Regards .308 & 175 SMK case; capacity changes

[308sako]

When using Varget powder and Federal 210 primers then switching between Federal GMM brass and Winchester brass is there a "standard" adjustment to the charge for the case capacity differential?

Such as +/- several tenths of a grain to attain the same muzzle velocity?

 

[Aimsmall55]

Winchester holds a bit more powder. My suggestion is to weigh the shot federal brass... write down its weight...then fill it with water up to the case mouth, and that will give you a "close " powder capacity guess. Then do the same with the win brass. You'll likely find that the win brass is going to hold more. That's just because federal is so thick. I'd say win brass is going to have to hold at least .5 grains more. Again just a guesstimated guess

 

[wwrhodes91]

Dan Newberry has said .4gr

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

[Aimsmall55]

Dan Newberry has said .4gr

Sent from my SAMSUNG-SGH-I337 using Tapatalk

Damn, that was just a guess too!

 

[HobbyShooter]

I don't think his question has really been answered yet. He's wondering how much powder to add or subtract from his go to charge when changing to brass with a different case capacity.

I don't know of such a formula. Quickload could probably do that, or just chronograph your current load and then load up different powder charges in the new brass. Chrono the new loads until you reach your original muzzle velocity.

 

[wwrhodes91]

I don't think his question has really been answered yet. He's wondering how much powder to add or subtract from his go to charge when changing to brass with a different case capacity.

I don't know of such a formula. Quickload could probably do that, or just chronograph your current load and then load up different powder charges in the new brass. Chrono the new loads until you reach your original muzzle velocity.

That is exactly what I answered. Dan Newberry said that he subtracts .4 gr for Federal and .3 gr for Lapua.


Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

[HobbyShooter]

Lol. Sorry. My reading compression sucks today.

 

[wwrhodes91]

Lol. Sorry. My reading compression sucks today.

No worries

 

[Ultraman550]

I also think he said 10% when its LC brass so whatever charge you're looking at subtract that percentage. Good to know about the Federal and Lapua. Anybody know what it would be for Privi brass?

 

[308sako]

I don't think his question has really been answered yet. He's wondering how much powder to add or subtract from his go to charge when changing to brass with a different case capacity.

This is exactly correct


I don't know of such a formula. Quickload could probably do that, or just chronograph your current load and then load up different powder charges in the new brass.


I can try that, but have reservations using QL because the powder burning rate seems way off for my lot of Varget.



Chrono the new loads until you reach your original muzzle velocity.

This I believe is going to be the only sure way


I could believe that adding 4/10ths to the charge for the Winchester to accomplish the same muzzle velocity is possible, however that seems just a little much. I hope to chronograph some loads this Thursday.