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Rifle Scopes Lapping an AI one piece scope mount?

armorerr

Private
Full Member
Minuteman
Dec 22, 2008
12
0
Pittsburgh, PA
From what I can find via the search function, it sounds like the consensus is that any high quality rings or one-piece mount will not need to be lapped? I am assuming an AI mount would qualify but as I am looking for an S&B PMII 5-25x56 to put in the mount I want to make sure. I've never lapped rings before, and I don't tend to sell my gear, but I've also never dropped that kind of coin on glass before so I want to make sure I don't mess it up!

Thanks!
 
Re: Lapping an AI one piece scope mount?

When I dropped my PH into my AI ring mount it was like it was glued in place. The mating seemed perfect between the two -complete contact. Hopefully you'll find the same results with your combo.
 
Re: Lapping an AI one piece scope mount?

No need to lap.... Lapping is an exercise in futility and needed only to cover poor gunsmithing when installing bases (usually two piece) or poor quality rings. Either is a big NO NO as a scope alignment will be the least of your worries...
 
Re: Lapping an AI one piece scope mount?

It depends on what guns rail you are mounting it on.
If it's a lousy gun, with a crocked rail , lapping is defintiely a good thing.
If it's a good rail, such it is if it's on an AI, there is likely no reason for lapping.

On the other hand, it's better to lap one mount to much, than one mount to little........

Håkan
 
Re: Lapping an AI one piece scope mount?

Whether or not you want to lap is really up to you and there are opinions everywhere, but I like to lap all of my rings/mounts. I have yet to see a perfectly straight pair of rings from any manufacturer on any weapon, so I like to lap.

I lapped my AI dovetail mount:

AWP005%20048.JPG


My AI dovetail mount is the older style that is machined rather than cast and the lower ring halves were purportedly line-bored. However, you can see the forward lower ring half was not straight and was pointing slightly left. I don't know if the base warped after the material between the rings was removed or what. But the forward ring was pointing left.

Close-up of the forward lower ring half:

AWP005%20051.JPG


This misalignment was very small and I probably would have been fine without lapping. But I lapped anyway.

I've seen some newer AI mounts with the base portion investment cast rather than machined. On these bases, the lower ring halves were not even at all and you could see and feel depressions/concavity where the material shrank during casting. I would definitely lap these.

That's just me. Other people say not to lap aluminum because the lapping compound will embed in the alumunim. I haven't experienced this issue.