Snap Caps for 22LR tend to break around the rim, since they're usually plastic. Fully made 3D ones also crack around the rim and/or don't extract well. Instead of purchasing snap caps for my 22LR, I designed an insert for empty brass cases. Just put a drop of superglue into the case and you'll be all set.

I printed these upright and found that on my Ender 3 with glass plate bed, no brim or raft was necessary. I made these with Standard quality and settings including standard base and wall thickness, but with ZERO infill. The printer had no problem using Overture PLA, but of course your mileage may vary.

I suggest you use a bright color for the build so that you can tell at a glance that these are snapcaps and not live ammo.