I've never had a problem with the adjustable ones that have 2 bands, you tighten it down around the piston with a square 'Allen' type wrench. Then once the piston is in, release the band by pressing a lever.

Just be sure to square up the compressor to the bore before pushing the piston in. I like to let the skirts hang below the ring compressor to square the piston to the bore, then press the compressor to square it up, and a rubber mallet handle to tap the piston down.