yes that will work, I THINK.
also some people have used an oven, but approach it cautiously. you'd rather shrink them slowly or they may just shrivel up and "burn" (not necessarily catch on fire).
heck, i bet many heat sources could be used (torch, open fire etc) but something controlled and even is best.
try the hair dryer, just be careful how close you get the heat, likely use the high setting, rotate the handle and shrink evenly, abit at a time. you'll figure it out.
it's much like the electrical wire sleeves if you've ever used those for wire seal/repair.
also, i left it overhanging the butt a decent amount then trimmed it once shrunk to satisfaction.