New Lot of Brass with Old Powder Charge

[bill123]

I have a very reliable 308 load for 1000 yards and just bought a new lot of brass. How much load development should I expect to do? Can I get away with starting a grain light on the powder and increasing the charge until the new rounds chronograph like the old or is it more complicated than that?
Specs are:
Lapua brass neck turned to .014"
CCI BR2 primers
Berger 155.5 Fullbores
Varget 46.4 grains

 

[scottishkat]

I have a very reliable 308 load for 1000 yards and just bought a new lot of brass. How much load development should I expect to do? Can I get away with starting a grain light on the powder and increasing the charge until the new rounds chronograph like the old or is it more complicated than that?
Specs are:
Lapua brass neck turned to .014"
CCI BR2 primers
Berger 155.5 Fullbores
Varget 46.4 grains

Your current load is about 1.5 grains over max in the berger manual assuming the new brass is Lapua and the old had the same case capacity would be a no-no IMO. Have you weighed your new cases and or checked capacity i/e grains of water?

Whenever you change components you should drop back a grain, or more in the case of maximum loads. However if the case volume is the same there should not be a major issue.

I would not consider it a major issue to load a few 1gr under berger max of 44.6 and work up just to make sure there were no pressure signs. Do it with the heaviest cases by weight with your new batch would be my advice.

Good luck and shoot straight

Bob

 

[Mikecr]

If it's just a new lot of the same brand, I'd back off a tiny bit, fireform the new cases, and then verify my old load holds with the new lot. Same brand could be different pressure-wise but not so much that you couldn't tell within the first few shots & watching for pressure signs.

If you're changing brands, be more conservative. And yeah, you may have to re-develop with powder only.

Either way, you can't powder develop with new brass. It must be fireformed/stable, because once brass is fired it is never new again. The cartridge is adjusted by your chamber and dies. You're making it what it becomes.
This is what you develop with.

 

[bill123]

Thanks for replies. I'll work up from 1grain light. Bob. I realize that my load is hot by Berger standards but I worked up conservatively, have no pressure signs and an ES/sd of about 9/3. It's proven very precise out to 1000 yds.

 

[scottishkat]

Thanks for replies. I'll work up from 1grain light. Bob. I realize that my load is hot by Berger standards but I worked up conservatively, have no pressure signs and an ES/sd of about 9/3. It's proven very precise out to 1000 yds.

Understand completely Bill. I have gone over max on a few loads myself. As always for me it has been .3 to .5grains at a time. Anything near max with an ES of 9 looks real good to me.

Good luck and shoot straight

Bob