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Posted: 4/7/2006 5:50:26 PM EDT
[Last Edit: 4/7/2006 6:41:39 PM EDT by mikko]
Okay I have a question regarding two rigs posted within the last two pages of the pic thread.
pages 38 & 39 currently

It is about the AR's that have big scopes mounted back on the upper receivers. Krill-p's and the photo that 03USMC11 posted are prime examples of my question.

First, if their scopes are anything like mine then I think there is NO WAY the placement of the scopes allows enough eye relief for proper head placement and cheek weld. i.e. nose to charging handle.

If I'm wrong let me know why I'm mistaken or please explain why I see so many rifles with the scope mounted far back on just the upper receiver. Especially when they have a railed forend???

Why the hell spend the money on a railed fore end when you're not going to use it for an optic mounting platform? Is it a loss of zero issue? I don't understand all the rifles outfitted with railed forends when at most you'll mount a VFG or maybe a light. There are much cheaper ways to do both of those items than a railed forend.

Here is my BM Varminter. This is a project gun mostly because the scope has no where near enough eye relief in the configuration pictured.

The gun shot fine with the adjustable carbine stock attached and I really did like how the adjustable stock allowed me to choke up on the gun and bring the wieght closer to my body but it has been taken off and replaced with a regular rifle stock.

I'd like to either get an ARMS # 38 super extended 14" swan sleeve and mount the scope on that or get a continuous railed foreend like a Troy and mount the scope further forward. I'd probably also look at getting a Bushmaster solid shorty stock to shorten the LOP.

What is you's guy's input?

Link Posted: 4/7/2006 6:07:44 PM EDT
i can't tell which scope you're using or how much eye relief you need, but it appears to be >10x with 1" scope body...using a LaRue SPR/M4 QD mount, my Nikon 2 1/2x10 mounts at the front of the upper receiver rail and the end of the scope eye piece aligns with the back of the charging handle..this provides excellent eye relief for my setup and the collapsible stock is in the next to the end notch...other LaRue products provide more eye relief, maybe check out SPR-E to see how much more eye relief it provides
Link Posted: 4/7/2006 6:09:46 PM EDT
Fore end rails are not good for mounting optics, especially scopes. The rails probably won't line up perfecly with the flat top.

You need to move the scope about 3-4" forward of the charging handle. Similar to the position on the iron sight placement but farther forward.

White Oak sells an extended riser that will give you the inches you need to mount the scope farther forward and have a forward check weld (as in shooting irons). You might need to elevate the stock (add on or improvised cheek rest) for correct eye alignment.

But what the hell do I know, I shoot irons.
Link Posted: 4/7/2006 6:18:12 PM EDT
Yeah its not a great picture.

My scope is a Leupold Vari X-II 6-18 x 40mm AO Target Scope:

Actual Magnification: 3.6(3.5X) 13.8(14X)
Length (in): 13.5
Eyepiece Length (in): 3.0
Objective Length (in): 3.8
Objective Diameter (in): 2.3
Eyepiece Diameter (in): 1.6
Tube Diameter: 30mm
Weight: 19.5 oz. / 553 grams
Eye Relief (in): 4.5(3.5X) 3.8(14X)
Eye Relief (mm): 114(3.5X) 97(14X)
Obj. Lens Diameter: 2.0in / 50mm
Max. Adjustment @ 100 yds (in): 60
Max. Adjustment @ 100 m (cm): 166.7
FOV @ 100 yds (ft): 27.2(3.5X) 7.1(14X)
FOV @ 100 m (m): 9.1(3.5X) 2.4(14X)
Ring Spacing
Max. Mount Ring Spacing (in): 6.5
Front Ring Space (in): 2.7
Rear Ring Space (in): 2.6

Features of Leupold Vari X II 6 - 18x40mm Adj. Obj. Target Scope:

* Outstanding optical quality
* Multicoat 4 lens system
* 1/4 MOA click, target-style, windage and elevation dials
* Leupold Full Lifetime Guarantee
Link Posted: 4/7/2006 6:53:06 PM EDT
[Last Edit: 4/8/2006 5:12:39 PM EDT by IL_Shooter]
mikko...those specs helped identify some things
1. eye relief on my scope is 3.39" and yours is 3.8" -4.5"..my SPR/M4 mount is maxed as forward as it can go..only LaRue option would be SPR-E, but i'm not sure how much more eye relief you would get.. 1/2" ? i don't know of any other 'cantilevered' scope mounts that provide more eye relief
2. outside objective diameter on mine is 53.5 mm (lense is 44 mm) and on yours is 2.3"~58.4mm (lense is 50 mm)...from your picture it appears there is adequate clearance for the objective...on my setup i had to remove the flip up BUIS because of lack of vertical clearance
3. double check how scope mount fits onto your scope...draw a full size receiver/handguard picture to scale, diito LaRue scope mount picture to scale and overlay scope body picture with detailed measurements of scope body lengths, elev/wind turret length as well as overall length of eye piece/objective full size tube including tapers...adjust these pictures for maximum eye relief and check result
if you can't get enough eye relief using this method, then consider 'bolt on' pic rail extender for upper receiver, such as, Badger AR Riser Rail P/N 249-25...maintaining height above bore might require new individual scope rings
YMMV
Link Posted: 4/7/2006 7:01:26 PM EDT
I have the railed forend so I can add and remove my bi-pod, my flashlight and my Tango Down Vert grip. Not all situations call for all 3 and I can add and remove as I need! I have no problem with eye relief at all. I do not shoot nose to charging handle when using a scope, only with Irons. I set my adjustable stock 4 positions to the rear in the summer and 2-3 to the rear when hunting in the winter.




This is how it was before the rail. No way to add my VFG or flashlight and the bipod was a hassel to add and remove.

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