Bedding scopes bases

[MDFalco]

I bookmarked this video on bedding a while back when I was considering a long-range build: https://youtu.be/d6RopWI0-GE


What about lapping the rings as opposed to bedding the scope? https://youtu.be/fTIY9cZlpPs

[Meketrefe]

OK, so this has me interested and I'm a complete nube. I get the bedding the rail part with idea being to minimize any gaps, etc. between rail and receiver. Confused about 1. how to ensure scope is parallel to bore and 2. if scope is 100% parallel to bore but for argument's sake 1" above centerline of bore, doesn't that also mean you will never be perfectly aligned with target at any given range, after adjusting for bullet drop, etc? So a perfectly aligned scope with bore will shoot at let's say 100 yrds all day but will be missing mark at 200 yrds, etc. due to fact parallel lines will never cross, so if its on the mark at 100 it will bel necessarily below mark at 200, etc... Making any sense?

1) It is not that the scope has to be parallel to the bore because you might start with a canted mount forward in order to borrow some angle from the mount
so you will have more adjustment left going down. What you want is the vertical axis of the escope (elevation) to be true to the bore so when the elevation is adjusted the bore stays in that axis. For example if the bore and vertical axes are .05" misaligned at the bore they should be 0.05" misaligned at 100, 200 or 1000 yards that is discarded. Let try to put this into a picture. It is hard to see with words.

2) is explained in nr. one. you do not align the scope optical axis and rifle axis that converge at some point depending on the round / drop. What you align is the capability for the bore to stay in the veritical axis as you change elevation with the rifle well supported and leveled.. The bore axis is a reference as in the real life the actual shot is a parabola always dropping so think of it as a fine spray of water toy gun that can be adjusted in speed pressure and can go up and down. You want that to be a perfectly vertical plane that is true to the vertical axis of the scope and the stadia (cross-hairs) .

Once the vertical is true it is assumed windage is true.Then another issue is if the scope is actually true itself on its adjustment. Some budget ones are not so then you are screwed right there. Most folks might never make and actual adjustment and just holdover either Kentucky windage style or using a reference in the scope if there are any.

I will document this process for those who want to learn the variables at play here.

[Cgrutt]

Sort of following, thanks. Still not sure how you get the scope vertical axis aligned with vertical plane of bore. I thought that was what the elevation and windage adjustments accomplished. So for example, do you need to shim rings to get perfect alignment and how do you determine how much shim? Sorry for nube questions...

[Meketrefe]

no prob. let me make a picture for tomorrow otherwise it will take a lot longer to explain.

[masterswimmer]

I'm following to a point. Like CG, I'm not following how to align the bore & scopes vert axis. I too thought the scopes windage and elevation adjustments took care of all this.

What I've taken from this discussion is that the scopes initial zero can become 'dislodged' for lack of a better term, and bedding the scope eliminates that concern.

I think Mek or GS should plan a road trip to personally bed mine & CG's scope.

[Cgrutt]

If I'm following correctly and to put in simple terms its important to have centerline of scope aligned with bore looking through bore. So if when looking from top of scope down the centerline of both scope and bore should be on same plane. When looking through scope up and down(elevation) is not necessarily on same plane as bore. Is this the idea? If so I still don't get how you actually ensure this is the case....

[whauburger]

Here is some quick illustrations exaggerating why you would bed a scope base. One photo shows a perfect world of a perfect receiver and perfect scope base, you would tighten the base down and full contact would be made, no bedding necessary, and the rings would still be in a straight line. The second photo shows that since these are mass produced machine parts, say the receiver isn't perfectly squared as an example. If you tighten the front base screw, there would be a gap at rear. So you would need to bed the rear of the base so get a full contact AND aligned base. This will leave the rings in a straight line, giving the best surface contact on the scope tube and not bending the tube. If you did NOT bed this base and torqued down the back to get full contact picture how the base would then bend in an arch. Now imagine how the rings would be in an arch from the base being distorted. This will make the rings have uneven surface contact on the scope tube while also putting pressure and possibly bending the scope tube.

Lapping the rings is another step some people use to align the rings and to ensure full contact with the scope tube.

None of this is hard to accomplish in your home with minimal tools and know how.

Hope this helps some understand.

[whauburger]

Side note, if anyone in Orange County wants to bed a scope base or is unsure if they should and would like I can meet up and help out. Again it isn't difficult, the biggest thing is your are not going to bed the entire scope base, only where it is needed (ie front or back), and to make sure you allow the JB weld or bedding compound to cure fully.