.22 zero problem

[terrierman]

hi chaps,  I went out today to zero my photon rt scope .  scope zeroed no problem. and kept nice tight groups.  I then tried my other rifle with a vortex scope on and the grouping was terrible. both rifles are CZ  455 and the ammo was from the same batch.  I have had this problem with this rifle before.  zero fine then shots all over.  I'm not a bad shot and can usually put the shots in a 1" circle.  any ideas ?     

 

[Moorlander]

Whats your ammo? , try a different one.

[terrierman]

the ammo is eley subs.   the rifle with the photon was shooting 1" groups and the scope is not too clear in the day.  the other rifle was shooting a bit wider with an occasional flyer 2" out .   ???   same ammo, same rifle.   one has SAK sm the other wildcat whisper.

[Andrew]

Not all .22LR like the same ammunition. Did you clean it before shooting?~Andrew

[ColinBR]

A few factors there. 

First as above, try different ammo, then try removing the moderator if that doesn't work, and then try a different scope, making sure all is correctly tightened. 

Other possibility with the 455 is check that the barrel clamping screws are tight along with the action screw. 

[visiter1]

try al screws 

[VarmLR]

Start with the "wiggle test" as someone once advised me many years back (a reference to diagnosing engine faults where before stripping things down you wiggle all the wires to check for loose connections!).

Check bedding screws are to correct torque, then check mounts, then check mod is tight.  If it is, remove the mod and check the crown of the rifle...any damage there?. I once cleaned my 77/22 Ruger which could shoot eley subs into an inch at 100 yds.  It doesn't any more....more like 3 inches on a good day.  I never clean it now...may take many rounds through before it does!  The wax coating on bullets protects the barrel from much fowling up. I occasionally run a patch or bore snake through it but that's all.  If none of that works, try different ammo.  Before you do, try swapping the scopes over...it's not inconceivable that the scope may have a faulty turret...stays on zero for a few but then goes off.

 

[ergid]

Hi, have you tried swapping the mods? 

Has the scope had a knock? 

Are you using optilock rings?

[andybrock]

Years ago I had exactly the same problem with a Brno 22 rimmy, turned out the bullets were clipping the baffles in the mod due to a really crap threading job on the barrel...... just something else to check!

[terrierman]

thanks for all the advice chaps.  I ended up taking everything to bits and gave it a good clean. then bedded the action and then zeroed it. that seemed to have done the job. grouping bang on at 60yrd.  went out in the evening and shot two rabbits at just over 100yrd and another at 88yrd.  just off out now to see if I can do it again. bloody things are all over at the moment.