Vertical stringing

P

Poc

Active member
I am loading 165PH in a 300 win mag. I have tried H1000, H4350, and H4831SC in several different charges and crimp tensions. I am getting consistent vertical stringing with very little horizontal deviation. In three shot groups it has ranged from 1-2” vertically. I usually try not to adjust my scope while working up a load because I want to see point of impact shifting. My groups have been about 3” high and 3” right so on my last group I decided to bring it closer to the bullseye. I was able to make the horizontal correction but found I could only get 2 clicks of adjustment down before the scope bottomed out. The scope is a ZEISS conquest with a 1” tube and has been on my rifle for a decade. There is no picatinny rail on this rifle and the rings are correct height with 1/8” clearance over the barrel.

Any suggestions before swapping out scopes to see if this has anything to do with the vertical stringing?
 
The vertical stringing likely has nothing to do with your scope so you have two problems. The vertical adjustment can be fixed with a 10 or 20 MOA rail. If you don't want to do that, change your zero range to say 200 yard and know that you are 1-1.5" high at 100. You could also shim the back scope mount...though that would not be my first choice.

Regardless of where you POI is currently, your vertical stringing problem can be a couple issues. What barrel contour do you have? Is your barrel heating up in the first couple shots causing the vertical stringing. Take it to 200 or 300 yards and see if the vertical stringing is exponential or consistent. If it is consistent, I would say it is you and or your rest? Are you using a rear bag? Is your front sling stud recoiling into your front rest? If it's exponential, I would argue you have not found a good load and need to find another node. Shoot it at further ranges and see if it opens up and that will tell you a lot.
 
Aside from the above mentioned, Ever have your rings lapped?

What rings do you have?

They torqued appropriately?

🍻
🥩🦌
 
Just curious what crimp tensions you have tried? Assuming all the above good points are met, changing crimp amount frequently changes the group size/shape for me?
 
I bought this Howa 300 win mag in 1992 when I was in college. It’s worn 3 different scopes, rings and bases over the years and now has a one piece base with dovetail rear adjustment screws. I knew I put blue thread locker on the rings and bases. After reading some of your replies and inspecting the rifle I found the windage screws had backed out and very loose. I do pray this was the problem! I hope to get back to the range to test it out and will update. Thanks again for everyone’s input!
 
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