GT ores when broken with a regular pick return a broken ore (gt.meta.ore.broken):
https://i.imgur.com/DrFuhGg.png
You can instead make a silk touch pick (ie: Steel with Amber tips), and use that only on ores. Real power players use a Jackhammer in no-ore mode to remove stone and leave ore behind.
Using the silk touch pick, you get whole ores (gt.meta.ore.normal):
https://i.imgur.com/sTgcmUO.png
When you return to your base with your whole ores, instead of using the Crusher on them immediately like you do the broken ores, instead use a boomstick or dynamite on them.
https://i.imgur.com/0zNktWK.png
https://i.imgur.com/gZiMlzM.png
Boomsticks break the ores open with Fortune 3, while dynamite has Fortune 5!
I make a 3x3x3 cube of ore, with the center hollow for the boomstick. I leave one block out so I can access the hole. Then I insert the boomstick, ignite the boomstick, and rapidly place an ore block to cover it. The blast is exactly 3x3x3 so there’s little danger standing outside it.
https://i.imgur.com/8JZzK6z.png
BOOM
https://i.imgur.com/dtbr31E.png
I turned 26 whole Galena ore into 51 raw galena ore.
https://i.imgur.com/xG7X2O3.png
Crushing 26 broken Galena ore (not silk/boom) with the crusher yields only 52 crushed galena ore to be washed and smelted. That’s just doubled from the crusher.
Crushing the 51 raw Galena ore resulting from the silk touch and boomstick process results in 102 crushed galena ore. That’s doubled, but the fortune 3 already multiplied our raw ore from 26 to 51!
TLDR: Use a silk touch pick to break out GT ores, then use dynamite to double them before doubling again in the Crusher.
EDIT: I was just testing in creative now, and got 68 raw galena ore from a boomstick on the 26 ore. Clearly there’s a variable rate of return, but that will become 136 crushed galena ore!
I did the same with dynamite, and got 98 on my first try. Dynamite has fortune 5, so the output will vary.
I couldn’t find any solid docs on Fortune 3 vs Fortune 5 in % return. Perhaps someone can share.
EDIT2: Trying to give better numbers. I just tested 1 stack (64 ore), and received 2 stacks + 47 or 175 raw ores from using boomsticks. That’s 2.7x ores from boomsticking a silk touch ore. Next up, double that in a crusher.That’s 5.46x total output.