Yes, you should be able to run 100 grain bullets in a 1:7 no problem up to 3200-3300 fps. Due to RPMs they may perform more violently than at slower twist rates. That could be a good or bad thing but given 100 grain bullets and what they are meant to do on medium sized thin to medium skinned game that should be a good thing. A lot of times with guys seeing bullets blow up it's the super magnum class of cartridges and it's later in the shot string after x number of rounds. I probably wouldn't go any lighter than 100 in a 1:7 but every barrel is different so you'd have to test and see.