I have used and killed deer with 87 gn. bullets out of the Mod. 20. I also used the 87 gn. bullet on chucks, before I began to reload. In a factory offering, I have not seen anything factory loaded, lighter bullet, than the 87 gner specifically for varmints. I believe that`s what the OP asked.
In my neck-of-the-woods, the 87 gner was used as a varmint load, the 100 for deer.
YMMV
