CAN YOU SHIM A SCOPE

[Evelio Mc Donald]

I received 4 new Weaver scopes, 2 24X and 2 36X > I rarely read instructions on scopes, but was curios about the total minutes of elevation between the 24X and the 36X and lo and behold, there is 3 full paragrafs about shimming a scope.
I thought this was very interesting, specially coming from a scope manufacturer. A copy of the instructions will be posted by my friend Paul under Scopes and Rings.
Enjoy it.
Evelio.

[kevinbear]

I was always under the impression it was unacceptble because reducing the I.D. of the ring would distort the scope tube but if the rings were lapped after shimming would it be alright? It could be difficult because the shims would have to be epoxyed in place so they could be accurately lapped.
It seems like alot of trouble when the bases are easily shimmed and a simple lapping job afterwords.

[malinois]

Rings need not be lapped...Only need something like a business card an aluminum strip or such and thats it. The higher power scopes have a very narrow adjustment window....The shim will help to keep you in the center of the adjustment range.

[kevinbear]

Check this out, http://www.thefirearmblog.com/blog/2008 ... g-lapping/

[BlauBear]

Check this out, http://www.thefirearmblog.com/blog/2008 ... g-lapping/

They do make a powerful argument for lapping.

[kevinbear]

[quote="BlauBear"][quote="kevinbear"]Check this out, http://www.thefirearmblog.com/blog/2008 ... g-lapping/[/quote]
They do make a powerful argument for lapping.[/quote]
Regardless of scope mfg how many times have you heard this at a match, I have to go past my setting and come back to the setting or this scope doesn't seem like it's moving untill I tap on it or shoot it once ? Many, many times right? Most of those kinds of problems are a direct result of the stresses on the scope body by unlapped/untrue rings.

[BlauBear]

Regardless of scope mfg how many times have you heard this at a match, I have to go past my setting and come back to the setting or this scope doesn't seem like it's moving untill I tap on it or shoot it once ? Many, many times right? Most of those kinds of problems are a direct result of the stresses on the scope body by unlapped/untrue rings.

[malinois]

Having worked on a few scopes in my day, I can say one of the biggest scope killers is over tigtning of rings..If you kink up a scope tube you will defenetly harm its ability to adjust...there is not a whole lot of clearence between the tube and the erector inside and on the high mag scopes we use in silhouette it is a killer. lapping can help..but its not 100 % needed it just eliminates a variable and sure helps to not marr up our nice scopes too.

[BlauBear]

I'm learning that the point of equipment preparation is controlling variables.

[40inarow]

I've shimmed scopes for decades, did it like the Weaver instructions say. The main advantage is that you set the scope adjustments at the middle of the range and zero using shims so that your adjustments from chickens to rams are closest to middle range. Scope adjustments toward the end of range tend to be less repeatable. The Burris system using different inserts does the same thing. I've used both with perfect success.

I would recommed beer can shims over cokes due to the increased satisfaction in obtaining the shim material.

[old sparky]

Here while back I needed more elevation and was guided to shim my scope. It worked great and while talking with a leupold tech. about changing retcles. I was guided to the link below and told to look at #6 on the FAQ page. It seems leupold will even send you shims free of charge for their scope. I found that interesting.
Sparky


http://www.leupold.com/tactical/resources/faq/

[Evelio Mc Donald]

It looks like some of you folks are confusing the purpose of shimming and laping rings.
Lapping the rings once they are mounted on the action, all it does is to align each ring to each other, no relationship to the center of the bore what so ever. These is great as long as you never removed those rings from the action, once you remove them, for whatever reason, and put them back even in the same action, they will not be perfectly aligned again. I could see doing this on a benhrest rifle when you never make more than one minute correction in elevation or windage, but as far as I am concerned this is a waste of time.
The reason for shimming a scope in our game, where you may have to make anywhere from 10 to 15 minutes of elevation change during a match, is to be able to reach the maximum elevation required and still not be at the top or bottom of the adjustment range.
99 % of the time, the shim is required between the bottom of the rear ring, and the scope, if the problem is running out of windage, then it would be best to shim between the base of the rings, and the action, rather than in the bore of the rings.
REMEMBER, lapping rings, don't have anything to do with achiving the needed elevation requirements,
please do read the instructions from Weaver, and Leupold, they never mention a word about laping rings to correct running out of windage or elevation.
Evelio.

[kevinbear]

[quote="old sparky"]Here while back I needed more elevation and was guided to shim my scope. It worked great and while talking with a leupold tech. about changing retcles. I was guided to the link below and told to look at #6 on the FAQ page. It seems leupold will even send you shims free of charge for their scope. I found that interesting.
Sparky


http://www.leupold.com/tactical/resources/faq/[/quote]
If you read that carefully they suggest shimming the base not the scope, big difference.
On the subject of base shimming once one ring and base is elevated higher than the other{ring and base} the surfaces the scope rests on are no longer parallel hence the need for lapping.

[austin870a]

Many rings just drop right in with no lapping necessary. They are perfectly straight and elevated just right. Others do not depending on several factors including how straight your dovetail or base/rings were built at the factory. If there is any tension on the scope but I am zero'd and have no elevation issues I will lap the rings just to ensure there is no tension or torque on the scope. As others have said lapping and shimming are used to accomplish different goals.

If I believe I am going to have zero or elevation problems I will use Burris Signature rings with the inserts and adjust it perfectly. I can also change guns/scopes using the same rings and not worry about any alignment issues. These rings solve pretty much all elevation and scope damage issues. They also never leave ring marks that devalue your scope probably close to 20%. Many people strongly believe shimming puts undo stress on the scope and can cause damage and poor performance. I believe there is probably something to that but challenging to determine how much on an individual application.

[kevinbear]

What it comes down to is some people are more detail orientated that others, while some are selective about their concerns.
I could care less about fancy paint jobs or having the latest fad equipment instead focusing on making sure my equipment is in tune as well as my mental and physical performance. When my relay is called to the line or there's a shoot-off and I see people I'm shooting against tapping scope turrets trying to get there scope to settle in rest assured I just recieved a little boost of self confidence.