Tightening the rivet on a pair of slip pliers

[cheb]

Is it possible? They're quite pleasant to use but the gap between the two halves is about half a millimetre. My first instinct is to batter at them with a big hammer but I'm concerned about spreading the rivet between the arms.

 

[Bullet2012]

How about clamp the two halves together with molegrips then “squeeze “ the rivet in a vice.

 

[brightspark]

gently tap the rivet with a ball pien hammer round the edges .the bottom picture one

 

[Agroshield]

How about clamp the two halves together...

...with a sheet of paper or tinfoil or coke can between the halves...

 

[Screwdriver]

See what you're saying but there's no way it will mushroom out like that unless you get it beyond red hot.

One thing I have learned about metalworking or forming is that even the lightest tap will make a change. So rather than really batter it, a few judicious blows on an anvil and you will be able to sneak up on a perfect fit.