After 10 years of using Nap thunder heads with great success I switched to Nap spitfire I shot a buck and never found Him My Dad shot Him over a month later On opener of gun season . That was enough for me I switched back to thunder heads and then when I bougth a new bow I could not get thunder heads to fly good So I tried MUzzy Mx 4 and have had excellent results with them. I know shot placement is critical but there are many Unknowns when hunting with a bow IMO fixed blades have my vote