Scope mounting: how low is too low?

[calvados.boulard]

Hi everyone,

I'm wondering if there is such a thing as mounting your optic too close to the barrel? I've got my scope mounted on my .22lr bolt action and when I hold the rifle up to the light I can see that they are not touching, but are damn close. I am able to pass a $5 bill between the scope and barrel, but I can feel that the bill is touching and being pulled by both the scope and the barrel when pulled between the two.

With respect to bolt clearance and ejecting of empty cases there is plenty of clearance.

Is this scope mounted too close? Is there any downside to such a close mounting?

Thanks for your help and expertise everyone,
Cal.

 

[bollox]

That is pretty tight. The barrel will expand a greater amount than the receiver as it heats up. I like about 2-3 mm clearance. You may be able to shim the bases, depending on the model.

 

[SIGP2101]

Idealy you want two zeros with every riffle and scope combination. If you go too low your first zero will be at less than 50m for sure. Is that what you want?
If you have ability to look through the bore while shooting theoretically you would have only one zero.

 

[calvados.boulard]

Idealy you want two zeros with every riffle and scope combination. If you go too low your first zero will be at less than 50m for sure. Is that what you want?
If you have ability to look through the bore while shooting theoretically you would have only one zero.

I'm not too worried about zeroing the scope. I had this same scope mounted on a similar rifle with extra high rings, and was able to zero where I wanted without issue. My main point of concern here is the proximity of the scope to the barrel. As Bollox pointed out the barrel will heat up, and therein lays my concern.

Thanks again for all of your help everyone,
Cal.

 

[Blastattack]

That is pretty tight. The barrel will expand a greater amount than the receiver as it heats up. I like about 2-3 mm clearance. You may be able to shim the bases, depending on the model.

You would have to heat your barrel to about 700 degrees Fahrenheit to expand the barrel by the thickness of piece of paper. That is unlikely to happen. However, I would be worried about the flex that occurs during recoil, as the barrel and scope may both "whip" enough to potentially contact. Likely not enough force to effect a .22, but still something worth noting. Besides that, there is no downside to being that close. The heat transfer would be minimal, and the scope would dissipate any heat acquired very quickly.

 

[stampede]

"I'm wondering if there is such a thing as mounting your optic too close to the barrel?"

How does it shoulder? Some rifles have a higher comb and are more comfortable with slightly higher rings.

 

[Canadian_Zuk]

Idealy you want two zeros with every riffle and scope combination. If you go too low your first zero will be at less than 50m for sure. Is that what you want?

It has nothing to do with "wanting" 2 zeros, that's just a fact of ballistics. If the scope is mounted above the bore at all, you get a near and far zero.

If you have ability to look through the bore while shooting theoretically you would have only one zero.

Yes, and it would be right at the muzzle as the bullet left the barrel and it would continue to drop from there.



OP, mount the scope so when you shoulder the rifle comfortable the optic aligns perfectly with your eye. A comfortable shooting position trumps any minor perceived advantages to near/far zero trajectory.

pickup your unloaded rifle with the scope set to maximum magnification and close your eyes. Shoulder the rifle comfortably and then open your dominant eye. Take note of what changes you have to make to your head position (cheek weld, head angle and eye distance to your scope) to obtain a clear sight picture. Adjust the mounting position of your scope until you have a perfect sight picture when you open your eye.

 

[Kryogen]

too close, jump one ring size

 

[SIGP2101]

I'm not too worried about zeroing the scope. I had this same scope mounted on a similar rifle with extra high rings, and was able to zero where I wanted without issue. My main point of concern here is the proximity of the scope to the barrel. As Bollox pointed out the barrel will heat up, and therein lays my concern.

FWIW this is a long range .22lr. It is a S3 8-32x56 mounted on a 25 MOA DIP rail on a CZ 452 American.
Thanks again for all of your help everyone,
Cal.

I know, but I was trying to make another point of concern. There is optimum setup for all things in life. Rifles/scopes as well. According to your own words it is your long range .22lr jig. Going to low you will run out of maximum useful range for that particular bullet. Defeats the purpose, my thinking anyway. Heat expansion is non issue as long as you can slide a sheet of paper but it will effect accuracy at long range but again non issue with .22s

 

[SIGP2101]

It has nothing to do with "wanting" 2 zeros, that's just a fact of ballistics. If the scope is mounted above the bore at all, you get a near and far zero.

Incorrect! For that statement to be true there are certain condition to be fulfilled. But I know what you wanted to say.

 

[metalbender]

The will be two zeros. The trajectory is not line of sight as seen through the scope. The angle of the bbl, although acute must cause the bullet to intersect the line of sight in it's arc at the first zero and again on the far zero. Basic physics.

 

[calvados.boulard]

Thanks for the suggestions on shouldering the rifle. Unfortunately this is a bench gun with a 56mm objective that won't ever be shouldered. The scope is mounted such that eye relief etc work for me. My only concern at this point is the closeness of the barrel and front objective. From what I've been reading and discussing with fellow range rats, having my scope so close to the barrel won't be an issue since it is only a .22lr, and barrel whip shouldn't be enough to close the tiny gap between the barrel and the front objective.

Sound legit?

Thanks again everyone,
Cal.

 

[Canadian_Zuk]

Incorrect! For that statement to be true there are certain condition to be fulfilled. But I know what you wanted to say.

you are correct

The will be two zeros. The trajectory is not line of sight as seen through the scope. The angle of the bbl, although acute must cause the bullet to intersect the line of sight in it's arc at the first zero and again on the far zero. Basic physics.

thanks for finishing my thought

 

[Drillbit]

It'll be fine. As long as it isn't touching.


I have seen 3 22lr rifles, however, with the scopes touching the barrels. The guys the have them shoot thousands of gophers every year without problems. Your gun is a bench gun, though, so I'm sure you don't want anything that could hinder accuracy. And piece of mind goes a long way!

 

[Andy]

This is new. So many people with scopes mounted so high that they have a chin weld, and we finally have the question if it's possible to be too low. It's easy for some people to over analyze this - we have people using iron sights where the eye is below where any scope sighting would occur and that's not too low for eye position for any stock I've ever had on a gun.

IMO, the lower the better as long as there is SOME clearance - forget the paper money and use a gauge. As mentioned, you can shim the bottom of the rings, but if it's shooting well there is no problem.

 

[DVXDUDE]

My 17hmr with a 6-18x50mm scope the barrel was about 1mm away from the objective.


Adjustable objective as well, When you would crank it down to 10 yards it would touch the barrel. Never had an issue with accuracy, It was a heavy barrel though and I never did heat the barrel up much.

 

[BigUglyMan]

The key is that if you can get a good cheek weld on the rifle and see through the scope properly without having to screw around too much while mounting the rifle (ie don't have to wiggle and squirm to get your face down in the stock) then you're good. Ideally you want the scope mounted so that you have a good solid cheek weld, especially with harder kicking rifles, and so that you can still see through the scope properly.

If you mount the scope too high you will be able to see through the scope fine but your cheek won't be in contact with the stock. This results in the stock getting a running start at your face when the rifle recoils. Think of the stock as "Terry Tate - Office Linebacker"...better to be right tight to it when it starts to move rather than letting it build up a head of steam before smashing into your face. You often run into the problem of a stock with too much drop at the comb (see the CZ magnums with the Euro stock) and a high mounted scope. When they hit you it feels like someone is trying to take your cheekbone off with a cold chisel and a 3lb hammer.

Also keep in mind that there are a wide variety of facial layouts out there. What works for me might feel like a bad day in the boxing ring for you. My father loves Leupold Super Low rings to tuck his scopes down as much as possible. This setup also works for me. But if you have lower cheekbones than we do you might not even be able to see through the scope properly and firing might be painful. Conversely, if I shoot a rifle set up for someone with low cheekbones and the rifle is, vigorous, then I'll get a rather unpleasant whack in the face.

At the end of the day you probably want to try a couple of different combinations to find what fits you properly. You want to be able to mount the rifle smoothly and have your eye line up with the scope naturally and have a solid cheek weld with no fiddling around. If the scope is set up properly your eye will naturally settle behind the scope and your cheek on the comb/cheekpiece as you mount the rifle.

I would never have a scope touch the barrel but minimal clearance (ie visible light) is just right. If the bolt runs and the cases eject you're laughing.