Firearm Forums - Arms Locker banner

Precision mounting of a scope?

3318 Views 10 Replies 7 Participants Last post by  brass hammer
You know, this has bothered me for a long time.

I will mount a scope on a new rifle, using bubble levels, little doodad alignment devices and everything I can think of, but there is this little nagging feeling that I am still not doing it correctly. I guess what I want is to have the absolutel rock steady confidence that if I sight in my scope at 100 yards, clicking the elevation knob for a marker at 300 yards will NOT cause the point on impact to drift even a hair horizontally.

But no, I don't feel that way at all. Too much room for error when I level the receiver of the gun with the scope mount installed. Then I bubble level the scope, trying not to move anything while I tighten everything down. So is it perfect? Heck, I doubt it. How precise is a bubble level anyway?

So how do the experts do it? How do you precisely mount a scope so that there is NO lateral movement at all of the bullet impact when you adjust the elevation setting on the scope?
1 - 11 of 11 Posts
Thanks, JJ #13. I looked it over, but it looks just like the procedure I have been doing, more or less. Just how precise is using a bubble level? I'm thinking about getting one of those electronic levels as they might be more accurate for getting true readings. Eyeballing where the air bubble is in the tube just is not going to be precise enough, IMHO.

I've heard of the technique where you hang a plumb line from a stand and line up the vertical cross hair in the scope. But I'm not sure about how to make sure the barrel is dead center under the scope and the receiver squared.

Yeah, maybe it just doesn't matter for the kind of shooting I do, but after doing a little bit of metal working, you learn to respect thousands of an inch.

The plumb line method works very well... just make sure that you level the rifle at each stage of scope installation to ensure that the stadia are correct on the line when you gauge it.

The level is pretty accurate. Of course, there is some variation due to differences in the persons using the gun.

The important thing to remember is to use the proper torque pattern on the screws/bolts/nuts.. what have you. That will throw you off big time.

I'm glad Hard Rock listed his web page. It's a good 'un, and in fact I printed it off to take home when I mounted my new Badger base and rings just to make sure I hadn't missed sumthin!

One other thing: Once you get her all mounted up, lay the rifle back in the cradle. Then, use a plumb line down the center of the buttplate (just eyeball it so that the string drops straight down the middle of both buttplate screws) to make sure that the stock - not the rifle, but the stock - is vertically plumb. Then, put your level back across the top of the top turret of the scope to verify that it is still laterally level. I have found on more than one occasion that the the scope is no longer laterally level even though the butt plate is straight up and down. The culprit usually turns out to be that the base mounting holes in the receiver are off center. That sucks a lot, because as I understand it, it's iffy tryin' to fill the old holes and drill new ones because the temper of the receiver can be altered.

See less See more
I just stumbled across this old thread. I suppose this is common knowledge, but here's what I do to verify the alignment. I get a large chunk of cardboard, like the size of a refrigerator box. I then place a strip of 3/4 wide black masking tape vertically down the center of the cardboard from top to bottom. When I attach the cardboard to my backstop, I plumb the line as close as I can get with a four foot level. Getting the tape absolutely plumb is critical and worth the time it takes to be anal about perfection.

I place my target near the bottom of the backstop and shoot a group at 200 yards verifying the group is centered on the tape. Center the vertical cross hair on the tape to eliminate cant. Then I crank the scope up a bunch, like 20 MOA and shoot another group. The second group should be 40 inches high dead centered on the masking tape. If not, loosen the scope and rotate it a tiny little bit toward the second group and repeat the procedure.
Good idea, Ankeny. Your method verifies a number of things - your are also making sure that nothing else is fubar, from the condition of the crown on your muzzle to your physical shooting mechanics.

mounting a scope

Another good thread.
Rich mentioned something about a digital level.
I use one of these to set propeller pitch, (zero the level to whatever reference you want to be zero/not if a bubble thinks it's at zero).
There might be cheaper prices as I paid about $150 for mine.
Hope this helps.

The culprit usually turns out to be that the base mounting holes in the receiver are off center. That sucks a lot, because as I understand it, it's iffy tryin' to fill the old holes and drill new ones because the temper of the receiver can be altered.
I got some Burris rings that have plastic inserts that will compensate for this (mounting holes off center). It takes a lot of range time to get them just right. If I remember right they are called Burris Z rings.
I didn't realize how old a topic this was. This has probably been addressed quite a few times by now.
the only-'oneness' of "SCOPED/RIFLE/SHOOTER"
is the simple FACT,,,OF SHOOTIN'!!!,,,!!!

[although, I've found a $199.00 TARGET/SCOPE-REST "giz-mo' RANGE [email protected] sportsman-warehouse.]

WHY CRY? :dgrin:
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.