Wildly inconsistent shots r700 .308

[J.flanagan]

I just came back from a very disappointing range day. I'm a pretty good shot, not amazing but I can regularly throw down half dollar and quarter size groups at 100yds.

Not today though. I just mounted a trijicon credo. Used Leupod mark 4 mount and rings. I was hoping to zero it in but couldn't get a group smaller than gallon paint can lid. 6 inches or so.

Can I just assume it's the glass or should I mount my old scope and try again? Other than shooter error, what could stop me from making any good groups at 100yds?

 

[Mag_7s]

Rifle shot well with other optic correct?

 

[J.flanagan]

Rifle shot well with other optic correct?

Yes, but not for about 8 months. It's been sitting lonely. I would imagine not a lot could change with the rifle sitting on my shelf.

 

[Mag_7s]

Did you have your parallax adjusted correctly?
Also, clearance between the scope bell and barrel shank?

 

[Flyjunky]

A Parallax issue isn't going to cause a 6" group at 100 yards.

If the rifle has shot fine in the past but now isn't then that says something in the new mount or scope isn't right. All the standard advice about checking torque, mounts, etc should be done. If that all looks good then remount your old scope and see how it shoots. If it shoots well with the old scope then it's either the new scope or mount problem.

 

[J.flanagan]

I've never had a scope with parallax adjustments, so I'm not sure. That being said, it clearly is marked for 100 yards and that's where I had it. There is between 1/8 and 1/4 of an inch between scope and barrel.

I should mention that I keep dirty guns. I don't clean each range day, only every few. Which, with my shooting schedule might mean it's only getting cleaned every couple years. I know I haven't clean this gun in at least 100 rounds/2 years. Would that contribute to my groups going from 1.5 inch to 6 inch? Is that too drastic to be blamed on a dirty bore.

 

[J.flanagan]

A Parallax issue isn't going to cause a 6" group at 100 yards.

If the rifle has shot fine in the past but now isn't then that says something in the new mount or scope isn't right. All the standard advice about checking torque, mounts, etc should be done. If that all looks good then remount your old scope and see how it shoots. If it shoots well with the old scope then it's either the new scope or mount problem.

In the past I've just hand torqued my scopes and mounts. This is the first one that I actually used a torque wrench on. I'll re check everything but I think it's torqued correctly.

 

[Mag_7s]

A Parallax issue isn't going to cause a 6" group at 100 yards.

If the rifle has shot fine in the past but now isn't then that says something in the new mount or scope isn't right. All the standard advice about checking torque, mounts, etc should be done. If that all looks good then remount your old scope and see how it shoots. If it shoots well with the old scope then it's either the new scope or mount problem.

You're right, that is pretty extreme for a parallax shift. Just trying to rule out the simple fixes first.

 

[Flyjunky]

In the past I've just hand torqued my scopes and mounts. This is the first one that I actually used a torque wrench on. I'll re check everything but I think it's torqued correctly.

Check everything in your mounting process and if that doesn't correct things definitely put on a known good scope. That should tell you what your problem is.

Something in your mount is either moving or your scope is bad.

 

[KenLee]

I've never had a scope with parallax adjustments, so I'm not sure. That being said, it clearly is marked for 100 yards and that's where I had it. There is between 1/8 and 1/4 of an inch between scope and barrel.

I should mention that I keep dirty guns. I don't clean each range day, only every few. Which, with my shooting schedule might mean it's only getting cleaned every couple years. I know I haven't clean this gun in at least 100 rounds/2 years. Would that contribute to my groups going from 1.5 inch to 6 inch? Is that too drastic to be blamed on a dirty bore.

Dirty bore won't make anywhere near that much difference unless your prior ammo was polluted with corrosive powder, then the gun left sitting for that 8 months.
Just a FYI, the stated range on parallax dial is just a suggestion. You adjust by what you see while in the scope.
No paralax being off won't cause a 4.5 inch increase in group size at 100 yards. MAYBE 0.25 inch

 

[SDHNTR]

this same gun shot better before with a different scope and mounts? Same ammo?

If yes, Something is goofed up with that scope and or mounts. Strip it down. Clean and degrease all screws and screw holes, rings and scope tube. Clean the rifle thoroughly too. Start over.

 

[davsco]

i'd clean the gun. maybe a little rust from sitting idle? check the crown, hoping it didn't get damaged.

i'd throw the old scope back on and make sure everything is tight, base/rings included.