use the irons. When your dot is turned up too high, well, you're screwed, so err on the side of too dim.

Next time we have a defensive rifle match at the club I'm going to suggest that no dot brightness adjustments be allowed prior to each COF. Time required to fool with sights should be part of the score.

It's beyond me why we don't yet have dot-sights with automatic brightness control like the old Elbit Falcons had.

The BM sight has a serious falt, if it gets bumped by a sleeve, brush, etc. it falls over dead and doesn't go back into battery.
Jack

The EOTech low battery warning does not work with lithium batteries due to the manner in which they die.  

Lithium batteries maintain a constant voltage until they can no longer sustain it and then they just drop.  With a standard alkaline battery, the voltage drops as the battery dies, thus the low battery warning can be triggered.

Thanks, that's really good to know since all I use for 552 are lithiums!  I think EOTech needs to find a way to the low battery signal work with lithiums...

That's exactly why I'm going w/an ARMS 39 on an A2 upper on my new rig...If it can go wrong it will-to me.

Very true, Red-Leg, which is why I was using alkaline batteries. For the record the sight in question is a 551.A65 using N-cell alkalines.

My post-mortem on the battery issue revealed that one battery had suffered an internal failure of some sort as evidenced by a reading of negative 150mV. The battery was approximately 6 months old and probably had a 1000 rounds or so under its belt. It must have been damaged by recoil and self-discharged over the last 2 weeks since it was last used.  The other battery was reading approx. 1.4V, still well within the usable range.

The good news was that I was prepared: with spare batteries, by catching the problem during "pre-flight", and with my trusty BUIS, which I didn't need because of battery failure, but sure did as the sun went down and I had to continuously transition between flashlight and low-light during training.

What these guys said, but in picture form. The folded away ARMS 40 doesn't get in the way. if you don't need it, it's there anyway. If you do, well..flip it.

something just occurred to me. With an Aimpoint, mounted to the forward most part of the flattop, it seems like it would work like a giant ghost ring. I wonder if you can do that with an EOTech as well--center it in the rectangle, and let loose.

[img]http://www.hunt101.com/img/057181.jpg[/img]

Absolutely! Especially at CQB ranges, say less than 7M. If you've got dot failure, either because of batteries or lighting conditions, just center the front site tower in the window and have at it. A few of us actually practiced this 4 weeks ago. It works like a charm, and is a good argument to stay with the normal front sight and not a folding one.

The trouble with a fixed BUIS and the EO is that the "co-witness" height is at the mid point of the reticle.  If you keep a tight, iron-sight cheek weld, the lower half of the reticle is full of sights or near the top edge of the window.

If you remove the rear or get a flip, the EOtech reticle is either on the sight post or near the upper edge of the window, so I don't think you really gain much.

The advantages of a BUIS have been covered, so it is a no-brainer to have one of some sort.  Work with your current set up and see if you can get used to it.  Try it with the DPMS removed to see if you actully like it better.  If you do, sell it and buy and ARMS #40.

Prior to my ARMS 40, i ran the DPMS and a Reflex for 3 gun matches. I liked the constant co-witness, but have since sold off the DPMS, bought a 40, sold off the tritium sight, and bought several red dots (Comp M2x2, Comp ML2, EOTech 512, and finally, 552). I am still getting used to no fixed rear sight to look through. It's almost like a leap of faith for me that the red dot is centered and ready to go, with no rear frame of reference!

[img]http://www.hunt101.com/img/015027.jpg[/img]