I am putting 3/4 inch underlayment in an old convience store the floor was real bouncey.So I am beefing it up ,and nailing the 3/4″ BC Plywood about every 4″with 2 3/8 ring shanks.About 6000 nails .I have an older Senco framing nailer I bought about 1985 or so.It is real heavy.Something I noticed when I was framing a while back using a newer (light Gun)was the recoil went right to your elbo.That old gun may be heavy but it sure absorbs the recoil.
Anyway I was just reminded of that again last night.I am working through the night while the store is closed.After nailing the crap out of the floor i had no soreness in my Elbow.

Just an observation.Its been a couple of years since I have used a new gun ,I am not convinced lighter is always better.