If I shim the rear scope ring with a piece of cut soda can, about how much Moa am I adding per piece? I would would like to use 4 tapered pieces in length. At 100 I do not have enough in my turrets
Shimming a scope with pieces of soda can.?
- Thread starter Redick
- Start date
I have not tried the soda can trick yet. I'd be interested in a simple answer like: 3.
But if you get anything sideways, the answer might be variable. And I'd be interested how long that idea holds if you ever move the scope between the rings.
Like the redneck idea. Skeptical of long term usage. I'd at least make sure all my soda can strips are uniform.. and be strict on that.
But if you get anything sideways, the answer might be variable. And I'd be interested how long that idea holds if you ever move the scope between the rings.
Like the redneck idea. Skeptical of long term usage. I'd at least make sure all my soda can strips are uniform.. and be strict on that.
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I shimmed my d48 using 3 pieces of soda can....it worked perfectly. That scope has been shimmed on that gun for well over 6,000 rounds. I believe you can gain approximately 1 MOA per .001" of shim. Soda can is about .004" if I recall correctly. So, APPROXIMATELY 4 MOA per shim?? (Partly depends on how far apart your rings are, etc)
However, I'd be careful of adding shims. If you tighten the rings, you can bend the scope or crush it due to the uneven slope placed on the scope.
Edit...I hope more precise and correct answers will follow...
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Shimming is really a BAD idea in general for several reasons ....
saddle effective diameter is reduced and tightening can far more easily crush the scope tube.
shimming one ring and not the other upsets the alignment ring to ring forcing the scope tube to tilt downward to contact the unshimmed mount
IF YOU SHIM ... only do so on a low recoil PCP and never on a Spring piston gun where TIGHT RINGS are required !!! keeping a scope from sliding during recoil with s shimmed ring you will must likely crush / dent the tube.
ADJUSTABLE MOUNTS are what you want to use ...... RWS dropper, SportsMatch or FX adjustables are the most popular
saddle effective diameter is reduced and tightening can far more easily crush the scope tube.
shimming one ring and not the other upsets the alignment ring to ring forcing the scope tube to tilt downward to contact the unshimmed mount
IF YOU SHIM ... only do so on a low recoil PCP and never on a Spring piston gun where TIGHT RINGS are required !!! keeping a scope from sliding during recoil with s shimmed ring you will must likely crush / dent the tube.
ADJUSTABLE MOUNTS are what you want to use ...... RWS dropper, SportsMatch or FX adjustables are the most popular
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That kind of risk in damaging the scope..I not worth it .. were are in the adjustable rings era .. get a pair..I know they are not sheep but after buying my first set I sold or give away every scope rings that were not adjustable..every scope I have is mounted now in adjustable rings...FX - or eagle vision..
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I have actually shimmed my scopes plenty of times before without any effects at all for extended periods of time. I usually use some electrical tape as the shim. Thank you for the replys
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Used to do the soda can trick all the time. I finally bought adjustable rings. Never had any scope damage. Unfortunately I don’t remember how much MOA I used to get, I used to just keep adding until I was there.
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Obviously, I've done it as well. So far, I am quite fortunate. I just always warn people about the potential consequences...
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A better material for shimming is plastic soda bottle. That plastic is about 0.2mm thick.
Now as for figuring how much the shim will move POI that calculation isnt hard to grok.
Suppose your rings are 10cm apart and you shim one piece of 0.2mm in one ring. You have changed the POI at 10cm by 0.2 mm. The law of proportional triangles takes over here.
At 1 meter the POI changes by 2mm. At 10 meters the POI changes by 2 cm and at 100 meters the POI changes by 20 cm.
One cm is about 2/5 of an inch. 10 cm is one mil at 100 meters.
Plastic grips the scope tube better and crushes easier than the tube. Don't over tighten anyway. That isn't necessary.
Now as for figuring how much the shim will move POI that calculation isnt hard to grok.
Suppose your rings are 10cm apart and you shim one piece of 0.2mm in one ring. You have changed the POI at 10cm by 0.2 mm. The law of proportional triangles takes over here.
At 1 meter the POI changes by 2mm. At 10 meters the POI changes by 2 cm and at 100 meters the POI changes by 20 cm.
One cm is about 2/5 of an inch. 10 cm is one mil at 100 meters.
Plastic grips the scope tube better and crushes easier than the tube. Don't over tighten anyway. That isn't necessary.
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You better off shimming the under portion where the rings grabs the rail or Picatinny. Loosen BOTH front and rear ring clamps first b4 shimming. You shim the back of the rear mount clamp not under scope tube saddle. Good to put a thinner shim under rear of the forward ring as well.
I would use drooper base or drooper or adjustable rings though. Damage can be unseen unnoticed not obvious to the naked eye that can limit scope function and have unseen irreversible scope tube damage from stress. Hope it's from a Lifetime no questions no BS Warranty (2B4U) scope company that has no questions asked especially if you aren't the original owner with proof of purchase receipt without registering within 30days of original purchase receipt such as Hawke MTC Optisan Falcon Mueller BSA Nikon and Vector and Discovery and so on (the list goes on) just to name a few off off the top of my head for sure UK based scope companies are smart to keep their investers happy in this case nixing warranty second hand or outright not lifetime like one year plus 4 more only with registration within 30 days of original purchase then option to extend another 4 more years after the first year. Beware buying used with these and other brands that won't have any warranty to the second or third owner.
Oh the Delta Optics and Kahles and March brands apply too that aren't Lifetime Warrantied so it's reasonable to be mindful of you aren't the original owner with proof of original receipt (2B4U?).
I would use drooper base or drooper or adjustable rings though. Damage can be unseen unnoticed not obvious to the naked eye that can limit scope function and have unseen irreversible scope tube damage from stress. Hope it's from a Lifetime no questions no BS Warranty (2B4U) scope company that has no questions asked especially if you aren't the original owner with proof of purchase receipt without registering within 30days of original purchase receipt such as Hawke MTC Optisan Falcon Mueller BSA Nikon and Vector and Discovery and so on (the list goes on) just to name a few off off the top of my head for sure UK based scope companies are smart to keep their investers happy in this case nixing warranty second hand or outright not lifetime like one year plus 4 more only with registration within 30 days of original purchase then option to extend another 4 more years after the first year. Beware buying used with these and other brands that won't have any warranty to the second or third owner.
Oh the Delta Optics and Kahles and March brands apply too that aren't Lifetime Warrantied so it's reasonable to be mindful of you aren't the original owner with proof of original receipt (2B4U?).
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I just buy the Hawke Mount inserts 25 MOA , Nothing to guess at just slip the front and rear inserts in and BOOM 25 moa, I keep my scope tight but do not use a cheater bar, LOL.
I think the mounts are like 14 bucks,,, Amazon prime has them...
Mike
I think the mounts are like 14 bucks,,, Amazon prime has them...
Mike
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I have shimmed in the rear ring with no issues. All PCP's. For springers I use the drooper mounts right out of the gate. P/W rail ones if you can get. If shimming, I use a piece of cut up tooth paste tube. .011" as I recall. It is soft, flexible, has a bit of grip (being plastic coated foil, I suppose). The Red Wolf sports a set of fully adjustable Sportsmatch rings.
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I’ve shimmed scopes. I doubt there is a gunsmith on the planet that would. Why when there are other options ? We have one piece scope mounts with MOA’s built in and FX no limit rings and the old Burris rings with the inserts. Sure lots of guys get away with it but you know it’s not the correct way.
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I started off shimming the scope inside the rings but wasn't entirely comfortable with it knowing that I was putting stress on the tube of the scope. So then I started doing like Odoyle and shimming the ring basses instead. After that I got adjustable rings which is all I use now.
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The scope on my.177 m48 is shimmed with a piece of feeler gauge. I have the chicom ZR knock off which has no cant to it. I've mounted my RWS 400s scope in it which I've used on this rifle since 1993. The knock off ZR has plastic inserts to bring it down to 1 inch from 30mm so it has enough give to not twerk the scope. I believe I used a.005 feeler gauge.
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Yes, 1 MOA per .001" is about right. With respect to all who warn against it, it is not a risky process if done in moderation (.020" is my comfort limit), and only reasonable torque is used on the ring halves. I know, it is in conflict with the geometry of the scope/mount assembly. I used the tactic regularly years ago with centerfire rifles, before we had adjustable rings. Some of those had substantial recoil, so the rings had to be very snug. I never damaged anything, but granted, it is not the preferred method.
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Often shimming the rear ring base with strips of a plastic canister.
Also skimming the inside of the ring sometimes with a couple strips of double sided tape. These are flexible and stabilize the scope without having to tighten too much. No scope damage yet.
Also skimming the inside of the ring sometimes with a couple strips of double sided tape. These are flexible and stabilize the scope without having to tighten too much. No scope damage yet.
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35mm camera film!
Look it up, it's what I use, work's perfect, it's tried and true from professionals, and old timers.
Donald
Look it up, it's what I use, work's perfect, it's tried and true from professionals, and old timers.
Donald
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In small bore silhouette days. A business card was used often ten thou. thick. I have used that on a lot of Leuphold and weaver scopes no problem. And they never moved. I was with a guy that shimmed his 375 HH with a beer can. I know. It was in use for 35 years.
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