All guns are deadly.
For a number of years in the US, the most 'deadly' caliber - the one which caused the most deaths, was actually .22 LR.
I think that has now been surpassed by 9mm.
That said, a focus on the caliber, or the type really loses focus on the actual cause of things.
A car doesn't drive itself into a crowd on it's own. A gun doesn't load itself.
A person is the operator in both cases, and it's the operator that the focus must be on.
We've come 35+ years down the trace since Gamil Gharby shot up a school in Montreal, and there has not been a single law proposed, nor put on the books which would have prevented it.
It is impossible to write law after law after regulation after OIC for 35 years, and continually miss the mark unless it's deliberate.
In truth, politicians don't seem to want to fix the actual problem...they just want the political gain/profit from using firearms as a wedge issue every election.
All we are is pawns in their game.