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20 MOA RAIL & JBM Question

 
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  #1  
Old 08-28-2013, 07:36 PM
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Join Date: Dec 2009
Location: Redmond Or.
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20 MOA RAIL & JBM Question

Ok so a few of you probably saw my post in the Equipment section, but I'm having a heck of a time with my scope/20MOA rail.

Equipment info:
Semi Custom 300WSM 180 Accubonds @ 3100+FPS
Leupold VXIII Tactical 4.5-14x40 A/O
Leupold Custom Shop installed the Varmint hunter reticle
Leupold 20 MOA Rail
Leupold PRW medium rings

I zeroed my rifle @ 200 yds.
Checked at 607 yds with my 550 yd hold on top of target & was like 8 feet high! Woah! Adjusted scope way down. Shot 607 with my 550 yd hold on top of target & smacked it.
Ok, I thought, something is off. Ill shoot at 300yds. With my 300yd hold. So I did @ was almost 3 feet low!
So, re-zeroed my rifle at 300 with my 300yd hold. Moved out to 500 @ was way high again! Scratching my head, I tried my 400 yd hold on the 500 yd target & hit 5-1/2 inches low of dead center.

I chose the Varmint hunter reticle because it matches up so close to my 300WSM, & 300Wby shooting 180's at 3100 ish for the close stuff, & figured I'd dial anything farther.
It worked flawlessly on my 300WBY launching 180's at 3085 FPS with standard 2 PC Leupold medium bases, & Leupold rings.

WHAT GIVES?!?
How do I compensate for the 20 MOA rail when I'm running JBM to get close?
Do I even need to? Or is a 200yd zero a 200 us zero like I always assumed it was?
Very confused.
Here's a pic of Leupolds Catalog sub tensions in print, & my 180's in ink pen.
20 MOA RAIL & JBM Question-image.jpg
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  #2  
Old 08-28-2013, 08:04 PM
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Re: 20 MOA RAIL & JBM Question

If you are only using reticle holdover, the 20 moa rail should not change a thing, or even be necessary for that matter.

I don't like hold over anyway but thought I would offer what I could. May I ask why you don't just start dialing in for the longer shots? You have moa target turrets, correct? It is a fact dialing is more accurate for longer shots.

Jeff
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  #3  
Old 08-28-2013, 08:08 PM
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Location: Canterbury, New Zealand
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Re: 20 MOA RAIL & JBM Question

Have you got the magnification set to the correct triangle?
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  #4  
Old 08-28-2013, 08:41 PM
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Re: 20 MOA RAIL & JBM Question

Quote:
Originally Posted by Broz View Post
If you are only using reticle holdover, the 20 moa rail should not change a thing, or even be necessary for that matter.

I don't like hold over anyway but thought I would offer what I could. May I ask why you don't just start dialing in for the longer shots? You have moa target turrets, correct? It is a fact dialing is more accurate for longer shots.

Jeff
Thanks Broz, I thought a 200yd zero was a 200yd zero, but I'm glad you confirmed it.

I wanted to dial past 600 & have enough come ups to clear 1k with a 1" tube, thus the 20 MOA rail.
I greatly prefer the stadia lines for the close stuff, since it saves time. Why dial on 2-500 yd shots ? Having the 550 pin is just a bonus.

I don't mind dialing, but I'd rather range & shoot on the close stuff. I hear "I don't like the hold over thing" from a lot of folks. And that's fine. I do. I'm not afraid to dial when I get out far enough for it to matter. Unfortunately my rangefinder (Leupold RX-II) doesn't reliably range far enough to take advantage of dialing. I finally got the rifle capable of being serious at Long Range. Now I have to upgrade my ranging equipment.
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"Its not Rocket Surgery.....'
GOD,GUNS,&GUTTS MADE AMERICA, LETS KEEP ALL 3!winmag

"I have No idea why that cop made me ride in the back seat, when I Clearly called Shotgun!"
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  #5  
Old 08-28-2013, 08:44 PM
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Location: Redmond Or.
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Re: 20 MOA RAIL & JBM Question

Quote:
Originally Posted by kiwi3006 View Post
Have you got the magnification set to the correct triangle?
Yep, it was one of the first things I checked when I was that far off.

Still so confused as to what to do & how to fix this, short of having Leupold instal a standard fine crosshair, & having to dial all the time.
__________________
"Its not Rocket Surgery.....'
GOD,GUNS,&GUTTS MADE AMERICA, LETS KEEP ALL 3!winmag

"I have No idea why that cop made me ride in the back seat, when I Clearly called Shotgun!"
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  #6  
Old 08-28-2013, 09:21 PM
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Join Date: Feb 2007
Location: Townsend, Montana.
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Re: 20 MOA RAIL & JBM Question

Quote:
Originally Posted by winmag View Post
Why dial on 2-500 yd shots ? Having the 550 pin is just a bonus.
I see your point, and do not wish to de-rail your thread so I will only post this. You did ask.

Why? Because you are selling your rifle short by cheating it in accuracy. The difference between 450 and 500 has to be greater than 1 moa in your rifle and it is growing by the yard. There simply can not be enough aim points to keep up with the accuracy of the rifle. Plus I don't buy the "faster thing" Not if you would practice both ways. While you are finding that line among many lines, counting and rechecking, "oops it's in between those lines" ? (hope your not in between the wrong ones).. I will wheel my turret to the exact yardage and pin wheel what ever it is for dinner. I started long range with the hold over method. It worked until my rifles and I out grew it with distance.

I can see you are reaching out farther than before. That is way cool!!! But please keep an open mind to other options, you will need to adapt in some areas. Trust me.

I will not post here again unless I have a suggestion or idea in line with your original post.

Jeff
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  #7  
Old 08-28-2013, 10:13 PM
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Location: NW MT
Posts: 2,551
Re: 20 MOA RAIL & JBM Question

I have shot a system similar to your for years, B&C reticle,with CDS dial. It is faster and I never had problems. It was much easier for my 15 yr. old son to figure than dialing, he messed up the dial many times speed goat. This is before high speed, and zero stop. You should just match your drops to the listed stadia drops. Then verify, mine where always close with JBM. My son shot a speed goat at 550 with the B&C , with me spotting and short notice after a runfrom the goats, I was on lazer and would be hard to do solo. I prefer dial, but still use my tmr reticle for holds to 825. I have the mils and 1/2 marked accordinly
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