The most important lesson puppies need to learn is bite inhibition. Google it. And here's a couple links from my favorite dog website.
Puppy Class And Biting, Mouthing Puppies | Dog Star Daily More On Bite Inhibition (Because It's So Important) | Dog Star Daily
These links and others I've seen suggest using the word "Ouch" when the puppy bites with any kind of pressure. You can even lick your wounds. Follow with praise, toys and/or treats when they stop or do it correctly.
I would lean against grabbing him by the scruff of his neck. Trying to teach non-aggression by using aggression is not something I've seen recommended.
Good luck!
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Mike ~ Doting Dad to Jillie, Harper, Molly, Cooper, Eddie (RIP), Lucy (RIP), Rusty (RIP) and Jack (RIP).
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