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Thread: Scope base screw 1/4 turn loose and another 1/2 turn loose. Cause groups to open up?

  1. #1
    Boolit Master

    BigAlofPa.'s Avatar
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    Scope base screw 1/4 turn loose and another 1/2 turn loose. Cause groups to open up?

    Wasn't sure where to put this.

    Im having a heck of a time with groups opening up with my .223. I thought it was my new bullets im trying. Magtech brand. The higher velocity the more the spread. So today i took out some loads with Berry's and Mag tech. Same deal. I did have ring clamps getting loose before. That is normal from use. Remedy to that was some clear nail polish. When i got home i went over the whole gun. Checked free float with a dollar bill it was fine. Checked action screws all snug. Then i decided to take the scope off and check the mounts them selves. Back mount. One screw was loose 1/4 turn. And the front one screw was loose a 1/2 turn. So i re-mounted them with blue loc-tite.
    One round at a time.
    Member of the NRA,GOA and FAOC. Gun clubs Zerby rod and gun club. Keystone Fish and Game Association.

  2. #2
    Boolit Master
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    I'm sure someone will chime in to say that the action harmonics are off resulting in groups opening up.
    My opinion is that the groups are likely the same, your sight picture is the variable resulting in your groups from a loose optic.

    Sent from my Pixel 5 using Tapatalk

  3. #3
    Boolit Master
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    Mounts and then scopes are my first check when accuracy changes, anything loose in the mount, mount base, rings or scope can cause all kinds of strange troubles. Grouping 3her,2 there, might be something in loose in base, mounts or scope. Stock bedding can cause strange groups but anything to do with scope setups should be suspect. I use scopes on most of my rifles but when things get 'strange' they are the first suspects if stock screws are tight. I torque set most screws, particularly stock bolts and scope mounts/rings, most mounts, bases get locking compound too.

  4. #4
    Boolit Master
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    I'm going through this right now with my new air rifle. The scope that came with it was a piece of junk. I ordered a better scope but I didn't realize the objective was bigger. The scope rings that came with the ope have a set screw in the rear mount that acts as a stop to prevent the scope bases from sliding backwards. I had a new set of older rings for airguns that didn't have the set set screw. I got it close but the more I shot the more it seemed I was missing. I got back to it today I looked like the rear mount may have slid back. I decided to put my scope covers on, They didn't have enough clearance anymore. This is a better set of mounts 4 screws for each ring & 2 screws on each base. I mat just drill & tap for the set screw and lock-tite all the screws.

  5. #5
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    Winger Ed.'s Avatar
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    Quote Originally Posted by BigAlofPa. View Post
    So i re-mounted them with blue loc-tite.
    That's what I do on assembly.
    It works, and you can remove them if ya ever have to.

    Beware putting something together with the red locktite.
    --- That stuff is like herpes, its on there for life.
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  6. #6
    Boolit Master 444ttd's Avatar
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    purple locktite is the stuff to use.
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  7. #7
    Boolit Grand Master

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    Check the fit of the screw in the thread, dont bottom it out but just touch bottom and back out 1/2 turn there should be a little side to side but excessive may indicate a bad fit thats not providing the fit needed. Over and undersized threads will loosen much quicker do to lack of surface area. While they are good products and do a superb job Loctite isnt a cure all.

    If this is an AR type rifle I would also check buffer spring and buffer as the bolt and carrier will produce a reverse recoil impulse hitting at end of stroke, This is more common on ar 10s with the heavier bolt and carrier.

    Make sure when using a thread locker male and female threads are clean and dry. coat not only threads but the mating surfaces for the head also.

  8. #8
    Boolit Master

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    Took the rifle out this afternoon. Its a savage axis. It's doing well now. I been shooting it a lot since i joined the club with the long range shooting. Im going over all my rifles so i don't have any more headaches.
    One round at a time.
    Member of the NRA,GOA and FAOC. Gun clubs Zerby rod and gun club. Keystone Fish and Game Association.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check