Scope/mount to rifle calculator?

[Impureclient]

I posted this on RFC in the CZ section and wasn't getting any bites. I figured that was the most direct source for questions about what to use on a CZ452. What I was ultimately trying to understand is if there is a way to calculate if scope A and mount B will fit on gun C?

In this case is a CZ452 lutra lux. Can I just look at the scope in question objective bells diameter and the ring height to see if it will fit the gun? Now in the case of an ultra lux, there is a rear iron site in the way so that would have to be accounted for if the bell end interferes with that. It either has to be in front of it(a 12" scope or less) or after it(15" or more) is what I've read on Eric Brook's site. I have narrowed down to either a or Simmons Whitetail Classic 6.5-20x 50mm or a Bushnell Banner 6-18x50. What I need is to know for sure which mounts will work and mount the scope the lowest. Is this a question for the scope, mount or gun manufacturer to figure out or do I just use the figures given by each manufacturer and measure if when combined the scope and mounts will both fit the gun before buying? I believe on Opticsplanet.com there was the option to ask their customer care about fitment. In a situation where you have a gun/scope/mount that nobody else has for comparison; are they able to theoretically calculate this with all the numbers or do you just order the gun you want, then scope and start trying and returning rings til they fit?

 

[45crittergitter]

In a situation where you have a gun/scope/mount that nobody else has for comparison; are they able to theoretically calculate this with all the numbers or do you just order the gun you want, then scope and start trying and returning rings til they fit?

I'm not aware of any such calculator, although undoubtedly there are some fit charts from some optics/mount makers for the more popular models with the more popular rifles. The problems come from several areas - not all ring and base makers use the same conventions when measuring their products (one maker's "low" ring may be about the same as the next maker's "medium"); rifles of the same model may vary in external dimension due to barrel profile differences, changes in bolt handles, varying locations or existence of rear iron sights, or etc.; and the fit may vary depending on how far you slide the scope fore or aft on the rifle. Not to mention that one maker's "50mm" scope may have an objective bell of a different outside diameter than the next maker's "50mm" scope.

A calculated/educated guess for your Plan B is probably where you are.

 

[gundudeusa]

Here's a calculator you can use.

It's got many modern scope and ring height preset values. Adjusts for Butler scope cover and also scope mount cant.

http://www.mil-rad.com/scope_ring_calculator

 

[B!ngo]

I may be misunderstanding the question because I believe that the answer is quite straightforward:
A= diameter of objective lens (or the larger of the two lenses) (for example 44mm)
B= center height offset of mounting ring (say for example 30mm) (you sometimes have to look at the specs to get the number rather than the listed low, or high)
So, if 1/2A < B you are GTG.
B

 

[45crittergitter]

That's oversimplified, Bingo.

The obj bell is only rarely over the plane (receiver) that the rings/base are mounted to. It's usually over the barrel. Barrel profiles vary widely, as do installed base heights relative to the bore centerline. Also, the fore/aft variance in scope location may affect whether the obj bell or the eyepiece interferes with the barrel, barrel-mounted sight, or bolt handle. And that's just for starters.

If you have a (for instance) Leupold scope with Leupold bases and rings and a Leupold mounting chart that lists your rifle with your barrel configuration, it may tell you which right height you need. That recommendation may or may not work with any other combination.

 

[greyling22]

rimfire central has a sticky where people posted what works for them. There is a pretty good chart. Did you happen to see it when you were there? did it help you?

http://www.rimfirecentral.com/forums/showthread.php?t=336921

there is a link to an updated spreadsheet at the top.

 

[Coltdriver]

I had a Steyr for which there was zero available information. And I wanted to mount a relatively huge 56mm objective scope on it.

So I made a profile of the scope in card stock. Then it was just a matter of getting it level over the receiver and getting the objective end as low as I was comfortable with then taking some measurements.

Sounds crude but I got it right the first time when I bought the rings and mounts.

I have owned a couple of CZ's. You will probably not be able to get the objective as low as you'd like because the bolt throw will have the handle touching the eyepiece. So if you do a mock up in card stock pay attention to where the bolt is when you cycle the action.

 

[greyling22]

ha! I thought I was the only one who drew out the dimensions of the scope on poster board. My wife thought I was way strange.

for a 50mm scope you will probably need high rings, and that may be a problem with the extreme comb drop in the lux guns. good luck.

 

[RustHunter87]

get some calipers take some measurements and use you brain
rings+ base +receiver has to be greater than (objective dia - tube dia)/2

I think, does that make any sense??

 

[jmr40]

You also have to consider the shape and location of the bolt handle. I've run across a couple of rifles, and a CZ-452 is one, where I had to mount higher than necessary for the bolt handle to clear.