Borrow scope lapping tool???

[Spyder]

Dykem would be a much better plan than plastigage. Or a sharpie.

[sigstroker]

Yeah, plastigage needs to be compressed. Installing one screw on a rail probably wouldn't compress it enough to tell you anything.

Plastigage is an automotive tool designed to be a cheap way to tell you if you have enough clearance in bearings. All of this scope mounting discussion concerns things that should have no clearance at all.

[smoothy8500]

In doing a fair bit of research, it appears that placing rings too close to the turret body and over-torquing the rings creates greater issues that lapping can't fix. Squeezing the tube close to the turrets causes binding of the erector assembly or parallax adjustment.

Lapping rings may not improve fit, but it can't hurt. But, if the scope is not correctly mounted, lapping didn't help a bit.

[Ramsh00ter]

I lap all steel rings! Does it do any good, I don't know. But it eliminates the possibility. Shooting to me has a certain about of head games to it, so eliminating every variable I can just helps my head.

Got into a debate with a Leupold tech about lapping rings when I asked if they could supply a 34mm lapping bar. They tried to tell me their rings were near perfect and did not need lapping..... Really....

After having a 34mm bar ground from an old rail gun barrel, I lapped the 34mm Leupold rings, they were not round and had high spots.

I have lapping bars for 1" 30mm, & 34mm.

Pay the shipping and promise to return it, you can borrow it.

The 1" and 30mm were cheap to make, just order the bar stock from McMaster Carr and a handle. The 34mm was a different story, had to have one ground.

Drill a hole, tap, screw in the handle and you are ready to go.

I lap with four different compounds, 300 grit, 600 grit, 1200 grit, and Ultra Bright Tooth paste.

I can post a picture of what I made when I get home if you would like, they are easy.

PM me if you want to borrow mine.

[NiMiK]

If planning to use shims, Plastigage would make sense in determining the "gap" when installing the one-piece rail on the receiver. Bedding the rail with some sort of epoxy is easier though.

I agree with epoxy method. Lapping the rings is one thing but will the base make full contact on the receiver? That was one of my concerns before I decided to bed the scope base on my rifles.

[Spyder]

Lapping rings may not improve fit, but it can't hurt.

It most definitely can.

[hambam105]

I'd say the professionals know the purpose and ability to use a scope lap ring tool properly.
Therefore, my vote is to deploy a used HB electric grinder with a wheel no smaller than 8 or 9 inchs under low light conditions.

[shafferds]

Odds are you will do more damage than good. Put it together first with proper torque of screws and scope placement.

[jtv3062]

You paid big bucks for rings and then your going to ruin them? Bed the base and be done with it, that is if you bought quality base.

[Preston-CLB]

Please forgive my ignorance, but I have two questions:

1. What is 'Scope Lapping'?
2. Why is it done?

Thanks, gents,
-p

[mtenenhaus]

here's an example of one of the commercially available kits to lap riflescope rings.

https://www.brownells.com/gunsmith-tools-supplies/sight-scope-installation-tools/scope-alignment-rods/scope-ring-alignment-and-lapping-kit-prod126532.aspx

Basically it helps you both to align the rings so there's no undo pressure on the scope body...and it makes sure that the contact surfaces of the inner aspects of the rings are near perfectly inline and in contact with the scope body. In effect improving upon any mismatch or machining irregularities in the rifle mounting relationship.

Hope that helps.

[LynnJr]

Please forgive my ignorance, but I have two questions:

1. What is 'Scope Lapping'?
2. Why is it done?

Thanks, gents,
-p

It's a process that is supposed to allow for 100% contact between the scope rings and the scope tube.
It is done because the scope tube and the scope rings are machined parts and have tolerances.

[Preston-CLB]

Thanks for explanation, gents!
-P

[hambam105]

Who needs 100% scope body to scope rings contact, and who needs precision machined parts when 'Good-Enough' will do?

[ar15barrels]

I'm not going to knock lapping rings as a waste of time and effort, because there are situations when it may be the best option, but have you already eliminated all other variables causing the misalignment you're experiencing?

Do all mounting screw holes in the receiver align properly?

Are you using a one piece scope base or two piece?

If you're using a one piece scope rail, does it sit flush with no gaps?

Are you using name brand rings? (Beware of cheap, poorly machined rings)

Remember, you are combining several different systems, probably all manufactured in different facilities on different machines. All provide an opportunity for different tolerances between each other.

There's a good chance that if you eliminate all tolerance inconsistencies between the mating parts it may not be necessary to lap your rings.

The main reason to need tp lap rings is that the scope base does not fit correctly and the person has chosen to tighten it down to the reciever and twist the base instead of bedding the base to the reciever.
If you bed the base to the reciever so that the base is not twisted AND you use good quality rings, the scope will set in the rings and slide like it's on air bearings because everything is in alignment.
When the base is twisted or the rings are NOT square, then the scope tube binds and lapping will cut out the misalignment.

People don't realize that if you put the rings on different slots on the base after lapping that the rings are no longer straight to each other if the base is warped by being force fitted to the reciever.
This is not the case on a straight bedded base though.
You can move the rings and maintain alignment when the base is straight.

Lapping should be the last ditch effort to fix misalignment.
The FAR better method is to bed the base.