Accuracy mystery

[wilssoon]

Yesterday at the range I shot a few very tight, one-inch groups at 50 yards. Moving out to 100 yards, I could not get shots to group at all. WIndage was right--but vertically, shots were hitting the top and bottom of the target six inches apart!!!! Checked scope and it was secure. I did not change position or do anything different other than change the distance.

Setup was: Savage Model 14 American Classic in 7mm-08; shooting Hornady Custom Lite 120-grain bullets.

Any theories welcome...

 

[gohring3006]

Definitely going to have to go thru the checklist of possible problems with the rifle and scope. Eliminate that, and go from there. The scope could be faulty, it can have severe parallax and still be clear.

 

[Trnelson]

At least you know the scope is tight, probably. Check the torque on the action screws and make sure something isn't against the barrel. If all that checks out ok, as gohring3006 mentioned your optic could be toast...

 

[lancetkenyon]

"Tight 1" groups at 50 yards"?
6" vertical dispersment @ 100 yards?

Even for a .22LR, that is not very good. For a 7-08.....terrible.

Barrel contact to stock
Action screws
Base screws
Ring screws
Bad scope
Bad parallax
Bad ammo
If shooting hot, barrel walking
Bad barrel
Loose barrel
Dirty/fouled barrel
Shooter error
Bad rest

 

[Rich Coyle]

Twist too slow?

 

[cdherman]

Twist too slow?

120 gr bullet in a 7mm, twist can hardly be too slow. Unless its some new fangled aluminum bullet (joking).....

 

[7stw]

I'm gonna follow gohring3006, on the parallax possibility. I had a rifle a few years ago, just about drive me batsh?t crazy!
I checked bedding, i checked this, I checked that. Finally, another member here suggested I swap scopes, Bingo.
What do you have to loose, hair?
Just a thought!
My .02 cents!

 

[Gwine]

Twist too slow?

This made me laugh.

 

[Rich Coyle]

This made me laugh.

I posted from experience. Fired Hornady 75 grain Amax in a 12" twist. There was a surveyor stake beside the 100 yard target board. The bullet went through the stake sideways.

 

[HARPERC]

....This made me laugh...

I had a custom barrel I ordered specifically with a 1-10" twist, never had cause to question it until bullets came along that needed 1-10" twist. For 30+ years I would have laughed at the suggestion it wasn't what was advertised. It wasn't quite as funny when I took the time to measure it myself.

Assumption is the mother of all foul ups. If you haven't measured it yourself, you're just guessing, and repeating what you've been told.

 

[cdherman]

Note that his issue was vertical axis distribution. I suspect something with the elevation erector in the scope is fubared.

One other really crazy thought. Are you sure its a 7mm-08? I think you can get a 7mm-08 to go bang in a .308. You would see very wide velocity and poor accuracy. Just a really crazy thought.....

 

[Gwine]

Trust me, there was no disrespect intended in my post.
After reading the list above your post, I had a chuckle when I saw 1 more possible problem.

 

[BEEMAN]

Yeah had a friend that couldn't figure out why he couldn't hit any deer. Turned out that shooting 270 out of a 30-06 isn't very accurate!!