Rifle scope elevation problems


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Warsaw Wizard
September 11, 2010, 04:11 PM
I mounted a 10-40x60 tactical scope on my heavy bbl national match M1A. I used a Mil Spec. side mount with intrical rail and low mount rings. I leveled the rifle in all directions, made sure the mount was properly aligned, level, and parrellel to the bbl and receiver. The scope is level and parrellel to the rifle and bbl. My bore sight is exactly aligned with my "iron sight' picture. I have 4 inches of windage from both sides of center at 12 feet. (The max distance of my shop.) My problem is that when I align the reticle in the scope to the bore sight I only have 2 inches of elevation left. That equates to 2 inches above the target and 6 inches below the target. Any suggestions on how to correct this problem? Or let me know if it really isn't a problem and I'm just over thinking it. If it is a problem I would like to correct it before I go the the range.

Thanks for any thoughts and help,
The Warsaw Wizard

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Derek Zeanah
September 11, 2010, 04:17 PM
Tech support is more a place for help with the board software itself, though I can see why you thought this was the right place to post this. Moving it for you...

paperwork351
September 11, 2010, 10:51 PM
I'll be watching this thread because I have the same problem. At 20 feet I am 12-15 moa low and have run out of upward adjustment. I thinking that increasing the distance might solve the problem (50-75 feet) but going outside would freak out the neighbors. I have no experience in mounting scopes but I think it takes more clicks at a shorter distance to raise one inch than 4 clicks at 100 yards. Right now I am unable to travel to a range to test.

esheato
September 11, 2010, 11:09 PM
What you should be doing is a boresight. A very rudimentary alignment of bore and crosshairs. There are numerous devices available to assist with this procedure. If this is your first time, call your gun buddy who has done it and have him show you how. Or pay a smith and ask to watch him do it.

From there, you take your boresighted rifle TO THE RANGE (!!!) and see where it hits at 25 yards to start. Work your way out to 100 to get your baseline zero.

There's no shortcut to this...you have to shoot, adjust, shoot, adjust. Shouldn't go through more than 5-10 rounds to do this if your boresight is decent to begin with.

PT1911
September 11, 2010, 11:13 PM
the problem is you are using a 60mm scope and trying to set it at 12 feet.. not going to work out... you are overcoming a HUGE distance between the bore and crosshairs in under 5 yards.. your best bet is to get a bore sighting device or just go to the range.

Imagine the "arc" of the bullets trajectory as it comes out of the barrel.. it must actually rise up to the straight line of sight that is the scope's crosshairs. This cannot be done in such a short distance. This is also why, though a high mounted scope can be used to shoot accurately farther than one mounted close to the bore, the higher the scope is from the bore, the farther off you will be at ranges other than your set zero.

stretch it out to 50,75, or 100 yards before you freak out.

paperwork351
September 12, 2010, 12:24 AM
The boresight I used was a Sightmark laser. What PT1911 said about the correction at such a short distance is what is happening with me and what esheato is correct about the range procedure.

DRYHUMOR
September 12, 2010, 06:02 AM
I've found that the 25 yd zero works out to be a bit high at 100 yds, and maybe a couple of inches left or right, depending. Whether a bore sighter or looking through the barrel of a bolt gun. It's a good way to get you close to where you need to be. On the paper so to speak.

Best thing to do after that, is have a large backboard for the target, shoot it at 100 yds and work it in to the zero you need to have.

Plus, it's good practice.

rcmodel
September 12, 2010, 11:58 AM
Bore-site it about 2 1/4" low at 12 feet, (X-hairs 2.25" above the bore line) then shoot it at 25 yards to confirm you are on paper.

Then shoot it at 100 yards to fine-tune it.

Here is an Eotech 10 meter bore sight target to help you get the picture.
http://www.eotech-inc.com/documents/M16A4-M4MWS_EOTech_LBS_Target.pdf

rc

LaserSpot
September 12, 2010, 10:57 PM
Bore-site it about 2 1/4" low at 12 feet, (X-hairs 2.25" above the bore line) then shoot it at 25 yards to confirm you are on paper.That's only for an AR with EoTech sight.


Your best bet is to bore sight at 25 yards, then shoot at 25 yards. Dead-on at this range will usually be on paper at 100. Use a ballistic calculator to see exactly where your load should hit at 25 yards for a long range zero.

http://www.biggameinfo.com/BalCalc.aspx
http://www.handloads.com/calc/

esheato
September 12, 2010, 11:46 PM
See? Everyone has their own way of doing it.

Bottom line: get to the range and work out the kinks. I bet you'll find they weren't that big of a deal.

rcmodel
September 13, 2010, 11:07 AM
That's only for an AR with EoTech sight.It has absolutely nothing at all to do with whether its an EoTech, or a scope, or an AR-15.

If the center line of the optic is 2 1/2" above the bore line, the rifle will be shooting about 2 1/4" low at 12 feet when it is in 200 yard zero, regardless of the type of optic used.

With the OP's 60mm objective lens scope on an M1A, it may be higher then 2 1/2" above the bore line.

rc

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