Did any other fighters use a 300lbs punching bag?

That can depend on the weight of the fighter. I disagree a bit, a bag half a person weight can increase punching power, but for best results go with a weighted bang that is not so easy to move.

Who uses 300 pound bags today?

 

If you punch a smaller bag flying towards you, you have resistance right there.
You can definitely build power on a lighter heavybag.
Unless we're talking a bag so light that it wouldn't belong in a boxing gym.
You can let it swing left to right, and hit it head on with hooks.
That builds power. Or at the very least, it helps putting power into your punching form.

Bigger bags are definitely better for maximizing your power though.
And also helps you get better at punching with power in combinations.

 

I think you misspelled “an opinion.”

 

anyone who fought the russian monster.

 

I was the same. Hated someone holding the bag. Used to like a pretty heavy bag that had a bit of "give". It's a feel thing, I reckon?

 

3000lb bag is nothing to Saint Primo

 

Lmao

 

Rocky was a very strong guy for his relative low weight. A heavy bag of this weight can hurt your wrists if you hit it hard. He was built like a little Rock

 

Holyfield used to use 300lb tyres to practice butting.