To the best of my knowledge, the M21 300 Win Mag is available with a 24" barrel.
I have a couple of M21's...
308 Win has a 22" barrel
375 H&H Mag has a 24" barrel.
I thought so. I just bought one on Gunbroker but the description said a 22" barrel. I called the guy and he remeasured and said it was 24". Thanks for the reply.
Congratulations on the M21. They are shooters
In addition to mine below, my buddy (brinky72) has one in 300 Win Mag. His also shoots .5 MOA.
You are going to enjoy your M21.
