Vertical stringing. What causes it?

[MCHOG]

I’ll look for it later. Unless someone can find Phil Velayo’s building a bridge video and post it.

 

[Jordanwickham]

Early on the OP said they ran a ladder test and took the higher charge that was still in the criteria for the verticle dispersion. Correct me if I'm wrong but my understanding of ladder test is that's not how it works. You wouldn't run a ladder test and take the highest load from the verticle dispersion criteria. You take the middle load that way if you have variations in anything ( powder charge drift, atmospheric, barrel heat, etc.) you are still ok since taking the middle load allows you to have some safety net either way. Taking the charge 42.8 just because you like the velocity and running with it doesn't make sense. 42.8 grains of H4350 is right near the top of max pressure in 6.5 CM. I don't know the H20 grains of the brass you are using but I know in Lapua in my chamber 42.8 grains is 20 PSI below max pressure 63000. That's not even taking the backtracked 59000 PSI max. Anyways that's alot of extra ranting but I would shoot a new ladder test and not load at the top of the verticle dispersion node. Load in the center. If you do a ladder run the top load then next week it's 15* hotter outside and you don't take time between shots your dope will go to hell in a hand basket. 15.7 SD is not a good place to start for 1000 yards at any point. Get down to less than 20 ES and your life will be much better. Depending on how many shots your Chrono test was done over. Assuming 5 shots a 15.7 SD is really bad you're looking at something around a 40 ES. At a 10 shot that could be somewhere around 65 ES.

 

[Dthomas3523]

Early on the OP said they ran a ladder test and took the higher charge that was still in the criteria for the verticle dispersion. Correct me if I'm wrong but my understanding of ladder test is that's not how it works. You wouldn't run a ladder test and take the highest load from the verticle dispersion criteria. You take the middle load that way if you have variations in anything ( powder charge drift, atmospheric, barrel heat, etc.) you are still ok since taking the middle load allows you to have some safety net either way. Taking the charge 42.8 just because you like the velocity and running with it doesn't make sense. 42.8 grains of H4350 is right near the top of max pressure in 6.5 CM. I don't know the H20 grains of the brass you are using but I know in Lapua in my chamber 42.8 grains is 20 PSI below max pressure 63000. That's not even taking the backtracked 59000 PSI max. Anyways that's alot of extra ranting but I would shoot a new ladder test and not load at the top of the verticle dispersion node. Load in the center. If you do a ladder run the top load then next week it's 15* hotter outside and you don't take time between shots your dope will go to hell in a hand basket. 15.7 SD is not a good place to start for 1000 yards at any point. Get down to less than 20 ES and your life will be much better. Depending on how many shots your Chrono test was done over. Assuming 5 shots a 15.7 SD is really bad you're looking at something around a 40 ES. At a 10 shot that could be somewhere around 65 ES.

This is one of the reasons I don’t use ladder tests. Too many things to attempt to look at.

Shooter error aside, you only have so many things that matter:

Muzzle velocity
BC
Consistency of bullets (variance in BC from bullet to bullet)

With a chrono you can find you powder node which keeps your velocity close enough across powder charges to accommodate changes. As well ensuring your ES is low enough that MV isn’t the problem if things fall apart down range.

With 100 yd group testing you can find your seating depth node which accommodates changes in throat erosion and velocity.

That leaves only Bullet consistency. Shoot at distance and if your groups open up (excluding shooter error), you have eliminated MV/powder charge and seating depth already. So, the only thing that is left to open groups up is inconsistent BC from bullet to bullet. You either need to sort or tip Bullets; or find a different brand.

You can do all this with chrono for powder and groups for seating depth. Without the need to decipher ladder tests or group tests.

 

[Jscb1b]

How do you adjust the rifle to be on target without using your rear hand to squeeze the bag?

I'm shooting off of a flat ridge down into a wash. I stacked my bags until I was lifting the but with my hand around an inch.