Problems zeroing rifle for two calibres

[jon15 14]

I have a Blaser R93 and two barrels a .243 and .308 I am shooting a 95gr .243 round and a 150gr .308 round, both are moderated with one jet z 30 cal which is proofed for both barrels, currently has a 8x56 swarovski scope mounted on saddleback mounts.

My problems start once I have the rifle zeroed for the .243 I then change barrels and am unable to get the .308 to shoot a group as the scope does not have enough cross hair movement, i.e. I can not move the cross hair up and across enough, if I shoot the .308 without the mod there is no problem as it only requires minimum movement to get a zero.

I have not made any changes to the rifle, mounts or eye relief distance yet as I wanted some advise first, would be very grateful for advise or to hear if anyone else has experienced a similar scenario. thanks Jon.

[SportingShooter 0]

Seems that the Moderator when put on the .308 barrel is moving the Zero a great deal.

 

Check the thread on the .308 and see if the Mod is sitting level and tight, clean the thread with some oil too. Then check the crown of the .308 barrel, for dents, no matter how small. This could throw it off too.

 

I cant see it being the mod as it shoots fine on the .243.

 

Hope this helps

 

SS

[mattydski 560]

The other thing to check is if you have one barrel fouling the woodwork, i.e not floating.

Matt

[jon15 14]

Will try both and let you know how i get on, thanks.

[dicehorn 38]

I have R93 in both 22.250 and 6.5x55

 

Interesting problem!!

 

As you are aware Blaser mounts are horribly expensive ( I'm told over £300) so perhaps buying another set and a decent scope dedicated to one or other of the barrels (like I have) may not be an option for you.

 

Blaser barrels float - end of story

 

Don't think it is the mod

 

I think the least expensive option you should try is to take off your scope from the mount - examine the lugs where the mounts fit and ensure they are totally free of dirt, also the receiving grooves on the barrel, and the area where the scope makes contact with the rings, then re mount the scope ensuring that this (so very) important procedure with the tightening of the screws is done to the letter - perhaps zero the 308 first.

 

If this makes no difference, then perhaps a shim should be fitted to the mount

 

That's about all I can suggest at no expense

 

HTH

 

Peter

[Vegeta 0]

Does the .308 shoot ok groups? I know they are off zero but are the rounds all shooting to the same place at least?

 

Have a similar problem with my brothers rifle.

 

I think dicehorn is on the money. Its a mount issue by the sounds of it.

 

I am not familiar with saddleback mounts so excuse me if this seems stupid. Do the bases have screws on both sides or just one?

 

http://www.youtube.com/watch?v=HF3LCwrN3HY

 

look at this video, you can see the guy uses the screws on the mount bases to effect the left/right (windage) of the scope, long before he goes near the windage turret on the scope. Its about 5 minutes in actually.

 

IF you don't have screws on both sides you may be looking at using a shim.

 

So if I were you I'd take off the scope, adjust the turrets so that its perfectly centred. Put scope on the rifle and try to use the mounts as much as you can to get it on zero (left/right wise) and then use a few clicks of the turret for fine tuning.

 

I'd do it for the .308, then put on the .243 and see can you zero that.

 

That's what I'd do if it was me anyway.

Edited October 20, 2008 by Vegeta

[jon15 14]

Will try these suggestions and let you know how i get on after the weekend. Thanks.