Ring Height Question 12 FV 30mm

[J.Baker]

Per Vortex's website:

Objective O.D.: 2.3"
Main Tube O.D.: 30mm or 1.181"

Half the Objective O.D. would be 1.15" and half the main tube O.D. would be 0.590"

The Action O.D. is 1.350" while the shank of the barrel just ahead of the nut will be 1.120" at the most (large shank). So right there you already have just shy of a 1/4" gap for the objective bell so no need to add a gap distance into your calculations.

So now you know you need the centerline of the scope rings to be a minimum of 1.15" above the top of the action.
Subtract the height of your base above the action from that 1.15" figure and that will tell you how high the rings need to be (to the centerline of the rings).

If the ring manufacturer gives the height dimension to the bottom of the ring saddle, simply subtract 0.590" (1/2 of 30mm main tube diameter) from yoru height figure from above to get the height to the bottom of the saddle.

[Mozella]

Per Vortex's website:

Objective O.D.: 2.3"
Main Tube O.D.: 30mm or 1.181"

Half the Objective O.D. would be 1.15" and half the main tube O.D. would be 0.590"

The Action O.D. is 1.350" while the shank of the barrel just ahead of the nut will be 1.120" at the most (large shank). So right there you already have just shy of a 1/4" gap for the objective bell so no need to add a gap distance into your calculations.

So now you know you need the centerline of the scope rings to be a minimum of 1.15" above the top of the action.
Subtract the height of your base above the action from that 1.15" figure and that will tell you how high the rings need to be (to the centerline of the rings).

If the ring manufacturer gives the height dimension to the bottom of the ring saddle, simply subtract 0.590" (1/2 of 30mm main tube diameter) from yoru height figure from above to get the height to the bottom of the saddle.

What you say is all good information. However, when shopping for rings, it's not always as simple as your guide implies even though what you say is correct.

First of all, it's not always easy getting a height reference for a particular scope ring. Some manufacturers make "low", "medium", "high", and sometimes "extra high". Finding actual numbers is often much more difficult than you might hope. And sadly one brand of "medium" might be higher than another brand's "high".

Some, as you point out, give height to the bottom of the saddle and some to the center of the scope. Use caution here.

And where is the other end of that height dimension. For those rings which go on a Picatinny Rail you have to ask yourself, is the bottom reference to the top of the rail or the edge where the ring grips the rail. Unless you can find a drawing, that information is hard to find. And how high is that pesky picatinny rail anyhow? Some are thick and some are thinner.

The objective O.D. that is important is NOT the size of the glass. Size of glass is an important performance data point when shopping for scopes because it has to do with how much light the scope can gather. The size of the glass is easy to find and is included in the model name in almost every case. But when fitting the scope to the barrel, you need to know the OD of the housing. In some scopes that's not much more than the size of the glass while in others the difference is significant. If your scope uses a front lens cap which slips OVER the scope, you need to include that factor into your clearance calculations or possibly switch to a different type of lens cap.

Finally how about bases and barrel contour? When you fit a 20mm base you're effectively tilting your scope down in the front. That reduces the clearance between the front part of the scope and the barrel. Remember your high school trig? If so, you can do the math.

Those with a bull barrel will have less clearance than those with a hunting profile. Both the base tilt and barrel profile may require some real digging to get good answers for those trying to get the absolute minimum clearance between barrel and scope.

When you start down this path, especially if you're goal is minimum clearance, be sure to stock up on plenty of cheap whiskey. You're gonna' need it.

[J.Baker]

What you say is all good information. However, when shopping for rings, it's not always as simple as your guide implies even though what you say is correct.

First of all, it's not always easy getting a height reference for a particular scope ring. Some manufacturers make "low", "medium", "high", and sometimes "extra high". Finding actual numbers is often much more difficult than you might hope. And sadly one brand of "medium" might be higher than another brand's "high".

Some, as you point out, give height to the bottom of the saddle and some to the center of the scope. Use caution here.

And where is the other end of that height dimension. For those rings which go on a Picatinny Rail you have to ask yourself, is the bottom reference to the top of the rail or the edge where the ring grips the rail. Unless you can find a drawing, that information is hard to find. And how high is that pesky picatinny rail anyhow? Some are thick and some are thinner.

The objective O.D. that is important is NOT the size of the glass. Size of glass is an important performance data point when shopping for scopes because it has to do with how much light the scope can gather. The size of the glass is easy to find and is included in the model name in almost every case. But when fitting the scope to the barrel, you need to know the OD of the housing. In some scopes that's not much more than the size of the glass while in others the difference is significant. If your scope uses a front lens cap which slips OVER the scope, you need to include that factor into your clearance calculations or possibly switch to a different type of lens cap.

Finally how about bases and barrel contour? When you fit a 20mm base you're effectively tilting your scope down in the front. That reduces the clearance between the front part of the scope and the barrel. Remember your high school trig? If so, you can do the math.

Those with a bull barrel will have less clearance than those with a hunting profile. Both the base tilt and barrel profile may require some real digging to get good answers for those trying to get the absolute minimum clearance between barrel and scope.

When you start down this path, especially if you're goal is minimum clearance, be sure to stock up on plenty of cheap whiskey. You're gonna' need it.

Actually, it really is just that easy if you're willing to do some legwork.

1. Getting the required information is as easy as calling or emailing the manufacturer if they don't have it on their website or if it's not clearly defined on their website. Your argument doesn't hold water.

2. As for "medium" or any other height being different between different brands or even different styles from one brand - That's why you need to do some RESEARCH. The internet and telephone are your friends if you'd just use them effectively. Again, this argument doesn't hold water.

3. Caution with Saddle Height v. Centerline Height - That's why I pointed out the difference between the two in my previous post.

4. Where is the end of that height dimension? How high is the rail? Again - the internet and phone are your friends - you just have to use them effectively.

5. Objective O.D. - If you had actually looked at Vortex's website you would see that the measurement I gave (2.3") was for the O.D. of the objective bell (that's the housing) - NOT the lens. 50mm is 1.9685" in diameter.

6. Lens Caps - Apparently you missed where I pointed out the +/- 1/4" difference (0.230" for a large shank; 0.300" for a small shank) between the diameter of the action (1.350") and the max possible diameter of the barrel shank (1.120") where the threads and nut end. There's your needed gap for any kind of cap you want to run. That's why I pointed it out in my first post - you don't need to factor it in because it's essentially built in with the action/barrel diameter difference. Even with a full bull shouldered barrel you'd still have 0.100" clearance with a typical 1.250" diameter barrel blank which nobody does.

[Robinhood]

Actually, it really is just that easy if you're willing to do some legwork.

Yep, But not as easy as having someone else do it for you.

[Mozella]

Actually, it really is just that easy if you're willing to do some legwork.

1. Getting the required information is as easy as calling or emailing the manufacturer if they don't have it on their website or if it's not clearly defined on their website. Your argument doesn't hold water.

..... snip...............

You completely missed the point of my post.

It's obvious your idea of "easy" and mine are different. I have a life and spending time on the telephone, (after holding for "the next available agent" for ten minutes) talking to some young lady who doesn't have a clue about the product in question is not my idea of "easy". Emailing and waiting for a reply, which often doesn't ever come, isn't my idea of "easy" either.

Of course, you do what you have to do when there is no choice. When I shop scope rings I do plenty of legwork, but not because I enjoy wasting my valuable time. I do it because there are no standards for this aspect of our sport coupled with the fact manufacturers have wildly different policies regarding publishing specifications. Some are OK and some guard their specifications as though they are national secrets.

Let me see if I can clarify my earlier post.

In an ideal world, you could log on to a web site and find a specification sheet listing the OD of the objective end of the housing of a scope along with length, weight, and all the other things you might need to know for this or some other bit of research. Then, with another few clicks, you could find the OD of your action. Your barrel manufacturer would publish the barrel profile too; not just list "heavy varmint" and leave you guessing. And if would be wonderful is ALL the ring manufacturers would include a detailed drawing showing the specifications of all their hardware. Then, as icing on the cake, some clever forum cowboy could publish a chart showing how much clearance is lost with a 20 or 30 MOA rail.

In fact, you can't do the required research with a few clicks. And a few clicks is all it would require if this task were truly as "easy" as you claim, unless of course you like spending time on the telephone or prefer to wait for an Email reply which may or may not ever arrive. I don't.

Depending on the various brands in question, you have to dig deep to find the truth, especially if you're looking for the smallest possible gap between the barrel and scope. But it need not be this way if manufacturers gave a little more thought to how their customers use their products.

I mounted my first scope almost sixty years ago and it was indeed easy because I had only one choice back in the day. Part of the problem these days is that we're spoiled for choice. There are countless combinations and that's why specifications and drawings are so desirable.

I stand by my previous post and I maintain that there are some very real and largely unnecessary frustrations when shopping for scope rings. Yeah, the answer can be found, but "easy" is not an appropriate description of the process.

[J.Baker]

You completely missed the point of my post.

It's obvious your idea of "easy" and mine are different. I have a life and spending time on the telephone, (after holding for "the next available agent" for ten minutes) talking to some young lady who doesn't have a clue about the product in question is not my idea of "easy". Emailing and waiting for a reply, which often doesn't ever come, isn't my idea of "easy" either.

Of course, you do what you have to do when there is no choice. When I shop scope rings I do plenty of legwork, but not because I enjoy wasting my valuable time. I do it because there are no standards for this aspect of our sport coupled with the fact manufacturers have wildly different policies regarding publishing specifications. Some are OK and some guard their specifications as though they are national secrets.

Let me see if I can clarify my earlier post.

In an ideal world, you could log on to a web site and find a specification sheet listing the OD of the objective end of the housing of a scope along with length, weight, and all the other things you might need to know for this or some other bit of research. Then, with another few clicks, you could find the OD of your action. Your barrel manufacturer would publish the barrel profile too; not just list "heavy varmint" and leave you guessing. And if would be wonderful is ALL the ring manufacturers would include a detailed drawing showing the specifications of all their hardware. Then, as icing on the cake, some clever forum cowboy could publish a chart showing how much clearance is lost with a 20 or 30 MOA rail.

In fact, you can't do the required research with a few clicks. And a few clicks is all it would require if this task were truly as "easy" as you claim, unless of course you like spending time on the telephone or prefer to wait for an Email reply which may or may not ever arrive. I don't.

Depending on the various brands in question, you have to dig deep to find the truth, especially if you're looking for the smallest possible gap between the barrel and scope. But it need not be this way if manufacturers gave a little more thought to how their customers use their products.

I mounted my first scope almost sixty years ago and it was indeed easy because I had only one choice back in the day. Part of the problem these days is that we're spoiled for choice. There are countless combinations and that's why specifications and drawings are so desirable.

I stand by my previous post and I maintain that there are some very real and largely unnecessary frustrations when shopping for scope rings. Yeah, the answer can be found, but "easy" is not an appropriate description of the process.

Heaven forbid you're inconvenienced in the slightest or actually have to exert some effort to get the information you want.