Help on understanding RING heights.

[jg0001]

So, I plan to buy a fancy schmancy scope to be used on my AR-15 platform rifles.

Assuming I am mounting this scope on an utterly flat rail, how do I go about figuring the lowest ring height I will need? I never see any mention of actual SIZE other than interior diameter. Are "Low/Med/High/ExtraHigh" common designations with similar heights across brands?

For my test case, assume a 30mm tube and a 50mm bell (again, on a totally flat rail). Would that be "medium" height to clear the rails and perhaps high or extra high to put it in co-witness levels? I really don't want to have to buy multiple heights, especially if I opt for the premium rings which are far from cheap.

I always thought the rule was to generally try and stay as close to the bore as possible, but I see a lot of pictures where the scope seems far higher than it would need to be (with no mention of it being that way due to distance shots).

Thanks in advance.

 

[uncyboo]

Are "Low/Med/High/ExtraHigh" common designations with similar heights across brands?

No. Lo/Med/Hi/ is different for each maker in my experience. Most of the maker's website have a tech section to give you either...

1) Distance from the base to the bottom of the ring, or...
2) Distance from the base to the center of the ring...

 

[Scorch]

Two things to consider when scoping an AR:
* Ring height needs to be sufficient to not only clear the flat top, but also must align the scope with your eye, so you either need a riser or you need very tall rings.
* If you choose very tall rings, you need to make sure they are sturdy enough to take the beating from hanging way out there.

I typically recommend a riser (you can choose the rings you want in order to properly align the scope to your eye) or a dedicated AR scope mount base.

Dedicated base
http://www.midwayusa.com/viewProduct/?productNumber=141657

Riser
http://www.midwayusa.com/viewProduct/?productNumber=878944

 

[jg0001]

Scorch... excellent stuff. I always love it when someone gives a link to an actual product -- that took any confusion out of the equation immediately.

To put it simply, you don't think anything short of High or Very High rings are a 'do', assuming I didn't use a riser or base of any kind. Though, seeing the one piece setup with integral rings is attractive to me, especially since I've thought about using this scope on 2 different rifles (both AR setups).

If I may ask...when you say...

* Ring height needs to be sufficient to not only clear the flat top, but also must align the scope with your eye, so you either need a riser or you need very tall rings.

...is there any reason to believe the centerline of the scope would need to be higher than where the iron sights would otherwise place my eye? (again, don't assume very long range applications)

 

[TRguy]

Not my words but use them often, from sniper's hide

There is a systematic way of calculating ring height that doesn't require more than a simple elementary school ruler. You measure 3 things:
1. the height of the front of your base/rail from the barrel
2. the height of your rings from the top of the rail to centerline
3. the outside diameter of the bell of the scope (not the size of the objective lens)

Here is the equation:
[rail height + ring height] - [bell diameter x 0.5]
If the value is positive, then your bell will clear the barrel. Optimally, you want that bell to be about 1/4" or less over the barrel. This will give you a tight cheek weld and provide for more precise trajectory. Be sure to account for Butler Creek caps if you intend on using them.

If you are using a 40mm objective, then you can use the lowest rings and bases available, as the bell will certainly clear the barrel with no problem. i.e. don't worry if the bell ends up being higher than 1/4" over the barrel.

http://www.youtube.com/watch?v=gpLi064e_JI

 

[socom58]

I have a Burris PEPR mount on one of my ARs (the one that Scorch linked to) and it has worked very well in combination with a Nikon 2.5-10. This mount also skews the scope far enough forward as to maintain proper eye relief on the AR platform

 

[CPTMurdoc30]

I used Burris extreme Tactical Rings 1" high first then found that it was to high for me. I then switched to the 3/4" rings and prefer these much better.

I like to mount my scope as low as I can so to ensure a good cheek weld with stock.

 

[Niner4Tango]

Already lots of good advice, but here is a twist on it.

The height of your scope should be the one that gives you the correct cheek-weld. A mil-spec (FSB marked "F") removable carry handle puts the aperture at 36mm above the top of the picatinny rail. This is a nominal 1.5". So, assuming this is the "mil-spec cheek-weld" height, and also to co-witness, you want the center of the scope at 1.5" above the top of the rail.

That means dimension A should be 1" for a 25mm tube: http://www.burrisoptics.com/arpepr.html

The PEPR like mentioned above, gives you that scope height. Another, the one I use, is Warne Maxima Flat Top rings: http://www.warnescopemounts.com/maxima_rings.html

What scope are you getting? There are so many choices....

 

[LanceOregon]

So, I plan to buy a fancy schmancy scope to be used on my AR-15 platform rifles.

That would typically be a very bad idea to do, unless this is a long heavy barrel model meant only for target shooting or varmint hunting.

.

 

[jg0001]

I'm leaning towards a Bushnell Elite 6500 Tactical that is 4.5-30x & 50mm bell. On indoor ranges, even short ones, I commonly use a 4-6x mag just fine. Whether I'll ever see the upper end of the scope's mag range, I don't know. I know it is a bit ridiculous (& expensive -- I'll be cashing in credit card points for Cabela's gift cards), but I figured it's a nice offset to my Eotech XPS3-0 I use now on the one rifle. I don't expect to be shooting anything close to 500yds+ anytime soon, at least not out of my current rifles, but I would like to have that option on a future rifle. If this ends up being too much scope for my ARs, it'll just prod me to get a bolt action rifle at last (I keep getting close, but end up buying something else).

[I should say, I don't care about co-witnessing, so the standard sights on each rifle would either be folded down or removed.]

 

[Scorch]

If I may ask...when you say...

Quote:
* Ring height needs to be sufficient to not only clear the flat top, but also must align the scope with your eye, so you either need a riser or you need very tall rings.

...is there any reason to believe the centerline of the scope would need to be higher than where the iron sights would otherwise place my eye? (again, don't assume very long range applications)

The centerline of the scope needs to be pretty much exactly where the irons are. Most scope rings won't get you there, they are designed for rifles where the line of the stock is lower than the receiver by 1/2"-3/4", not in a straight line with the top of the receiver. So you need to compensate for the lack of drop on the AR by using slightly higher rings.

 

[Omaha-BeenGlockin]

Since there is no stock drop in an AR you need very high rings that put the scope 1'' to 1.5''in over the rail--just to see through the thing.

With rings that high--the size of the scope usually doesn't matter.

 

[jg0001]

Just placed my first order with www.cgwgun.com -- I ended up getting:
SKU Item Shipping Price Qty Total

BSN-654305T Bushnell Elite 6500 Tactical Riflescope 4.5-30x50SF Mil Dot
$785.50

BUR410341 Burris P.E.R.P Tactical Scope Mount 30mm $72.99

I haven't used cgwgun.com before, but their site was reasonably impressive, the person I spoke to on the phone (to get a sense they existed & a feel for how they treat customers) was very helpful, and their price on the scope itself was incredibly good.

While I planned to buy from Cabela's, their price was just awful. So the rest of you can benefit from my experience, here's where the big boys fell out:

Bushnell Tactical Elite 6500 4.5-30x50mm Riflescope (MilDot Reticle)
Official Model # = 654305T
http://bushnell.com/products/scopes/riflescopes/elite6500/654305T/


$949+$20 shipping
http://www.cabelas.com/cabelas/en/t...abelas/en/common/search/search-box.jsp.form23

$899 (with $50 off, pre 10% discount if you post a review on their website of any prior purchase)
http://www.opticsplanet.net/bushnell-elite-6500-4-5-30x50-riflescope.html

$849 free shipping
http://www.amazon.com/Bushnell-Tactical-Elite-4-5-30x50mm-Riflescope/dp/B001MYIP14

$825.48 free shipping -- totally odd that Amazon had TWO different prices, both showing as sold by Amazon -- I have heard of this before, but never saw it so dramatically
http://www.amazon.com/Bushnell-Tact...=UTF8&s=sporting-goods&qid=1274328818&sr=1-16

$785.50 free shipping (from Nevada)
http://www.cgwgun.com/Rifle-Scopes/Bushnell-Elite-6500-RifleScope__BSN-654305T.aspx

Also worth noting is that OpticsPlanet.com markets itself as a variety of websites. The same scope choices & prices show up under
http://www.tactical-store.com/ts-bu-rs-elite653050.html
I did call them to confirm they are the same as opticsplanet.com What was interesting is that on the www.tactical-store.com site, they have a link on the product page to request a price match (I didn't try it, but it's nice to know it is there). However, they were missing a $50 coupon code that opticsplanet had. On opticsplanet, instead of having a price match link, they have a "best deal guaranty" link which suggests you can call them up to 24 hours after purchase to ask them to match a price.

Thank you to everyone for your help & guidance in this process. I'm eager to try this out on both of my AR's -- one just a measly S&W M&P 15-22, the other an LWRC M6A3 in 6.8 SPC. Like I said before, if this is too much scope for those (it's definitely ridiculous on the 22, but that's the one I shoot 300rds each trip to the range), I'm not worried as I seem to be getting a new rifle or two every year.

 

[rbernie]

FYI - the Leupold Rifleman 'Weaver see-thru' rings are the PERFECT height for mounting 1" tube optics onto an AR15 flattop. They are also less than $20, and I've used them on my hunting ARs for years. They've survived the knocks and drops of hunting use quite well.

 

[jg0001]

Received the scope & rings/platform (PEPR) yesterday. Excellent stuff. It is a lot of scope for a little 22LR rifle (what I have it on now), but it should be a ton of fun. Set to 4.5x mag, I can finely focus on objects as close as 10-15 feet (I didn't try shorter distances). I have yet to take it outside to try it at anything close to the 30x max magnification. With the AR P.E.P.R. (30mm), the bell still has about 1/2 an inch of clearance from the rail. In the grand scheme of things, not too bad.

 

[SmokyBaer]

A good scope cap from Butler Creek will take up a little of that 1/2" gap.

 

[jg0001]

Are you referring to flip open caps? Who sells good looking ones? The aesthetics of the scope are so good right now, I'd hate to ruin it.

 

[CPTMurdoc30]

I had 1" tall SWFA Extreme tactical rings for my flattop AR and found it to be to high even with my fat face. I swapped a buddy for 3/4" rings and it works much better for me. You have to try them and see if they are going to work for you.

I would go to a gun store and see if you could try 3/4" 1" and 1.5" tall rings. See which ones fit you good then get them.