To Lap or not to LAP.

[swimster]

To make a long story shorter. A buddy brought his .338 win mag out to test some loads. After shooting some huge groups at 100 yd. We checked his scope bases and rings for tightness. Plus all basic issues stock screws ETC. He called Leuplod about sending his scope in to have them check it. The Leopold tech said the would be glad to check it. Then the tech asked if the rings had been Lapped. Which they had when we Installed the scope. The tech told him that could be the problem and that lapping rings was old school. Your thoughts?

 

[JFrank]

Nonsense

 

[L.Sherm]

Bed the rings and forget about lapping.

 

[jelenko]

To make a long story shorter. A buddy brought his .338 win mag out to test some loads. After shooting some huge groups at 100 yd. We checked his scope bases and rings for tightness. Plus all basic issues stock screws ETC. He called Leuplod about sending his scope in to have them check it. The Leopold tech said the would be glad to check it. Then the tech asked if the rings had been Lapped. Which they had when we Installed the scope. The tech told him that could be the problem and that lapping rings was old school. Your thoughts?

I'm assuming the 'nonsense' comment was referring to more precise machining these days. That said, so what? Assume the rings are absolutely perfect when made - would lapping them lead to large groups?

 

[butchlambert]

I lap rings and bed the bases.

 

[JFrank]

I'm assuming the 'nonsense' comment was referring to more precise machining these days. That said, so what? Assume the rings are absolutely perfect when made - would lapping them lead to large groups?

My comment was in rebuttal to the Leupold tech’s suggestion that the huge groups at 100 yards could be the result of NOT lapping the rings.
I submit that the reason for huge groups ( whatever that means) is more likely the result of ammunition that isn’t tuned for that weapon coupled with poor recoil management of a very powerful rifle.
J

 

[jelenko]

My comment was in rebuttal to the Leupold tech’s suggestion that the huge groups at 100 yards could be the result of NOT lapping the rings.
I submit that the reason for huge groups ( whatever that means) is more likely the result of ammunition that isn’t tuned for that weapon coupled with poor recoil management of a very powerful rifle.
J

Exactly. Lapping the rings seems unlikely to cause the large groups.

 

[BoydAllen]

The only situation where lapping could cause a problem would be if size of the lapping bar was incorrect, or the lapping was done to the point where there was no gap between the ring caps and the bottom halves so that tightening the screws did not result in clamping of the rings on the scope. I have never run into either situation, and I have lapped a lot of rings without any problem. The assertion that lapping is an out of date procedure is totally incorrect. The easiest way to check a scope is to substitute one of known quality.

 

[Adam in WI]

The best machined rings mean diddly. The manufacturer of the mounts have no control over the quality of the rifle those mounts are screwed to. Lapping is cheap, easy insurance. But then again, I'm too lazy to learn how to bed rings.

 

[243Lapua]

To make a long story shorter. A buddy brought his .338 win mag out to test some loads. After shooting some huge groups at 100 yd. We checked his scope bases and rings for tightness. Plus all basic issues stock screws ETC. He called Leuplod about sending his scope in to have them check it. The Leopold tech said the would be glad to check it. Then the tech asked if the rings had been Lapped. Which they had when we Installed the scope. The tech told him that could be the problem and that lapping rings was old school. Your thoughts?

Have you seen the quality control on today's Leupold rings, they don't compare to the quality of the past. Lap them.

 

[L.Sherm]

I havent had a factory action yet I put a rail on that you screw one end done there isn't a gap in the other end between rail and action.
Anymore I bed the rail and rings both, really doesn't take any longer to bed the rings than lap them.
After you bed them theres 100% contact

 

[jelenko]

How do you 'unbed' them if you need to?

 

[rijndael]

I don't lap my rings.

When I torque the rings to the base, I do it with a lapping bar installed in the rings. I hope/think it helps keeps things well aligned during the tightening process. After they're torqued, I replace the lapping bar with my scope.

None of my scopes have ever gotten ring marks with this process.

 

[ebb]

Most rifles never have the rings lapped and shoot just fine. While it is a good practice it is not totally necessary.

 

[L.Sherm]

How do you 'unbed' them if you need to?

Why unbed the rings after they have been bedded to the scope?

 

[skeeljc]

Use a good PT rail. Make sure it fits the action, i.e. bed it or shim it. Buy GOOD rings. No lapping required.

 

[JEFFPPC]

I put a strip of masking tape on the bottom half of the ring and put them together. Never had an issue or a problem.. Win my share, always competitive, and not looking for busy work. Of course, I have no lapping tools for sell either.

 

[jelenko]

Why unbed the rings after they have been bedded to the scope?

I don't know - I want to change the rings? The rings don't fit right on another rifle I want to put them on?

 

[L.Sherm]

You should only be lightly skim bedding them, if you wanna switch up just scuff up and skim again.

 

[swimster]

Thanks for the replies. I didn't mean to say the lapping caused the large groups. Just hadn't herd lapping was out dated. I think recoil management is more of the problem. I'll have to give the bedding a try. Will sizing wax work for a release agent?