I honestly think (and I'm sure at least some other people agree with me) that the Magnus line needs a revamp. How about the line changes to this;
2* Pow Gun (Pure normal damage with a low chance of causing Weak Stun)
Splits at 3* to either Pierce or Normal damage
3* Magnum (Pure normal damage with a low chance of Moderate Stun)
3* Magnus (Pure pierce damage with low chance to cause Weak Stun on user and a medium chance to cause Strong Stun to monsters)
4* Mega Magnum (Pure normal damage with a low chance of Moderate Stun)
4* Mega Magnus (Pure pierce damage with a low chance to cause Weak Stun on user and a medium chance to cause Strong Stun to monsters)
5* Iron Slug (Pure normal damage with a good chance of Moderate Stun)
5* Callahan (Pure pierce damage with a good chance of causing Moderate Stun on user and a high chance of causing Strong stun on monsters)
The Iron Slug line has been buffed to do higher amounts of normal damage, not unlike the Troika lines normal damage.
The reason as to why the Magnus and Callahan line have a chance to cause stun on the user is due to the fact it is mentioned on the description of the Callahan to "leave it's user in a daze". The Callahan line is more specialized and is a very good Beast and Fiend counter because of piercing damage and high chances of Stun.
The Iron slug line is for all round use and a safe chance to cause a moderate amount of stun to monsters, while the Callahan line can stun monsters very easily at the cost of stunning it's user.
If you have anything to add to this idea please tell me so I can make this better! This line really needs some light shone on it.
Giving a weapon a 0 star craft branch is stupid. All you are doing is making rage crafting easier.