Author Topic: Determining bore axis (Read 698 times)

Stoots · « **on:** July 22, 2003, 02:57:09 PM »

Gentlemen. Now that my SRH/Leupold combo is mounted and ready, I'm wondering if my scope/bore axis is correct. As I didn't have and tools for this purpose, I used a plum line on the wall and did the best I could by sight. How do/did you all mount scopes? What kind of accuracy issues are there if it's a fraction off? Sorry to keep pestering you all, but the perfectionist in me can't stand any more lost sleep!
Thanks in advance for any opinions or comments!
Jason Stoots

KN · « **Reply #1 on:** July 22, 2003, 03:54:52 PM »

When it comes to pistols it can be a little tough to define exactly where square to the world is. My sugestion is to use your plumb line like your doing but close your eyes as your setting your pistol on the bag,(or however it is your setting it). Then open them and see if your scope looks level. You'll find that you have a natural feel for holding the pistol and the scope should be set pretty much for that. If not you'll probably end up canting the pistol in the field. Hope this made some kind of sense. KN

Jeff Vicars · « **Reply #2 on:** July 22, 2003, 04:19:06 PM »

If you are using a Weaver type base, B-Square has a level that fits the slot. This level allows you to precisely level your gun, then use the plumb line to line up the vertical crosshair. Fool proof.

Bullseye · « **Reply #3 on:** July 22, 2003, 05:39:39 PM »

I feel your pain. I have a hard time getting them square. I use a line on the wall like you did and do the best I can. Usually when I shoot the gun at the range the first time any problem becomes apparent and I adjust the scope if needed.

Duffy · « **Reply #4 on:** July 22, 2003, 09:35:31 PM »

I usually put the gun in a padded vise and use either the rear sight blade or the top strap to level the gun with a very good level. Then align the scope just as your doing with the vertical line. Only problem with using the top strap is if the polishing guy at the factory got a little heavy on one side it could be off. I noticed on my Encore nothing is square with the world. Sometimes the old eyeball treatment works the best!

Questor · « **Reply #5 on:** July 23, 2003, 02:17:05 AM »

I get it as close as I can, then I shoot the gun for a while. If something isn't right, I adjust.

Mikey · « **Reply #6 on:** July 23, 2003, 03:59:31 AM »

Stoots: Questor has a sound suggestion. Mount the darn thing up and then go shooting. Start at 25 yds and use a fresh backing for the target so you can see where she hits.

I don't know if you can get the firing pin out of the frame on that ruger but if you can, without terrible difficulty, sight down the bore from the firing pin hole and line up your scope accordingly. You can do that with a Smith and Wesson very easily by just taking the hammer off and looking down the barrel through the firing pin hole. That helps line up adjustable sights as well. It's like bore sighting a rifle with the Mark I Eyeball. Hope this helps. Mikey.

Jeff Vicars · « **Reply #7 on:** July 23, 2003, 05:36:50 AM »

Mikey, I think Stoots is asking about how to mount a scope straight, not bore sighting.

Double D · « **Reply #8 on:** July 23, 2003, 05:47:28 AM »

You can get real close, as close as you need for a hunting piece using two steel rulers of the same length. 6 inchers will work, 12 inchers are nice.

Put your firearm in a vice. Take the caps off the top turret of your scope and lay one of the rulers across the turret. Lay the second ruler across a flat square spot on top of the firearm. Top of the receiver, top of scope base anything that is square will work.

Move to the end o f the firearm and look down the firearm so your visual perspective is such that the ends of the rulers appear to be vusually one above the other. Rotate the scope as need to make the end of the rulers appear parallel. Tighten scope. Recheck with rulers.

BCB · « **Reply #9 on:** July 23, 2003, 11:59:58 AM »

Stoots,

For most practical purposes, precise alignment with bore axis doesn’t matter. I mount all my ‘scopes by placing the ‘scope loosely in the rings and then holding the handgun/rifle as I would when I am shooting it. It if doesn’t look like the crosshairs are at 12…3…6…9, I turn the ‘scope to accomplish this alignment. My handgun ‘scopes are all at about 11:30 for the top crosshair and my rifles are at about 12:30 for the top crosshair. Or slightly to the left of dead center for handguns and slightly to the right of dead center for rifles. It is just the way I hold the weapon. They appear to be precisely aligned at 12:00 when I hold the weapon. People who shoot my rifles/hanguns notice this crosshair placement. So what! It shoots to point of aim for me and the same for the other person—or so dang close that no one will ever know!! It is just to slight of a problem to worry about it. If the particular weapon is sighted-in for you, it will work at all ranges…I mount ‘scopes rotated a full 90° counter clockwise on my Model 94 Winchesters so that the top ejected case doesn’t hit the left/right adjustment knob if the ‘scope is mounted as it is supposed to be! Left/right becomes up/down, and up/down becomes left/right!!! Mount the ‘scope for what is comfortable visually for yourself and sight it in and go shoot some targets!!!!Good-luck…BCB