Running out of elevation CZ457 MTR XRS

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Baked Potatoe

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Good day all

I have a CZ457 MTR in XRS chassis. Vortex venom 5- 25x 56 objective with 34mm tube on a 20 MOA base rail. All equipment mounted correctly and torqued to spec tolerance.

My conundrum is when I zero at 50m it only leaves me with 13.6 mils of upper travel which is insufficient for 300m.

I have ordered a 40MOA rail to alleviate this.

What would cause all the travel to be eaten up so much elevation in the 50m zero ..?
Any help and knowledge would be greatly appreciated.

Note: when zeroed at 50m it put most through the same hole with a little variation. Accuracy not affected.

Cheers and have a great day
 
I would agree with the above comment. I have a 457 varmint with a 20 moa rail and an el cheapo Vector Veyron scope on it with to get to 300 with no issues.
 
Easiest is to shim the scope until your sr zero is well under 1 revolution of mechanical bottom on your scope. No need for a zero stop then... so remove it. Now you should have the full mechanical "UP" of the scope.

Jerry
 
What is the overall vertical travel of that scope with and without a zero stop?

13.1 milrad is 45moa.
So 90moa overall travel?

My strike eagle wasnt much more than that if i recall.

The 5-25x56 venom is 25 mrad total by spec.

Your 40moa rail will do it but a scope with more travel might be in your future.
 
I’m running an area 419 30 moa mount with an extra 10moa in Burris XTR Signature rings while keeping the zero stop intact. The zero stop should always be used. It’s proper long range form to dial back down to zero after engaging targets a Revolution Up. I have no issues shooting 300m with this setup.
 
I'm running a 40 MOA MDT rail on my 455 with a RITON 6-25 x55, and I can dial from 20 yards to well past 300 with it. I still have a couple of MOA left below 20.
 
That sounds about right to me.

Roughly speaking it takes about 20moa or 5.8mrad just to get to 50. Your scope has 85moa/25mrad without the zero stop engaged. So you're close to optically centered and the rail incline is getting you to 50.

Theoretically speaking...if you put a 60 rail on there youd be 1/2" high at 50 with the elevation turret jammed tight in the basement. Or a 50moa rail and youd be 2.9mrad from bottoming out the turret.
 
Mysticprecision said:
Easiest is to shim the scope until your sr zero is well under 1 revolution of mechanical bottom on your scope. No need for a zero stop then... so remove it. Now you should have the full mechanical "UP" of the scope.

Jerry
Click to expand...

Can you explain the process of shimming a scope? Ive read about it here and there...but the process seems to only go as far as someone saying TO shim, rather than how to. Where do the shims go? Does a guy shim, and then lap and bed?
 
Sight it in at 25 or 50 with standard rings; dial it down to see how much down adjustment your scope has. If it is over 30 but under 40, buy a 30 MOA rail. If over 40 buy a 40. Over 20 but <30, buy a 20.

It seems that most like to overcomplicate this process.
 
fiftycalforsquirrels said:
Can you explain the process of shimming a scope? Ive read about it here and there...but the process seems to only go as far as someone saying TO shim, rather than how to. Where do the shims go? Does a guy shim, and then lap and bed?
Click to expand...
You can use 'solid' rings and a scope base with a large amount of cant (40moa to 60moa)

or you can use Burris Signature ZEE rings with inserts. I really like the XTR Signature rings for the amount of shim offered in the inserts, robust construction, and metal to metal parts to secure to base. Used these on all my competition rifles for many years and they have always worked... even with Air Canada has destroyed parts of the rifle.

I prefer a combo of both so I can fine tune my shim to get close to the mechanical bottom of the scope travel AND as centered in windage as possible. This leads to the most elevation useable without risk of windage wander as the erector guts hits the inside of the scope tube.

Manfs try and reduce this risk but setting the windage travel much lower vs the elevation.

Jerry
 
Mysticprecision said:
You can use 'solid' rings and a scope base with a large amount of cant (40moa to 60moa)

or you can use Burris Signature ZEE rings with inserts. I really like the XTR Signature rings for the amount of shim offered in the inserts, robust construction, and metal to metal parts to secure to base. Used these on all my competition rifles for many years and they have always worked... even with Air Canada has destroyed parts of the rifle.

I prefer a combo of both so I can fine tune my shim to get close to the mechanical bottom of the scope travel AND as centered in windage as possible. This leads to the most elevation useable without risk of windage wander as the erector guts hits the inside of the scope tube.

Manfs try and reduce this risk but setting the windage travel much lower vs the elevation.

Jerry
Click to expand...
Oh ya I see.... the Signature Zee's are decent... Still on the fence about XTR Sigs.. maybe I just got a lemon set. I thought maybe you were referring to use literal shim stock. I had come across that a few times in really old threads but it wasnt expanded on.

Fair point as well about being relatively true on the windage in order to maintain all of the elevation travel.
 
You can shim a One-piece base in many cases, depending on the brand and how flexible it is Not. You don't want it to flex IMO. And you do NOT shim individual ring as that can bend the scope when tightened down.
 
PS - Here's a link to an 'older' thread about shimming scopes. Info from @JBelk, if that rings any bells. And some alternate 'solutions' to this issue. Only 26 Posts in total. http s://www.shootersforum.com/threads/out-of-adjustment.173025/
 
A LONG time ago, I bought 2 brass 20 MOA tapered shims from a member here. Not sure if he's still on here or not. The idea was to mark the position of the scope bases with a permanent marker, both front & back, BEFORE you cut the shim, then install them in the correct position. I did, and, as a result, was able to obtain 3 sets of 20 MOA tapered shims for 3 different rifles, all marked correctly, of course, from the 6" piece of tapered brass.

That is the only way to obtain a 20 MOA shim, when specific bases are unavailable for your particular rifle other than, as has been mentioned, using Burris Signature rings, with the appropriate offset shims, without bending your scope's tube, which is NOT good.
 
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