My 7STW has a Kirby Allen brake.
My only varmint rifle without a brake is a 220 Rocket. Unlike my braked varminters (243AI, 22-250AI, 22-243), it's always been annoyingly difficult to see bullet strikes with this rifle.
The good news is that the Rocket's barrel is losing its accuracy, and the new barrel will definitely be fitted with a brake.
FWIW, I shot a brakeless sporter weight .338 (successfully) for years because I didn't know any better. Now that I've experienced rifles with muzzle brakes
, I'd recommend them for any centerfire rifle...well, maybe except a 22 Hornet.