Is it necessary to lap a cantilever scope mount such as this? In fact, is it necessary to lap all scope mounts?  Thanks!

It would depend on who makes it and how it is made.  You can buy a scope alignment kit and check.

Not all scope rings would need it but some will.
I haven't lapped any scope rings I've used. 

It would depend on who makes it and how it is made.  You can buy a scope alignment kit and check.

Not all scope rings would need it but some will.
I haven't lapped any scope rings I've used.

Mahalo Ryan07!

Ryan is pretty much correct.  Usually misalignment is from independent mounts or rail misalignment in a non contiguous rail set up and generally the poor quality mounts are the most problematic.  The higher quality stuff will have less issues of alignment and higher quality machining of one piece units are generally pretty spot on. 

I lap all of my scope rings, even the high end stuff.  I had Talleys that were off by just a hair, but it was enough to flex the Leupold tube and lock up the power adjustment ring.  John Perreira lapped the rings in 15 minutes, the scope dropped right in and was almost perfectly boresighted.  I'm sold on lapping--even if the adjustment things show that the scope rings are lined up, proper lapping will keep your scope from shifting under recoil (always a good thing) and in general the rings won't leave any marks on the tube.

You pays your money and you makes your choices.  Lapping is money and time well spent.

I wish they had this kit earlier: http://www.midwayusa.com/product/816462/wheeler-engineering-scope-mounting-combo-kit-1-and-30mm
everything you need to check alignment and true up rings

I wish they had this kit earlier: http://www.midwayusa.com/product/816462/wheeler-engineering-scope-mounting-combo-kit-1-and-30mm
everything you need to check alignment and true up rings

I have this kit, but avoid midway.  I tried buying from them and they wanted almost $50 shipping and that was USPS priority!  I have amazon prime so I ordered it from Amazon and it shipped direct from Wheeler for free.  I will note that the Sinclair kit is better but a good bit more.  I don't do a lot of rings every week so no big deal.  I do notice that the better quality one piece CNC units really have way more than +75% contact front to rear and lapping is an afterthought.   

I have this kit, but avoid midway.  I tried buying from them and they wanted almost $50 shipping and that was USPS priority!  I have amazon prime so I ordered it from Amazon and it shipped direct from Wheeler for free.  I will note that the Sinclair kit is better but a good bit more.  I don't do a lot of rings every week so no big deal.  I do notice that the better quality one piece CNC units really have way more than +75% contact front to rear and lapping is an afterthought.

Thanks for the tip! I have Prime as well. $50 for shipping?! Ridonkulous! You'd expect delivery within hours for that price!

Mahalo for all your tips & advices.  On the otherhand I always check ebay first.  Get good deals and reasonable or free shipping.