THIS IS PROBABLY MORE INFO THAN YOU MIGHT WANT. I PULLED THIS FROM OUR INDUSTRY FORUMS PAGE:

ON THE AR' FAMILY OF WEAPONS, THERE ARE TWO CRITERIA REGARDING SCOPE MOUNTING THAT MUST BE TAKEN INTO CONSIDERATION FOR THE SCOPE TO BECOME AN EFFECTIVE PART OF THE SYSTEM:

1. HEIGHT ABOVE THE COMB

2. EYE RELIEF

THE IRON SIGHTS ARE 1.4" ON AXIS ABOVE THE AR-15/M-16/M-4 FLAT TOP UPPER RECEIVER. THIS TRANSLATES INTO THE AVERAGE HEIGHT ABOVE THE STOCK COMB FOR THE AVERAGE SHOOTER, AS ORIGINALLY ENVISIONED BY MR. STONER.

I HAVE SUCCESSFULLY USED SCOPE MOUNTING SYSTEMS AS LOW AS 1.25" ABOVE THE FLAT TOP AND AS HIGH AS 1.6" ABOVE THE FLAT TOP.

EYE RELIEF IS A FUNCTION OF THE SCOPE'S DESIGN. MOST HIGH QUALITY SCOPES ARE DESIGNED TO BE USED ON BIGGER CALIBERS THAN THE 5.56MM, NECESSITATING AN EYE RELIEF IN THE 3.6" - 4.0" RANGE, TO PREVENT THE SCOPE FROM COMING INTO CONTACT WITH THE SHOOTER'S SNOT LOCKER UPON RECOIL.

THE PROBLEM THIS PRESENTS WITH THE AR-15/M-16/M-4 FAMILY OF WEAPONS IS THAT THE UPPER RECEIVER IS OFTEN NOT LONG ENOUGH TO MOUNT A SCOPE ONTO AND AT THE SAME TIME PROVIDE SUFFICIENT EYE RELIEF.

WHAT TO DO?

MOUNT A SCOPE APPROX 1.4" ON AXIS ABOVE THE FLAT TOP UPPER. USE A STOCK LONG ENOUGH TO GIVE SUFFICIENT EYE RELIEF. HERE'S AN ACCURIZED 14.5" M4A1 WITH A LEUPOLD LRM3 MOUNTED 1.4" ON AXIS ABOVE THE RECEIVER, AS FAR FORWARD AS POSSIBLE, WITH THE CRANE STOCK PULLED OUT BEYOND A2 LENGTH:



MOUNT THE SCOPE ON A CONTINUOUS OR EXTENDED RAIL THAT WILL ALLOW ONE TO MOUNT A SCOPE FAR ENOUGH FORWARD TO PROVIDE EYE RELIEF.

AN EXAMPLE OF THIS IS THE LEWIS MACHINE & TOOL MRP, USING BADGER 1.40" ALLOY RINGS:





HERE IS ANOTHER EXAMPLE, ON A CLONE OF THE EARLY VERSION OF THE SPR, USING AN ARMS SPR RAIL AND ARMS #22 MEDIUM RINGS, PUTTING THE AXIS OF THE SCOPE 1.6" ABOVE THE FLAT TOP UPPER:



THIS CAN ALSO BE ACCOMPLISHED WITH THE ARMS #35 QD BASE WITH #35 MEDIUM TRACK LOCK RINGS:



YET ANOTHER WAY TO ACHIEVE THIS IS TO USE THE ARMS #36-EX BASE WITH RINGS OF CORRECT HEIGHT. SEE THE TOP WEAPON:




PERHAPS THE MOST ELEGANT SOLUTION IS A SCOPE ESPECIALLY DESIGNED FOR THE LOW RECOILING 5.56MM WITH A SHORTER THAN NORMAL EYE RELIEF, LIKE THIS LEUPOLD TS-30A2 ON AN SPR MK 12 MOD 1 CLONE, MADE OF UNOBTANIUM, IN ARMS #22 HIGH RINGS:



BUT, IF YOU MUST USE A SCOPE WITH AN EYE RELIEF SUITABLE FOR HEAVY CALIBER WEAPONS, AS MOST HIGH QUALITY ONES ARE, THE NEWEST ALTERNATIVE IS THE LARUE TACTICAL TWIN THROW LEVER CANTILEVER MOUNT & RINGS:



THIS MOUNT PLACES THE SCOPE AT 1.5" ON AXIS IF USING A 30MM SCOPE, AND 1.41" IF USING A 1" TUBE. THIS IS WHAT M.S.T.N. NOW USES FOR THE NIGHTFORCE "TEST MULE" SCOPE WE USE TO BREAK IN OUR PRECISION UPPERS. AT A MERE SEVEN OUNCES, THIS IS AN AMAZING COMBINATION OF VERSATILTY AND STRENGTH AT A SURPRISINGLY LIGHT WEIGHT.

ALL WE USE IS LARUE ON ALL OPTICS, PRESENTLY.

WES GRANT
M.S.T.N.

NO PROBLEM.

ALL THIS INFO AND MORE LIVES ON OUR INDUSTRY FORUM.

ar15.com/forums/forum.html?b=2&f=134

WES GRANT
M.S.T.N.