How low should you go?

redbobfire · Jan 22, 2014

I have a 6.5x20/50 Zeiss that I will be mounting on a RRA 3 uppper. What is the best distance above the barrell to mount this? Is there a set of rings that you would recommend for this appication. I will be shooting this rifle at both Prairie dogs (10 yards to 200 yards ) and Coyotes out to 300 or so.

Nwcid · Jan 22, 2014

As low as possible is always best.

Member 34319 · Jan 22, 2014

Nwcid said:
As low as possible is always best.

That is not always easy to do with ARs.

I built an upper for longer ranges using a slick sided DPMS riser upper receiver. I use low rings.

My pops built his using a standard flat top. He uses a Rock River Arms one piece mount as high rings did not clear the rail.

My wife's, I was able to squeeze the scope in on the flat top using a set of warne high rings.

I would take it in to a shop if your not sure and test out different set ups. ARs don't get the luxury of having the glass super close to the bore line, but you still want it to be close.

Oh and maybe get a set of those angled/offset irons of your thinking of getting off a shot at less than 50 yards. If not your going to shot low all the time. I'm sighted in at 200 yards. My scope line is probably 1.5 inches above my bore line. I'm roughly 2" low at 50 yards.

PORSCHE928S4 · Jan 22, 2014

DNZ Freedom Reaper mounts for the AR

BillM · Jan 22, 2014

I've got a 16x SuperSniper scope on a flat-top AR. It has a large diameter free float
forearm, and high rings. Bell clears by about .250". Centerline of the scope to bore
centerline is 2.555".

Different gun---my 3 gun AR---Millet DMS 1x-4x in a Larue SPR-E mount.
Scope centerline to bore centerline 2.731". Wouldn't want it any lower, with
my fat cheeks another 1/4" higher would be nice.

Nwcid · Jan 22, 2014

Reno911 said:
That is not always easy to do with ARs.

I built an upper for longer ranges using a slick sided DPMS riser upper receiver. I use low rings.

It may be hard to go low, but it is extremely easy to go as low as possible. It is IMPOSSIBLE to go any lower........

My pops built his using a standard flat top. He uses a Rock River Arms one piece mount as high rings did not clear the rail.

My wife's, I was able to squeeze the scope in on the flat top using a set of warne high rings.

I would take it in to a shop if your not sure and test out different set ups. ARs don't get the luxury of having the glass super close to the bore line, but you still want it to be close.

Oh and maybe get a set of those angled/offset irons of your thinking of getting off a shot at less than 50 yards. If not your going to shot low all the time. I'm sighted in at 200 yards. My scope line is probably 1.5 inches above my bore line. I'm roughly 2" low at 50 yards.

I am a fan of the GG&G Scout rail, AR-15 Rail Scope Mount - Standard & Scout Rail Mounting System for M16 & AR15 Rifles Gives a solid base to us with "standard" height rings. has a long enough rail for use with longer scopes yet it not too long to cause problems with the objective end.

Spitpatch · Jan 24, 2014

Since the scope has already been decided upon (including a very marginally beneficial 50mm objective), getting the eyepiece down where it should be for natural and comfortable acquisition with proper cheek-weld for correct shooting form (an accuracy technique that is too frequently overlooked) becomes problematic.

A raised comb attachment might be advantageous for this choice of optics. Ergonomics figure in here as well, as a "fat-cheeked" shooter may do better with a slightly higher scope than a "skinny-cheeked" shooter (referring to the cheeks on the north side of our bodies, gentlemen).

As low as possible (and naturally comfortable) is always best.

redbobfire · Jan 24, 2014

Spit
I have found that at my age/vision the increased light and wider field of view with the 50 is beneficial. Thank you all for your time and advise.
B

erudne · Jan 24, 2014

I use riser blocks + high rings on my flat-tops, they are available in several heights, cost as little as $10

erslll · Jan 25, 2014

I am a fan of one piece mounts for ARs like the LaRue, Borbo or ADM. They are not the lowest option but they do seem to be the correct height for an AR.

jluck · Jan 25, 2014

A 6.5-20x50 might be a train wreck for working within 300 yards. Quick little critters will be hard to quickly acquire at ten yards with 6.5 power. I would rethink that optic and go with a smaller bell to aid in mounting at the same time. Maybe a 3-18x44 or similar, You'd still have PLENTY of magnification for vermin at 300 yards.

Nwcid · Jan 25, 2014

I guess I don't get why the big deal with the 50mm objective is. I have several and no problem.

Here is my Bushmaster Varminter with IOR 4-14x50mm (30 mm tube) scope. I am using the GG&G riser linked above with NF rings that if I recall correctly is the standard/medium height. As you can see the scope is at a great height for cheek weld and plenty of room for the objective. At the time I was engaging a target at 800 yards on a slight hillside.

I have a buddy that put a 50mm objective scope on one of his rifles and using just high or extra high rings it was still not high enough. He actually still had standard A2 hand guards and filed into them a bit to make the scope clear. As I originally stated you want the scope as low as you can for best performance. As others have stated one of the things you need to consider in the is the height it needs to be for a proper AND comfortable cheek weld. If the scope is not in the right spot for your eye naturally, it is not in the right spot.

To mount a scope the best thing to do is mount the scope where you think you need/want it. Close your eyes and mount the gun where it "feels right". When you open your eye the scope should be where you can see though it. If it is not in the right spot move the scope and try again.

Spitpatch · Jan 27, 2014

I avoided criticism of the choice of scopes by the OP (other than noting marginal benefit of the 50mm objective), because the choice was stated as a done deal, and he most probably had his reasons (to be respected).

"Marginal benefit" of a 50mm objective can actually become "significant" to some, as in the case of repeated and planned usage in very low light, or as a fellow "old fart" mentioned, waning eyesight.

But "marginal benefit" is not just a personal opinion. The very best evidence of this is the fact that Leupold was amongst the last (if not THE last) major optics manufacturer to get on that bandwagon. They KNEW the benefits were marginal (and spent a lot of effort attempting to educate the shooting public as to the science behind their evaluation). Finally, the market share was stampeding for "the latest greatest thing" and the "gadgets get the game crowd" was looking at other sources than Leupold. Leupold finally threw in the towel, in order to retain some market share.

They continue their education campaign showing specifics and science supporting their original reluctance to go with 50mm objectives.