Home Forums Hunting & Shooting Hunting Optics Scope height vs bore line....

As a young gun nut I was always taught that a scope should be mounted as close to the center of the bore line as practical. I was told that cheek weld and proper eye alignment were two major reason for this - bolt lift geometry can also be a consideration.

So, my point.... I’m watching a tv hunting program involving a couple that have one rifle in particular that drives me crazy. It’s a Browning product with a 60* bolt lift. It features an adjustable comb, which is cranked up pretty high to accommodate the scope which looks to be mounted about 3” above the bore line. There’s plenty of room to drop that scope a good inch or more closer to the barrel - and yet, there it is...? Why would anyone do that?

It’s their rifle and they can put it together anyway that suits them, but I see no practical advantage and maybe some questionable disadvantages. It seems like the math geometry would favor a scope mounted lower close to the barrel and bore line of sight....

What are your thoughts?

Rick and Julie Krueger (?)? Her rifle was like that. I wondered the same.

Hey
Yep

I have seen several like that. Saw a guy with a Ruger 450 with a riser picatinny scope mount. Probably at least 2" between the scope and barrel.

I like my eye to fall directly behind the scope with very little sensory input. That's about 1 1/4 to 1 3/8 inch above the center of the bore line. I realize that is higher than some folks like but I have a hard time getting my face down to the scope with anything less. 3 inches is way out of line the other direction but I don't tell folks how to set up their scopes. I can only guess that is where he or she wants it to be.

kwg

They’re hunters and not gun people? I remember back when see through scope mounts were popular😂

For most hunters, shooting at reasonable distances lower is better. For long range target shooting there are advantages.

With a typical hunting rifle with a scope 1" above the bore zeroed at 100 yards the bullet will never be more than 1" above, or below line of sight from the muzzle out to 130-150 yards depending on the cartridge and load, beyond that will always be low and predictable.

But when you start putting the scope 2" or higher you change the angle. With a 100 yard zero you end up with bullets 2" below where you're aiming up close and you could be 2-3" high at some point past 100 yards before dropping down again to zero.

All bullets have 2 zeros. Once when going up, the 2nd when coming down. Most of us with a 100 yard zero are actually zeroed at around 25 yards the 1st time. The bullet is on it's way down at 100 for the 2nd zero. With the scope mounted that high the 100 yard zero is the 1st one. It will also be zeroed again at 200-300 yards and be high between 100 and the 2nd zero.

Mounting it that high gives you more adjustment to your scope at long range, but can complicate things at the very ranges where most shots are taken in my opinion. But if you are planning on only taking 400+ yard shots it can be an advantage.

I usually like scopes mounted fairly low and I almost never use objectives over 44mm. Mostly I use medium and low rings so most of my scopes are around 1.5 inches above the bore on bolt actions. On AR-15's they are a bit higher due to Picatinny rails and the way AR's are configured.

But everyone has their own personal preferences.

That was also the "common wisdom" when I was a young rifle loony--but that was back when most commercial rifle stocks were primarily designed for "iron" sights. Consequently a good cheek-weld required the scope to be mounted as close as possible to the same height as open sights--which were often higher in some of that era's newer factory rifles, due to that factor.

Today's rifles usually have stocks designed for scopes.

Mounting the scope higher over the bore line can have a lot of advantages.

A lot of this is dependant on stock fit.

A stock with a higher heel and comb controls recoil better as the recoil moment is more inline with the shoulder.

The AR is an example of the heel being directly inline of the bore line. This does require an optic to be fairly high above bore line but it works very well.

For very close range there is quite a bit of offset but that's workable. The max point blank range is extended a bit if that matters.

Now if the stock is a conventional stock with a lower comb then mounting the optic high seems sub optimal.

Whatever is comfortable for the shooting one does.



For what it is worth I got over the 'must be low' when I picked up a 20's era Waffenfabrik with Zeiss Zielvier in factory fitted Akah mounts and found it as easy to shoot accurately as any other, and more comfortable than some when standing up.

Still a good rule of thumb when scoping a levergun as most of their stocks are designed for use with iron sights. Drives me crazy to see scopes mounted a mile high on a classic Marlin levergun.

[quote/] Whatever is comfortable for the shooting one does.

For what it is worth I got over the 'must be low' when I picked up a 20's era Waffenfabrik with Zeiss Zielvier in factory fitted Akah mounts and found it as easy to shoot accurately as any other, and more comfortable than some when standing up.[/quote]


That’s the thing. They use several other Browning rifles that are all scoped lower in a conventional manner.

I’ve shot older European rifles with high claw mounts and find them really hard to shoot, since my cheek isn’t in proper contact with the stock - I’d rather use the irons....

AR's pretty much changed the 'lower is always better rule'. As long as you are in consistently repeatable position, you are good.

Yep, bolt actions with 40mm objectives are generally 1.5" above the center of the bore line. AR's and some of my precision rifles are more like 1.8" above the center of the bore line. Most guys are not running 1", as they think they are. They are probably more like 1.5", as that is very common.

The higher off the bore line, the more the chance for things to go off skew if the rifle is canted. It is all about geometry, or trigonometry, more like it. A scope super high off the bore centerline, like what the OP is describing, offers no benefits when it comes to shooting way out there (past 500 yards). It increases the error if the scope is canted.

Yep!

Maybe it’s a sponsors product and must be visible?

Osky

The orginal iron sights on the AR are 2.650" over bore line. I doubt you are lowering the optic down to 1.8" over bore line.

2.765" over bore line is considerer 1/3rd lower co witness and most find that height pretty close to optimal for a scope mounted AR but some mounts go much higher.

The often refered 1.930" mounts are 3.055" over bore line +/-. Most mounts for the AR are speced from the top of the rail but that's not the real controlling dim in the Pict Spec.

I've noticed our member and gunsmith Al Nyhus posting some rifles with the scope very high above the bore, and I would guess these are some pretty good shooters.

Fixed distance with relatively heavy BR guns that you barely touch are a different ball of wax.