I was starting to zero my 16" Grendel barrel the other night. I bought a new Zeus 5 thermal scope and thought that if I got on zero at 25 yds that it would be a good starting point for 100 yd shots. At 25 yds I could not get my round any closer than 8" in elevation, they were all low by that much and I ran out of adjustment on the scope. Shooting 123 gr Amax Hornady factor loads. I think this scope is defective and plan on sending it back to the manufacture. Am I missing something here?
My other night vision scopes zero fine but this is my first thermal. Where should I be on the target at 25 yds with a 100 yd zero. I'm not wanting to be exact but just in general.
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02-28-2014, 04:17 AM
(This post was last modified: 02-28-2014, 04:29 AM by Kikn.)
I'm thinking it would be close to 1.5" low at 25 yards to have a 100 yard zero
No Paul...the mount has 2 QD levers and the mount is longer. I'm quessing 5".
Insert the distance between the center of the bore and the center of the sight into a good ballistics program. Run it for the distance zero you want and then check the 25 yard elevation.
No I can't. I looked at that and there's no way, good advise though. The guy at Armasight asked me to try and shim the mount and I told him "no way". I spent a ton of money and shouldn't have to shim a scope of this value. They are sending a call tag and the scope goes back overnight shipping Monday. They seem to be doing right by me as of now. We'll see
It ain't bad, JBM gives 1.8" low at 25 yd for a 100 yd zero.
On the other hand, you could raise the 25 yd zero a half-inch to 1.3 inches low at 25 yd. That would get you 1,5" high at 100 yd and on a ground squirrel out to over 200 yards and in the hog's boiler room out to over 250 yards.
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Shivesy Wrote:Okay....ya got me thinking about this quote so I decided measure the best I can. Center of bore to center of scope lense is 2 7/8". I shoot Hornady 123 gr. factory A-Max ammo. 16" bull barrel. 1-8.5 twist.
Help me out here with the info I just listed. Where should I be at on paper when I am zero at 100yds. Kikn says around 1 1/2" low, does his estimate concur?
Kikn is right, it's 1.6" low at 25yds.
Get to know the JBM calculator which is free online. Just plug in all your variables and you get a solution;
http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi
2 7/8" is a big separation between barrel and sight so can I suggest you be very careful your gun is exactly vertical when taking any shot. the greater the separation the more canting will confound what you are trying to hit.
Something is definitely not right in your case. My money is on '52's thinking, that the platform has inbuilt cant and is back to front.
I was just making sure my thoughts were correct in thinking that being 8" low at 25 yds was way off. I have adjusted the cross hairs down as far as they can go on my digital screen and 9" low @ 25 yds was as high as the bullets would raise on my target. I'm out of any kind of manual adjustment on this unit. I just didn't think wasting ammo was in my best interest. This scope leaves tomorrow and Armasight is going to send it to their lab for testing. Thanks guys
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