Are you sure about the sprite offsets? Afaik the coordinates are not connection points, but offsets of the sprites. As far as I can tell the origin of the sprite seems to be the center, meaning if I put them all in the middle part, then there will still be spaces if the stock/barrel are bigger or smaller than the original ones. Gun rarity does not mean projectile type. It may affect projectile type, but a legendary sniper rifle can have one of several kinds of projectiles.