AR Sponsor
Posted: 7/8/2010 1:38:40 PM EDT
|
I just discovered a problem with a new RRA Entry Tactical I just purchased. I have the standard RRA flat top upper and the standard half length RRA quad rail. I tried to move my ACOG forward on the flat top portion of the rail far enough to allow my flip up BUIS to work. I discovered that the transition between the flat top portion of the rail and the quad rail does not maintain the proper Picatinny interval and the bolts on the ACOG mount that mate with the rail grooves do not align. This seems like a major issue to me, what am I missing here? I mean, how could you possibly mount an Aimpoint or a EOTech on this rifle w/o having the thing basically right at the stock end of the rail?
This is the email I sent to RRA and below is RRA's response; "I have a RRA Entry Tactical with a RRA free floating quad rail. I recently installed Troy flip-up BUIS. This necessitated moving my ACOG slightly forward. When I attempted to do this I noticed that the ACOG mounting bracket would not fully seat on the rail. After examining the rifle closely I noted that when the rifle rail transitions to the quad rail, the grooves in the Picatinney do not maintain the proper interval when transitioning between the top rail of the rifle and the quad rail. I cannot mount the ACOG partially on the top rail of the rifle with the forward portion of the ACOG over the quad rail as the locking pins on the ACOG mount do not line up with the grooves on the quad rail. This means that either the ACOG needs to go fully over the quad rail, which produces too much eye relief for the ACOG to be used correctly, or forces me to mount the ACOG fully on the top rail of the rifle w/o leaving space for the BUIS. Why is this and what can I do (short of buying a new quad rail) do correct this?" RRA Response; 'We don't offer anything to correct that. All of our uppers are made the same we just recently started making the quadrails so they will match right up with the upper and not have a space for the jam nut. There is not a quad rail that will fix your problem because that is on the upper. Unfortunately I don't have anything that will make it work the way you want it to work." |
|
Well, error or bad design, or design limitations, not sure. That is why I am posting here, to get other opinions. I do not want to lash out and find out I am wrong. Basically nothing can be mounted on an RRA that spans both the flat top rail and the quad rail. You can mount something on one or the other but not on both.
I don't know, am I missing something here? |
|
If I am reading what you are saying there. I think that is normal.
You're thinking that the "handguard" rail and the "upper" rail should maintain the same spacing between them (the open air) as the picatinny spec? I would say that is not normally the case. I generally avoid mounting an optic on the rail, especially a free floating one. |
|
FWIW, I don't think "bridging the gap" between the upper receiver, and the quad rail is a very good idea. The rails do flex very small amounts, and this can have a negative effect on keeping a consistent sight zero. The ACOG will often (depending on the model) interfere with the rear flip-up BUIS, and keep it from being usable while the ACOG is mounted on the upper receiver. This is why many, if not most, of us use a quick removable mount of some sort (I use a LaRue mount) for the ACOG. An Aimpoint will not (typically) interfere with a rear BUIS.
Take a look at the optics pictures threads, and I think you will see what I mean. http://www.ar15.com/forums/topic.html?b=3&f=18&t=493306 |
| I also have an RRA Entry Tac and just recently put a DD Omega rail in with the same result, although it is not an issue for me as I'm using an aimpoint mounted all the way forward on a QD LaRue mount. I would guess this is why companies put out monolithic railed uppers |
|
I have done quite a bit of asking around about the issue and while not uncommon, it is regarded as an issue. I think even RRA admits it is an issue since they are changing their production methods so this issue no longer remains. I am more used to an Aimpoint or an EOech and this is my first ACOG, and I doubt this would have been an issue for either of the former. It's just the longer base of the ACOG brought this issue to light. If I were relying on this particular rifle in the line of duty there is no way I would mount the ACOG w/o a quick release mount
If I had known about this issue I am pretty sure I would not have purchased this rifle. After spending two grand between rifle and optics, I now find I am limited in terms of my configuration flexibility. |
|
Quoted:
I tried to move my ACOG forward on the flat top portion of the rail far enough to allow my flip up BUIS to work. I apologize if I'm not understanding the issue correctly, but just to expand a little, you can not co-witness iron sights and a magnified optic. It just won't work. Therefore, it does not matter if your rear BUIS will flip up, or not. You will have to remove the ACOG in order to use the BUIS sights, anyway. |
| Actually, damn good point. I am thinking in terms of EOTechs and Aimpoints. But the fact remains you cannot mount them where you want, since the rails do not line up. You cannot move your Aimpoint up, but your point on the ACOG is spot on, hadn't thought of that. |
AR Sponsor