Updated 11-25-14 (see new reply)
Equipment: 460XVR 8&3/8bbl w/ Nikon 2-8x EER SCOPE mounted on Weigand rail and Warne rings x2
Sequence of events:
Range session #1
• sighted in 25yd with commercial Hornady 200gr
• sighted 50yd w/Hornady comm 200gr
These rounds grouped around 1-1.5in.
• "Attempted" to sight in @50yd with handloads (300gr Hornady XTP MAG over IMR 4227 36,37,38,39gr in once fired Hornady brass COL 2.160 x 5rds each)
These grouped well but 8" and I was out of downward elevation adjustment!!!!
So, I go home and remove scope and remount, switching the rings front to back, back to front and bore sight it.

Range Session #2
• sight in at 25yd w/Hornady comm 200gr, groups well.
•"Attempt" to sight in handloads (same load as above except 38gr and COL 2.178) at 25yd
These grouped well, but 4.5" high (note this at 25yd)!!! One again, this is with using all available downward elevation adjustment!

The only fix I can think of is to shim up the front end of scope.
Any other observations, suggestions. I really need help guys; I am wanting to hunt with this thing this year. Thanks for your time.

Swapping the rings front-to-back was the right move and exactly what I'd of tried. With hunting season fast approaching, I'd probably shim with some aluminum shims cut from a pop can, just to get a good zero. Then figure it out later. Maybe some Burris Signature Zee Rings with the optional "offset" inserts would fix the problem.

http://www.brownells.com/optics-moun...prod57094.aspx

__________________
~ S&W aficionado in training ~

C'mon fellas. Where are the XFRAME EXPERTS? Have others had such a problem? If I do use soda can tin as a shim, is one strip thickness usually sufficient or does it take multiple strips?
Thanks,
L.P.

I bore sighted mine and zeroed at 100 yrds. Groups were about three inches not to bad with a revolver and they stayed at about that plus or minus an inch at 200 yrds. But never tried at 25 yrds. I use the leupold vx3 handgun scope and leupold rings and haven't had any problems. Sorry I know it's not much of a help. Oh and I only used hornady loads.

What range are you trying to get zero at? Do you have sufficient information about the handload, e.g., ballistic coefficient and muzzle velocity to calculate trajectory?

I calculated the trajectory for the commercial Hornady 200 grain (BC 0.151 and muzzle velocity for 8.75 inch barrel at 2200 fps). Assuming sight elevation of 2 inches and +4.5 inches at 25 yards, distant zero is 350 yards. Maximum elevation is about 28 inches at around 150 yards.

My 460 Performance Center has a longer barrel (higher muzzle velocity) and built-in rail (no shim). I wanted a nearer zero so I use Burris Signature Zee rings which give a wide range of adjustments, as Kernel Crittenden suggested above as an option. Also better to have the scope positioned near the middle of the range rather than striving just for the edge of elevation adjustment.

I would make two suggestions.

1) Skip your hand loads for this year, 8 inch groups at 50 yards won't cut it and you face too much risk of a "foul" shot deer you have to chase down. Seriously, you can expect your group sizes to just about double using an improvised rest versus a shooting bench. In addition I use a group size of 4 inches to set my maximum distance, which means your maximum distance is a bit under 20 yards.

2) By using commercial ammunition your sighting issues are solved, because you didn't report any issues zeroing the 200 grain Hornady load. As for a question on whether a 200 grain bullet will stop a deer, think about that for a minute. People have been taking deer with 357 Magnum handgun loads since 1935 using 158 grain bullets, so a 200 grain 45 caliber will most certainly do the job as long as you do yours and hit well.

I agree with scooter. Had a similar problem with my 480 Ruger. I now use factory for hunting and my loads for dinking around. If factory works don't fix it. It ain't broke. IMHO

Except I don't use a scope. However, the heavier loads were hitting way high.

First you have to understand why they are hitting high (I did not at first)

After much conferring with other shooters we determined the heavier rounds were staying in the barrel longer. So, muzzle rise could account for the change in POA.

My fix was simple. When taking a grip on the gun I raised my hand position as high as it could go (a full 3/4") then using the intertlocked thumbs grip I really concentrated on a strong enough grip to reduce muzzle rise. That and a high grip translated the recoil more back than up and the difference between heavy and light rounds was reduced significantly.

Zero your scope at 100 yards with the Factory FTX.

I shoot a 240 grain XTP on top of H110. Very accurate at 100 yards.

Thanks for replies. Note, "1) Skip your hand loads for this year, 8 inch groups at 50 yards..." I may have been unclear in original post. Clarification: I have a pretty good grouping at 50yd (~1.5"); the problem is that the group is 8" high. I understand that heavier bullets often impact higher than lighter, but this seems somewhat extreme. And I am surprised that my scope is not capable of adjusting for this 300gr projectile.

After your clarification I now understand your problem. I have this particular scope and Nikon states that the range of adjustment is 40 MOA. Unfortunately they aren't exactly clear on whether that is 40 MOA total or +/- 40 MOA. From the sound of it it's likely 40 MOA total and your shift is equal to 16 MOA, so if the scope was perfectly centered with a 200 grain bullet you would be 16 clicks from the maximum with your 300 grain load. I suspect that you are using part of the adjustment range getting the 200 grain load zeroed and you just don't have enough remaining adjustment to zero for the heavier bullet. So, your only choice is to add a bit of shim to the front mount.

So, making a couple of assumptions leads to the following conclusion. 1) You have your scope rings mounted 3.5 inches apart center to center. 2) You need to add enough shim to shift the POI by 18 MOA, or 0.3 degrees. The using these 2 assumption leads to the equation that Shim Thickness will equal (the Tangent of 0.3 degrees) times (3.50 inches). Doing the math indicates that a shim 0.018 inch thick under the front mount will result in a shift that will allow you to zero your scope with either the 200 grain commercial load or your 300 grain handload.

I think I figured it out.... Coriolis effect.

Forget that. Go with what scooter said.

If a pop can averages about 0.0042'' thick, you'll need three, maybe four, shims.

__________________
~ S&W aficionado in training ~

Update:
I used a piece of feeler gauge .018 thick to shim the front portion of scope rail and was able to zero my reloads (300gr XTP MAG over IMR 4227 39.0gr) at 50 yds. I still need a lot of practice to be more consistent.

Nobody will argue that your groups wont be sufficient. And if by chance the animal still bolts away the blood trail would be hard to miss.
Remeber to log your scope zeroes in case you switch ammo and post your trophies!