Does lapping scope rings assure scope alignment and improve group size?

[Cassidy]

Looking over the various scope rings available for my 30 mm scope (I'm looking to buy a set for my Rem XCR 700 Compact 308), there is quite wide range of prices. My understanding is the more expensive rings are more likely to be properly aligned for the scope (with less/no scope distortion) than less expensive rings, but I do not know if this is actually true; i.e., I am unsure if the more expensive rings actually assure scope alignment and improve POI group size. If lapping all scope rings assures scope alignment and improves group size, then why not buy the less expensive rings and lap them rather than buy the more expensive rings. Does scope ring lapping improve POI group size; are there any data out there?

 

[Rem6br]

Cassidy,
Lapping scope rings insures no distortion on the scope tube and improves holding power of the rings this in turn should help in maintaining zero.
Does it improve accuracy? Well it has to help to some degree just by insuring
the scope tube is not distorted and doesn't move and plus it cuts down on ring marks on the scope tube

 

[fredhorace77]

Looking over the various scope rings available for my 30 mm scope (I'm looking to buy a set for my Rem XCR 700 Compact 308), there is quite wide range of prices. My understanding is the more expensive rings are more likely to be properly aligned for the scope (with less/no scope distortion) than less expensive rings, but I do not know if this is actually true; i.e., I am unsure if the more expensive rings actually assure scope alignment and improve POI group size. If lapping all scope rings assures scope alignment and improves group size, then why not buy the less expensive rings and lap them rather than buy the more expensive rings. Does scope ring lapping improve POI group size; are there any data out there?

Doesnt matter what rings you buy if your scope bases are not perfectly squared...then you also have to worry if the base holes drilled into the receiver are square and aligned...Your left with lapping or buying Burris Sign.Zee rings

 

[GSPV]

No.

It might help. It might not.

One thing to consider right away...is the scope itself straight?

I bed my scopes after a little lapping because I've never seen a scope that was straight.

YMMV

 

[Cassidy]

GSPV - how do you determine if the scope itself is straight?

 

[GSPV]

The same way that you find runout for a loaded round. Just longer.

 

[Cassidy]

Greg - what do you mean by the term "runout"? I have no clue how to determine if my scope is straight.

 

[GSPV]

Give me a couple of minutes...

 

[BoydAllen]

The fellow that I used to work for, has a much bigger rifle and scope budget than I do, and since I was the one that introduced him to some of the finer points of rifle building, shooting and reloading, it fell to me to mount his scopes. Let me tell you, when you are mounting scopes that retail for more than 2,000, for the fellow that signs your check, you want to get it right the first time. The rings were top of the line, and the scope bases were integral or one piece. I used Kokopelli lapping bars and the compound that is furnished with them. The story is told when you take a few strokes with the charged bar, and then look at the cutting pattern in the bottom halves of the rings. In every case, the fit was improved by lapping. None of this guarantees the alignment of the scope, that is determined by the alignment of the action's base mounting holes. The actions that we were working with were all custom and pretty well aligned, based on the amount of adjustment it took to zero the scopes, starting with the reticules centered. I have also bedded rings with good results. The easiest solution to date, when weight is not critical is to combine a Weaver spec. base or bases, with Burris Signature Zee rings. With these rings and the proper pairs of offset inserts, minor miracles can be accomplished. I have a Savage rifle that required .020 offset inserts, installed with the offsets aligned horizontally, with the front in the opposite direction from the back, to center the scope on the action. The combination worked very well, bringing the scope very close to perfect alignment, with no lapping, bedding or any sort of metal work. Obviously actions should not be this far off, but this one is, and I was able to fully compensate for the misalignment. Lots of fellows are told that you can buy the expensive stuff and just bolt things together. If you are dealing with factory actions this is complete BS, and even with custom actions, it is better to either lap or bed. As to whether you will see any difference on the target, it is hard to say. That depends on how correct other details are, including the rifle, scope, loads, and the shooter.

 

[GSPV]

Ok,

The jig below is built to show total indicated runout of a loaded round.

You spin the round and the dial indicator rides the bullet and shows how out of alignment the round is. Kinda. Close enough for govt work.

So, you use the same idea to see how out of alignment the scope is. You ride one end of the scope on a set of bearings like the butt end of the round below and put a dial indicator to the other end.

...or, you can just assume that the scope isn't straight. If it is, it's a miracle and we don't generally count on miracles.

That's why so many people use Burris Signature Z rings or bed in their scopes.

I do NOT claim that it cures any problem. But, it eliminates a potential problem and that is worth a lot to me.

 

[savagedasher]

I will bet you the scopes have more run out and are not as straight as a gun barrel.
Having said that lapping really does nothing. Bedding or ZEE rings is the only answer.
With ZEE rings you can change from one gun to another. Good Shooting Larry

 

[GSPV]

Where is Al Nyhus when you need him? Out hot-ridding, I bet!

 

[Alex Wheeler]

I lap and then bed all my scopes. In every case, including custom actions the fit of the scope to ring was improved by lapping, and perfected with bedding. If you don't want to bed, lapping will improve the fit. Just don't over do it. Scopes may not be perfectly straight, but they are a lot straighter than the rings on a un-lapped set up.

 

[Cassidy]

Greg - thanks for all the explanation - it helped. Got to read Boyd's and the other's feedback now.

 

[Cassidy]

Thanks for the great info! How can I tell if the base mounting screws are aligned?

 

[Lapua40X]

Does scope ring lapping improve POI group size;

No. Group size is a factor of consistency (shooter consistency, load consistency, etc.) not scope alignment. A scope can be out of alignment and, as long as it's tied down securely and the adjustments are reliably secure, the rifle can still produce a respectable "group size", regardless of where on the target it's printing.
Not to say that you shouldn't lap the rings. That's an individual choice.
I've never lapped rings. Just used a trued solid steel bar to align them and hooked 'em up. But my scope guru has convinced me that Burris "Z" rings is the way to go and he has the experience to prove it so that's how I set up today.

http://forum.accurateshooter.com/index.php?topic=3823491.0;topicseen

http://www.sinclairintl.com/optics/rings-bases/scope-bases/davidson-bases-for-kelbly-rings-prod34801.aspx

 

[seb]

I don't think you need lapping or bedding with properly made rings & base.
seb.

 

[BigDMT]

I never thought to bed my scope rings. I always just lap them then wrap the body of the scope under the rings with hockey tape. My own quicker version of bedding to get the same effect I guess...

Might have to try the bedding method though. You fellas using Devcon Steel Puddy for rings too? Or would something a little softer like Devcon Steel Epoxy or JB Weld work better?

 

[GSPV]

I use JB Weld.

If I am using Redfield-type bases and rings...and my Savagd is drilled so out-of-whack that I do...I use a long alignment bar to get them aligned with the barrel.

On my custom actions, I use Kelbly Davidson-style bases and rings on the Kelbly/Stolle action and Borden Davidson bases and Harrell's rings on the Borden actions.

I lap then just to the point that they show near 100% contact on the bottom rings, clean them thoroughly, then bed them in JB Weld.

Why go to the trouble? Even if the mounting holes are straight. Even if the bases are straight. Even if the rings are straight. The scope is likely not straight. The way that they are made makes it hard to get the front and back halves aligned.

Too many times, I've put a high-dollar scope on my jig, put the dial indicator to it and found that it was about as straight as a banana.

Now, clamp that in the assumed-to-be straight bases and rings and you have stress. If you pillar/epoxy bed to avoid stress on your action, does it not make sense to try to avoid it with your scope bedding?

 

[Raythemanroe]

I don't think you need lapping or bedding with properly made rings & base.
seb.

Didn't you make your own?