Given that duration of the throwing animation is nearly as long as the stun and damage minimal is don't see the problem.
Bundle or rifle grenade would like a word though. It's a very useful ability in tandem with those, which is fine, but it shouldn't be nondoc especially considering ost already has the best mg in the game at t0 so it's not exactly hurting for ways to restrict enemy infantry movement.
It is totally usable. Usable, not great. I would rather have a 4 man maxim than a vickers. It is still worth stealing the maxim obviously, it's just mediocre instead of being great. Soviets are paying the 260 manpower for the maxim to get a great team weapon. Enemies steal it for free and get a mediocre team weapon. Changes to performance are unnecessary.
Also to be fair, it's a gun from the 1880s being compared to weapons from the 1930s.
Finally someone who has as low an opinion of the vickers as I do
Sections shouldn't have that good moving DPS, and now they're OP again, but brits are still a weird crutchy gimmicky faction. Apparently we have learned nothing about faction balancing and won't actually fix any of the real problems with brits and instead are just giving them more OP line infantry.