Hello! I’m a long term lurker but first time poster on this forum.

Recently purchased a 645 online. Took it out to the range today and found out the trigger in single action was ATROCIOUS. Reset is short but the wall feels like it is 15 pounds. Letting the trigger past the reset point is very gritty. Anyone have any suggestions? Double action is fine but single is just unusable. The rest of the gun is great, so I’d really like to fix this problem.