I bought the aluminium one as my 1st mech
mod and ruined the 510 threads in 2 weeks! However it was because the floating pin was stuck and I hadn't screwed my atty right into the thread! Tapped out the pin cleaned the hole and reassembled and atty screwed right in and no further problems. So do what every veteran advises and fully clean, degrease and check for metal swarf before using any
fasttech purchase.
Also bought the Brass version as a replacement before repairing the Aluminium one. For some reason the Aluminium version hits harder than the Brass. Why?
But have to say for a novice I don,t think I could have bought 2 better mods.