Range result differences when using different powder lots?

[artbosco]

I guess I'm fixing to find out in another week or so when I return to the range, just how that 2nd lot of H4350 powder is going to act!

It's never about how the powder is going to act [it just does its thing] but how the barrel is going to react [where the bullet exits during the vibration]. *The best place to shoot is just past a positive peak on the sine wave curve.

* Rifle Accuracy Facts by Harold R. Vaughn

 

[Michael Courtney]

I guess I'm fixing to find out in another week or so when I return to the range, just how that 2nd lot of H4350 powder is going to act!

It's never about how the powder is going to act [it just does its thing] but how the barrel is going to react [where the bullet exits during the vibration]. *The best place to shoot is just past a positive peak on the sine wave curve.

* Rifle Accuracy Facts by Harold R. Vaughn

I think you are likely right, but changing the muzzle velocity by 50-100 fps likely changes the barrel time and thus the point in the barrel vibration when the bullet exits.

 

[mikecr]

Outdoorsman has a good point.
There are many ways to match muzzle velocity, with different powders, different seating or neck tension, primers, etc.. But tune doesn't hold (can't be predicted) with this, as the pressure peak changes. So even if a different lot of the same powder changes MV by only an amount within previous ES anyway, tune can still be affected.

With any change at all, anything, tune can be affected.

 

[Michael Courtney]

Outdoorsman has a good point.
There are many ways to match muzzle velocity, with different powders, different seating or neck tension, primers, etc.. But tune doesn't hold (can't be predicted) with this, as the pressure peak changes. So even if a different lot of the same powder changes MV by only an amount within previous ES anyway, tune can still be affected.

With any change at all, anything, tune can be affected.

I agree, but I think the best bet not to affect tune is to replicate the previous muzzle velocity with the new lot of the same powder by making small adjustments.

This is one reason why it is helpful to keep loads a bit under max, it gives some room for adjustment with the new lot.

 

[artbosco]

I guess I'm fixing to find out in another week or so when I return to the range, just how that 2nd lot of H4350 powder is going to act!

It's never about how the powder is going to act [it just does its thing] but how the barrel is going to react [where the bullet exits during the vibration]. *The best place to shoot is just past a positive peak on the sine wave curve.

* Rifle Accuracy Facts by Harold R. Vaughn

I think you are likely right, but changing the muzzle velocity by 50-100 fps likely changes the barrel time and thus the point in the barrel vibration when the bullet exits.

You're absolutely correct. However, the barrel will tell you when you've got it right because bullets will be going through the same hole, given you're shooting in the same conditions. Have a set of wind flags?

 

[VaniB]

I guess I'm fixing to find out in another week or so when I return to the range, just how that 2nd lot of H4350 powder is going to act!

It's never about how the powder is going to act [it just does its thing] but how the barrel is going to react [where the bullet exits during the vibration]. *The best place to shoot is just past a positive peak on the sine wave curve.

* Rifle Accuracy Facts by Harold R. Vaughn

I think you are likely right, but changing the muzzle velocity by 50-100 fps likely changes the barrel time and thus the point in the barrel vibration when the bullet exits.

You're absolutely correct. However, the barrel will tell you when you've got it right because bullets will be going through the same hole, given you're shooting in the same conditions. Have a set of wind flags?

But of course......3 wind flags, a Jewel Trigger, adjusatable Hart Rest, 24X scope, and a carefully detailed notebook. You think I'm fooling around? ;D