Charge Difference between Lapua and Hornady brass.

[myrifle]

My Lapua brass is toast after 12-13x and I'm looking at a 2 day match. I've been using Shooters World Precision in Lapua brass with a 123 grain Scenar and my powder supply is also very low. I do have some Hornady brass to switch over too and really need to conserve the powder

Question for those who have gone between the two types of brass holding everything else the same: what was your powder differential?

I do have my own guess, opinion, etc. but am interested in real world experience.

Buying new Lapua brass isn't an option even if it could be found (need to fireform, etc.)

With my starline, ppu and hornady brass.

Ppu averages .4 tenths less then starline
Hornady averages 4 tenths less then starline.