Flat top AR's and ideal scope height

#1
Hello all, I have a nagging question that I have not been able to find a sufficient answer to regarding scope height for flat top AR pattern rifles.
I have struggled to get comfortable behind the glass on my rifle, but after a few different set ups, still don't feel like I'm there. I actually feel less sure about my direction of travel than before.
I started out with some 1.375 height 30mm rings to mount my 3.5-15 X 50 scope. My biggest problem seemed to be I did not have enough eye relief. right behind to that, I had to float up off the M16A2 style butt to get a good sight picture at higher magnifications.
It seems a majority of internet people with flat top AR's recommend and reference the military standard 1.4" of rise.
I feel like even at 1.375 I was too high and have since changed over to a 1.125 rise 20 moa cant unimount. Even still, I feel like it's not low enough for a proper weld, but the objective is just above the hand guard.
I would like to try a small (1/8") comb if I could do it without interfering with the charging handle.
Am I crazy? Way off? Is my problem my technique?
 
#2
For me it depends on the type of optic and the role of the rifle.

So do you feel as though irons are too high for you on an AR?


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#3
That's a good question. The last time I shot an AR with irons, I was at the level of sophistication of basically blasting away at washers, beer bottles and whatever had been drug out of town. I'll have to get behind one just to know now.
As for the purpose of the rifle and optic:
I am interested in making accurate long range shots and learning how to properly do so.
Right now, I have had no formal training, so I basically target shoot from 200-700 yards. I really enjoy shooting steel, but look forward to having the skill to take elk at distance.
To accomplish this, I would like to enroll in a long range class and have the equipment nessicary to be able to properly learn, without fighting my setup, and/ or not even having something I can work with.
Thank you for your response.
 
#4
I was a little too slow to edit but, I just noticed you specifically asked what type of optic. Night force NXS 3.5-15 X 50 MOAR reticle in MOA
 
#5
As general advice mount the optic as low as you can. Obviously a bigger objective scope has to be higher than a smaller one. Only way to get it lower would be to go with a smaller objective scope. Up and down would affect your cheek to stock but shouldn’t influence eye relief.

Can you get your nose to the charging handle?
 
#6
The truth is we are all different. It seems odd, but perhaps your facial structure combined with your technique makes you feel as though it’s too high. I’m guessing this is in the prone that you notice it, but in more dynamic shooting situations or with irons don’t even notice.

While it is true for true precision shooting that you don’t want to have to strain your neck; you should relax behind the rifle. I find with ARs personally I like to hold my head straight up and down and rarely rest my cheek on the stock as I would on a bolt action. I run 1.93” for my LPVOs and 1.54” for my “precision” optics, such as the Mark 6 3-18x on the AR. I don’t “sink in” like I do on a bolt gun.

A solution for you, since it sounds like you use a pig of a rifle with an NXS on top would be a Magpul PRS stock. That would allow you to run the charge handle and still adjust the gun for you. However if your current setup works for you and there on no problems being created, then do not worry about it being unconventional.

Where are you located?




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#7
General rule:

1.375" for using a lot of prone use
1.54" for general optic use (LPVO/DMR)
1.93" for head's-up use or to clear IR/accessories (not ideal for prone)
2.04" similar to 1.93" but if you use clip on NV, you can use a .5" riser to line it up with your optic

Given your problems, noted, I think more of your problem is with your fit of the rifle stock. If you happen to be like my spotter/partner has magnificently high cheekbones and has to build up his cheek piece so much so that normal people cant get behind his optic. If you look at precision rifle shooters, you will note now how completely adjustable stocks are...and for good reason. Getting the gun to fit you is very important...it may mean ditching the A2 stock. Not sure of your stature, but I run an AI bolt gun at full buttstock extension...I'm over 6'5" and I still think the M16A2 is a bit long/uncomfortable for my liking in the prone.
 
#8
pointblank4445 has an excellent point I was going to come here to add: It depends. The usual line is "as low as possible" but you DO want higher for standing up, and even higher to make sure you are lining up with clipons, etc.

Also: even higher for using a NOD. You can use an RDS (or if really cool, an LPVO) as a zero emissions night aiming scheme by flopping the monocular to the right (or agin: if very cool, having a BNVD) and getting it behind the optic. This is easier with higher ones and some folks who do that for a living specifically get high mounts.

I also agree entirely that you don't just have to move the scope, but can move the stock. I run the CTR on (almost) all my guns, including my precision rifle. It has a clipon-height scope, so you cannot get on easily without raising the stock. But, they make nice risers, so I just got a couple, use the one that's the right height for ME, in all likely positions. I have done the same in previous iterations of my ARs, to make sure I never float my head over the stock, but always have that third point of contact.
 
#9
Thanks to all for the thoughtful responses. Thanks as well for the vote of confidence in my obscure set up.

Over the holiday, I was able to get behind a friends rifle with a very similar set up, but his unmount has 1.375 rise. I definitely had to float up off his stock to get a good picture. I felt like I had my jaw on the butt. As Pointblank4445 noted with his partner, my friend cannot even use my rifle. I'm 6'1" and have to agree the A2 LOP feels long/uncomfortable.

While I do indeed have a pig of a rifle, I do like to drag it around the woods and as contradictory as it may be to my precision shooting goals, the PRS stock doesn't appeal to me. Maybe I'll have to warm up to the idea. I looked into the CTR, but it's my understanding that they interfere with the charging handle. I'm thinking I may simply stick a small pad on my existing set up.

Finally, to answer a question, I live in central Oregon.
 
#10
Thanks to all for the thoughtful responses. Thanks as well for the vote of confidence in my obscure set up.

Over the holiday, I was able to get behind a friends rifle with a very similar set up, but his unmount has 1.375 rise. I definitely had to float up off his stock to get a good picture. I felt like I had my jaw on the butt. As Pointblank4445 noted with his partner, my friend cannot even use my rifle. I'm 6'1" and have to agree the A2 LOP feels long/uncomfortable.

While I do indeed have a pig of a rifle, I do like to drag it around the woods and as contradictory as it may be to my precision shooting goals, the PRS stock doesn't appeal to me. Maybe I'll have to warm up to the idea. I looked into the CTR, but it's my understanding that they interfere with the charging handle. I'm thinking I may simply stick a small pad on my existing set up.

Finally, to answer a question, I live in central Oregon.
LaRue makes a riser that reciprocates with the charge handle.


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#11
LaRue makes a riser that reciprocates with the charge handle.


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Or you've got the SAPR that goes on a SOPMOD stock that adjustes LOP and has a riser that swings out of the way if you don't need it. Hopefully they're still a thing.

Frankly, @Daniel L...one of those or just goe all-in and do the Magpul PRS stock.