REX-3 powder?

Have come up with about 5 pounds of REX-3 powder, 2 cans.
The guy I got the powder from said he was using it 'weight-for-weight' for Unique loads.
Example: 10.0 grs of Unique and the same weight of REX-3 seemed to him to give about the same velocity in rifle loads? He further added the REX-3 came to about 1 1/2 times the 'bulk' of the same weight of Unique...bulk for bulk.
Any comments on REX-2 compared to Unique use?
I'm thinking of 10.0 grs of Unique in .308 under the 110 gr Speer plinker bullet.
If used REX-3, and it provides about the same performance with 1 1/2 times the bulk, it would just fill the case better with bulk?
Any comments out there?
thank you for your time with all of this,
Bear

Hi Outsidebear, and welcome.

Just one question if I may ?
Who makes "Rex-3 and Rex-2" ?
I have never heard of them before.
I usually stick to Hodgen and Reloader _ for my rifle loads.

Al