Snap setting can be tricky whether using a maul or a mallet.
The trick to setting snaps if finesse and proper snap selection.
Snap selection is easy the shank should not extend to far through the textile you are intending to set the snap in. .
Otherwise you will be forced to over strike coincidentally bending the shank leading to poor results.
Finesse is simple,Ttry to set your snap with a few soft blows rather than one powerful strike.
This way we attain a nice roll over rather than bending the shank.
Maul or mallet ? Its up to you. I tend to prefer a kick press but that opens up its own can of worms.
Best of luck,
Al Bane