mounting scopes straight

roklok · Posted: Mon Jul 03, 2006 5:24 pm Post subject: mounting scopes straight

Hey guys,thought I would share a way that I devised to mount a scope with the crosshairs true.I always have a time of it trying to get the crosshairs PERFECTLY vertical and horizontal.I am a bit of a perfectionist and sometimes would spend hours loosening and tightening ring screws staring through scope till my eyes hurt trying to get it just right.I would often use the old trick holding rifle out at arms length trying to line vertical crosshair up with screws in buttplate. Using this principle I found a better way.
My 35 Whelen Rem 700 had its scope mounted a little off by a 18 year old that was a little too anxious to start shooting(me).After 13 years of looking at canted crosshairs it started to bug me enough to take action.It wasnt as simple as simply loosening screws and turning scope,I had used some PERMANENT thread locker and had to drill screws out of both rings and bases(I would not of had to remove bases but I wanted to switch to dual dovetail mounting). After going to all this trouble I was even more determined to mount scope back on straight. After doing some thinking I put my Harris bipod on rifle and rested butt of rifle on a pack of toilet paper to level it.After using a set of dial calipers to make sure buttpad screws were centered(told you I was a perfectionist!)I used a 3 foot level held through center of screws and adjusted bipod until rifle was perfectly vertical.I then looked through scope and lined up vertical crosshair with a line in paneling on the wall(after checking line on paneling with level to make sure it was perfectly vertical,of course). I then simply slowly tightened screws alternating between them making sure crosshairs stayed put until all screws were tight. I know they sell devices to help with this task but I doubt whether they would do a better job than this method.This method wont work with Weaver style rings with screws on only one side of ring as they rotate the scope as ring is tightened(very maddening),but this could be used to check alignment after tightening.

Blaine · Member Joined: Feb 24, 2005 Posts: 260 Location: Maine

Your method will certainly make sure the rifle stock is plumb the the vertical cross hair. But......what if the action screws are not exactly plumb to the stock. In other words, what if the action sets into the stock with a slight cant in the first place. You could end up with the stock butt plumb, the vertical cross hair plumb with the butt, but the action (and barrel) canted from them. The only things that need to be plumb to one another are the action and cross hairs. Where the stock (and the stock butt screws) fall is non-critical. A simple (and inexpensive) level bubble set is an easy way to be sure that the action and the scope cross hairs are plumb to one another.

You may be able to alter your approach slightly to achieve the results you are looking for. If you use your bipod and level the ACTION to your wall line (instead of the butt screws) you will achieve a better alignment. Perhaps by aligning the center of the tang with the center of the bolt might be a better alignment reference point than the butt screws. Just my opinion.

Blaine

roklok · Posted: Mon Jul 03, 2006 7:34 pm Post subject: Re: mounting scopes straight

You have a valid point Blaine but in my thinking unless you are using very high rings (I use low rings on all my rifles) the action would have to set in stock VERY crooked to be of any significance.My main concern is to have the crosshairs lined up with centerline of stock as the stock is my point of reference when shooting. In other words when I am handling and shouldering rifle I am concious of the stock not the action.This brings up another interesting point,not all rings and bases center scope perfectly over action and barrel. This could have same consequences at longer ranges as a tilted action.

Spacedone · Member Joined: Nov 04, 2005 Posts: 266 Location: missouri

i cant my crosshairs slightly on purpose. being left handed how i hold the gun cants the crosshairs so i cant my scope so when im holding the rifle it appears to be straight to my perpesctive/ lol

ripper007 · Member Joined: Mar 05, 2006 Posts: 199 Location: Colorado

I do not like looking threw a scope and seeing the cross hairs not straight.

I just mount the scope to the gun and lightly tighten it just enought to hold it in place.
I then hold the gun look threw the scope , makeing sure it is set where it comfortalbe to look threw. then see about how far I need to turn the scope to get the cross hairs straight.

I did spend alot of time useing a level one time to get a scope as perfect as possible. then realized , I just spent alot of time getting the scope level, where I could do about the same thing by just eye-balling it , getting it almost just as good. and it did not make it shoot any better.

so now, I just slap it on , do a few eye-balling adjustments to get it straight enough. then hit the rang to get it sighted in.

I do understand what your saying, and I do not dissagree at all. its not a waist of time if you enjoy doing it . that is what counts.

after reading your post , it did give me a good easy way to mount a scope. next time I need to do this. will surely give your suggestion a try.

Thanks.

PaulS · Posted: Thu Jul 06, 2006 12:15 am Post subject: Re: mounting scopes straight

For easy to use gear to mount your scope so the crosshairs are aligned mount your rifle in a rifle vise so that the scope and gun are aligned vertically. place a plumb line at the nearest distance you can see in the scope. Align the vise and gun to center the scope on the plumb line. turn the scope so that it's crosshairs align vertically with the line and lock it down. If you hold the gun to your shoulder and the crosshairs do not line up vertically then you are not holding the gun vertical. It is best to have the scope and barrel in vertical alignment so that the bullet does not move off bore center-line with distance. That way you only have to hold over or under when shooting out of your normal point-blank range (or change the elevation settings) and not have to remember that it is shooting to the right 1 inch for every 200 yards beyond 300 yards because the scope is mounted off to one side because you hold the gun canted at your shoulder.

This plumb line is easy for any handloader to make. Take one empty bottle-necked rifle case. Deprime the case. Tie a knot (a big knot) in one end of a four foot piece of string. Wax the other end of the string and thread it through the neck of the case and then through the primer flash-hole. Pull the string all the way until the knot stops it from coming through the flash-hole. Seat the heaviest pointed bullet that you have in the case. You now have a plunb line with a true hunter's plumb bob at the end. I used a 3006 case that was to be retired and it worked so well my carpenter brother wanted one for his work. I used it to mount my scope, a sundial, a flag pole, and a table top for an umbrella where the hole in the table had to be vertical to a matching hole in the ground so the umbrella would be vertical when mounted.

Handloader · Posted: Thu Jul 06, 2006 8:03 am Post subject: Re: mounting scopes straight

At the shop where I work we mount scopes on a daily basis. While I appreciate the desire to have a perfectly aligned scope, what I observe is that the majority of shooters cant their rifle left or right. This is mildly frustration when effort has been expended to get the crosshairs aligned.

Sooooo, doing some tests at 300 yards I zeroed an 06 @ 200yds and then fired a five shot group at the 300 yard target for a baseline. Then I rotated the scope five degrees, then ten degrees and fired again. There was no discernable difference in point of impact. Same test with a 220 Swift produced the same results.

To get a good crosshair alignment, I first take the scope adjustments to zero windage/elevation. I use a windage adjustable base or scope mount whenever possible and try not to use the scope's windage adjustment. I prefer to shim for elevation and then use the scope's adjustments for fine tuning. Here's why . . . using the scope's adjustments realign the internal erector tube from being straight and parallel with the scope tube to being at vary degrees of being off center. This decreases slightly the light transmission and can degrade the image by increasing distortion. We pay premium dollars for premium scope advantages and it makes sense to maximize the scope performance. OK, let me get back to alignment when mounting . . .

If the scope adjustments are at ZERO and windage has been corrected via the base, then look back through the objective lense by holding the rifle by the barrel or by looking from the muzzle of the rifle back through the objective. Any horizontal misalignment will be obvious and easily corrected. Presto . . . instant horizontal alignment. Now the scope can be zeroed to bore either in actual shooting or by boresighting. Some adjustments will be needed and once done, then look back through the objective lense and see how the crosshairs have misaligned from the objective lense side -- that is the erector tube distortion previously mentioned.

Crackshot · Posted: Thu Jul 06, 2006 10:10 am Post subject: Re: mounting scopes straight

I too work in a gunshop and mounting scopes is as easy as the customer wants it to be...... I center the cross hair as best I can, and bore sight the scope....end of story.

roklok · Posted: Thu Jul 06, 2006 3:39 pm Post subject: Re: mounting scopes straight

PaulS,
Sounds like you use basically same method I used,really like your idea for a plumb bob,I will have to make one.

Handloader,
Interesting experiment,I am curious though in your tests after rotating scope did you hold the rifle straight with reticle canted or hold the reticle straight with rifle canted?

Handloader · Posted: Thu Jul 06, 2006 8:41 pm Post subject: Re: mounting scopes straight

rokloK: the rifles were set straight using front and rear rests for all tests. The scopes were rotated a measured 5 and then 10 degrees. IOW the rifle position remained the same.

I'll be doing a similar test with a 45-70, 416 Rigby and 458 Lott next Monday in Prescott, only zeroed in both cases at 100yds and tested at 200yds with three shot groups.