I bought my very first ACOG, a TA31F last night brand new with the standard mount. I have a Magpul Pro flip down rear sight currently on my rifle. I went to mount the ACOG as far back as I could on the rail, just over top of the rear sight, and the front of the sight causes pressure on the scope. I thought it would clear it just fine. So now, I am curious, does this happen on any other rear sights? I would like to have the ACOG as far back as possible due to the little eye relief, and now I am considering buying troy’s. Any feedback here or has anyone else had this issue?
Its going to happen with all rear sights. Your solution is at hand. Its called the KRAM from Macedon Defense. Google them.
I’m pretty sure the Matech, KAC 600m, KAC 300m, KAC 600m micro, and KAC 300m micro will all fit under the rear of the ACOG.
Should I worry about this effecting POA or POI though, or is it a known issue that really is not a factor? I am brand new to the ACOG game.
The base that IG mentioned does work.
Alternately, the KAC Micro rear sights (25650) are built specifically to fit under the COG.
A dedicated USMC marked model (25650-1) are provided to the USMC for that exact purpose.
Alternately, the Matech and Troy rear sights work.
With a LaRue base it fits with KAC and troy buis in my experience.
I am unable to to do the back lock of the larue mount with a PRI rear buis.
I think I am going to sell the Magpul sight and pick up a Troy.
Where/how exactly is the rear flip sight interfering with/contacting the ACOG?
Do you mean that you have the ACOG moved back so far that the ACOG mount is touching the “base” of the flip sight (i.e., the stationary portion of the flip sight that doesn’t “flip up”) so that the ACOG mount can’t fully “seat” on the rail?
If that’s the case, I don’t think a different flip sight is going to help - that is, I don’t think any other flip on the market is going to allow you to move the ACOG any farther to the rear.
A different rear sight isn’t going to help. The OP mentions that he wants better eye relief. Yes, many sights will fit under the ACOG. But, it doesn’t change the fact that you can only move the ACOG back so far before it stops.
So the solution is a small riser (henceforth known as the KRAM) which goes between the mount and the ACOG and allows you to move the sight more to the rear and give you better eye relief (see pic).
In the event that anyone is curious, I have one on my personal ACOG (this is one of the original prototype 7.0 mounts) and yes it does work and I have not noticed any issues with it.
Short of the LaRue RCO mount (I have one kicking around somewhere in my unused-since-Afghanistan crap pile) which does a mediocre job of the same thing (but that setup basically precludes running BUIS under the ACOG - might as well run BUIS in front of the 'cog, or an offset micro RDS), that’s the best looking option I’ve encountered. That said, the stock TA51 mount can still be ran pretty stupidly far back, even up against KAC or TROY BUIS (I have one of each), the eye relief concerns I have with those optic setups have more to do with the glass than the mounting (but I know I can shoot pretty well, even with the TA31 installing my eyepro into my face).
How about a shorter stock? I’ve had 4x32 ACOGs for a long time, its 1.5" eye relief never bothered me but then I don’t use these scopes with A2 stocks. A fully collapsed SOPMOD stock is just about right for me. If that’s still too long, there are stocks shorter than the SOPMOD.
Either that, or mount a red dot sight, or red dot sight AND BUIS built into the ACOG, e.g. TA31ECOS.
The KRAM works as designed, it does raise the ACOG (designed to raise as little as possible), then you may not get a good cheek weld, but facial structures differ so it’s hard to say till you try it.
The LaRue LT 681 RCO mount is a great way to beat the eye relief issue with the TA31…
I have found that my TA31 ACOG mounted on Bobro mount will not fit on top of a Troy backup sight for which reason I got a KAC micro (which I like way more than Troy, except for price.)
With the TA31 on the LT681 the Troy Micro flip ups fit nicely.
I’m betting that the new Bobro Lowrider BUIS will clear once they go public.
http://www.ar15news.com/2015/01/07/new-bobro-lowrider-sights/
IMO it only really helps if you aren’t running a rear sight. That’s due to the single lever design. People should remember that the ACOG was designed to be mounted in the sight channel on an M16A1/2 styled rifle. The flat top was an after thought.
If you want to change the position of the scope, and you are running a rear BUIS, your only real option is to raise the optic and shift it back, which is what the KRAM does.
I definitely agree the best solution is to forego the rear BUIS.
The LT mount does elevate the optic and set it back on the rail, albeit at more expense than the KRAM I would imagine. I like the QD mount however as I also run an EOTech on this rail and like to be able to switch easily between the two.
By disclaimer, I must add that I haven’t tried the KRAM.
I concur, the LT RCO basically negates the ability to run BUIS - which is why mine is sitting unused in one of the ACOG ‘socks’ I have lying around instead of mounted on a carbine.
I did goof around with the TA51 a fair bit, and it does RTZ within 1MOA. I really didn’t think it would, but unmounting it and remounting it on my M16 produced no measurable change, and I was still making tiny keyed holes at 36yd and hitting just as accurately at 200yd (considering the accuracy cone of M855 probably dwarfs that).
Amusingly, I think the KRAM would work stacked on the TL RCO mount, but I’d argue that isn’t really required.
This is about the position that I currently have it sitting in. I was hoping I could have the ACOG mount basically one slot back, but it would be touching my BUIS. I am going to the range tomorrow, and just shouldering it around the house so far it’s not terrible in the position it’s at. After shooting if I still don’t like it, I will buy the riser setup that IG mentioned, or I will buy a LaRue mount. I am not crazy about the standard large knobs on the stock mount.
I will be adding an RMR when funds allow in the next month or so. Also to get the proper eye relief for me, I run my Magpul ACS-L extended one click. It’s not terribly uncomfortable, and the only reason I have kept this stock is how great the cheekweld is, but it is a bit heavy.