Welcome to MGO's Internet Discussion Forums…Please Consider Becoming a Dues-Paying Member of the ORG…Click >>>>>HERE<<<<< for more info…………****DONATIONS**** can also be made toward MGO's Legal Defense Fund and/or MGO's Forums >>>>>HERE<<<<<

Firearms Legal Protection

Page 1 of 4 1234 LastLast
Results 1 to 10 of 33

Thread: Shimming scope?

  1. #1
    I am a Forum User
    Join Date
    Jan 2018
    Location
    Macomb
    Posts
    13

    Shimming scope?

    Just bought a 450 Bushmaster with a Leupold 3-9x40 with adjustable turret on top. I sighted in at 100 yards, then put the adjustable turret on top. The next shot I took was at 160yards, set the turret to 160, shot a group, and they were all about 6-8" high and to the right. Not happy about that part, but moving on..

    I noticed at home however that I can't turn the turret past 260yards. It just stops rotating at this point. I'm wondering if I didn't max out the adjustment on the scope and need to shim the front or back mount. But now my question is how much shim? I have access to all types of shim stock, but not sure if it's something as a little as .001" or .005" will do it. I have all the way up to .05" but figured that much has got to be overkill. So just wondering if anyone out there knows of an equation for shimming, so I don't have to waste ammo doing a trail and error. Thanks in advance everyone!

  2. #2
    MGO Member JDG's Avatar
    Join Date
    Aug 2008
    Location
    Battle Creek
    Posts
    8,231
    I would not shim a scope period. People, manufacturers, go through great lengths to keep the two mountings surfaces on the same plane(flat), clamping a scope down on a set of stepped rings, could bind up the scope, kink the tube. Did you torque the rings with a torque wrench? Over tighten a scope can make it bind up, most rings call for 15-20 in/lbs. If you go to a tapered 1 piece base, you are much better off, you need to keep the two rings on the same plane. Not sure of the ballistics on the 450 BM, but it would seem there would be enough elevation on the scope to dial in 300 yards, without going to a tapered base. I would mechanically zero the scope, see how far its off at 100 yards. Its not unheard of that the receiver is not true, throwing off your scope in the first place. I think Burris makes rings with tapered inserts, I would much rather go that route then shimming a ring.
    Last edited by JDG; 01-17-2018 at 06:36 AM.
    Active airport shooter

  3. #3
    I am a Forum User
    Join Date
    Jan 2018
    Location
    Macomb
    Posts
    13
    Thanks for the info. I actually had Randy's up in Bad Axe mount the scope and bore sight. So I'm sure it's torqued correctly. I called and asked them about this issue, and they said that my scopes elevation is probably maxed out and needs a shim. It would be a disappointment if I'd have to buy aftermarker accessories to make this scope work, but if that's the only option other than shimming, I might not have a choice

  4. #4
    MGO Member Ol` Joe's Avatar
    Join Date
    Jul 2005
    Location
    the dog house
    Posts
    10,661
    My understanding is the Leupold Randy sells is calibrated with the 450 in mind and if so should cover the full range of the turret markings with that cartridge. Try calling the scope manufacture and see what they recommend.
    "Saepe errans, numquam dubitans --Frequently in error, never in doubt".

    The trouble with the Internet is that it's replacing masturbation as a leisure activity. ~Patrick Murray

  5. #5
    I am a Forum User
    Join Date
    Apr 2013
    Location
    S.E. Michigan
    Posts
    3,831
    Did you set the scope to mechanical zero before starting your zero process? [if so.....] How far from MZ did you travel to get zerod at 100 yards?
    My first call would be the the scope mfg, then, if needed, based on their feedback, possibly a 20MOA base. I wouldn't play with shims.

  6. #6
    I am a Forum User
    Join Date
    Sep 2011
    Location
    Lansing
    Posts
    5,892
    Assuming you properly zeroed the rifle, then properly slipped the turrets, you've run out of elevation... which isn't surprising considering the scope you're using.

    The proper solution is a canted base or mount. If this is on a bolt action, a canted base is what you need to be looking for; 20moa should be sufficient. If this is on an AR, you need a canted mount; again, 20moa.

    Putting a shim under a ring or base, is never the "proper" way to do it. I'd be skeptical on everything that shop is doing, if they are advising a shim as the solution. It's 2018... not 1948.

  7. #7
    MGO Member Roundballer's Avatar
    Join Date
    Mar 2009
    Location
    I/C "Gateway to the Thumb" Lapeer County
    Posts
    22,562
    What model is the rifle that this scope is on?

    Does it have a picatinny rail?


    Life Member, NRA, Lapeer County Sportsmen's Club Disclaimer: I Am Not A Lawyer. Opinions expressed are not representative of any organization to which I may belong, and are solely mine. Any natural person or legal entity reading this post accepts all responsibility for any actions undertaken by that person or entity, based upon what they perceived was contained in this post, and shall hold harmless this poster, his antecedents, and descendants, in perpetuity.

  8. #8
    MGO Member JDG's Avatar
    Join Date
    Aug 2008
    Location
    Battle Creek
    Posts
    8,231
    After rereading your post, I would just set your zero at the range you expect to hunt. Get a ballistics chart for your caliber, and learn your hold over, or under. Adjustable turrets are nice for stationary targets, but not so much for hunting. Sounds like your turret is not matched to the scope adjustments. So you zeroed at 100, installed the turret to 100? twisted up to 160, grouped 6-8 high? If so, your turret does not match the adjustment. You might very well be at a 250 yard zero, when the turret says 160.
    Last edited by JDG; 01-17-2018 at 04:18 PM.
    Active airport shooter

  9. #9
    I am a Forum User
    Join Date
    Jan 2018
    Location
    Macomb
    Posts
    13
    Thanks everyone for all these replies. Glad I picked this site to ask these questions. My gun is a bolt action and it does have a picatinny rail. I actually don't know for sure if Randys MZ my scope or not. I would assume they would before mounting and bore sighting, but didn't physically see the guy mount it since he went in another room to do so. At the time I suppose I just trusted them without questioning what they were doing.

    "So you zeroed at 100, installed the turret to 100? twisted up to 160, grouped 6-8 high? If so, your turret does not match the adjustment" Yes, this is what happened. Does anyone know if these turrets are made my leupold? or is it something Randy's made specifically for the 450?

  10. #10
    I am a Forum User
    Join Date
    Sep 2011
    Location
    Lansing
    Posts
    5,892
    Quote Originally Posted by foste1cc View Post
    Thanks everyone for all these replies. Glad I picked this site to ask these questions. My gun is a bolt action and it does have a picatinny rail. I actually don't know for sure if Randys MZ my scope or not. I would assume they would before mounting and bore sighting, but didn't physically see the guy mount it since he went in another room to do so. At the time I suppose I just trusted them without questioning what they were doing.

    "So you zeroed at 100, installed the turret to 100? twisted up to 160, grouped 6-8 high? If so, your turret does not match the adjustment" Yes, this is what happened. Does anyone know if these turrets are made my leupold? or is it something Randy's made specifically for the 450?
    Let's start from square 1.

    What is the rifle model? What is the exact model scope you have? What is the model of base you have on your rifle? What are the rings?

    Full specs please, or model numbers would work.

    Then we can actually look at your best solution.

Page 1 of 4 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
only search Michigan Gun Owners Forums
MGO's Facebook MGO's Twitter