Best way to grind weapons to +35 ?

What is the best way to grind up 13 star weapons to +35 ? some people recommend the collection file stuff so you can feed it to your weapon but it takes forever to complete the collection file imo

best way is to keep doing buster quests in the ranked you have a chance to drop then.

@Jamesmor To get collection files complete or ?

@AxelYuki the collection can only be completed with buster quest and buster quests can drop the weapons of the collection, so keep doing buster quest

if you mean actually plus'ing the weapon, then use sigma weapons, plus them to +10, and then use them as fodder for 13+ star weapons.

Best bet if collection folder for revolsio's is taking too long for you is to get a few sigma fodders and +10 them. then use those sigmas for your 13* rarity weapon.

@coldreactive Yeah thats what i meant since i didn't want to waste many grinders