I take a deep well socket and sand paper to mine..You can switch sockets to get basicly to
size you are after..I like to have mine floating enough to run a business card the full
length until it touchs the recoil lug...

That hot water trick is an old one..I have heard of that befor only with plastic stocks.
Only the tallked of using steam,such as you would when bending lumber...to each his own...