In the past I have had some success with a punch and hammer to pound the rivet somewhat.this will tighten up any slop…if it is just a hack knife the resulting marks will just add caricature, but you can also grind/buff the marks out as well.
Note: it all depends on how the hole got worn in the first place, if the wear is lop sided this method is not the answer.all you will end up doing is permitly fixing the blade in what ever position you modified the pin…in this case you need to remill (drill) the holes and add a bigger pin (rivet). A lot of work just to use the tormac….
if you are just practicing try some of those little knives you find @the dollar store…
The edge can be a very large place to find one's self.The trick is to think small.