Apex barrels on M&P 40 -> 9mm

Post by: wittmeba
Apex replacement barrel for an M&P .40 -> 9MM.

I'm trying to decipher the words about the two different replacement barrels for the M&P pistol.

- Drop-in fit but may require some minor customization and should be able to be performed by the user

- Gunsmith fit fit should be fitted by a gunsmith

What distinguishes a user from a gunsmith when there are only possible differences for fitting?

My thoughts are the gunsmith fitted may add additional accuracy that the drop-in may ...

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