Major problem with symbiotes users is their durability.
They can take bullets, even hits from rocket launchers and survive.
Damn during the end of Maximum Carnage Venom speedblitzed him with a super jump and smashed himself and Kasady into power generators and after the explosion he was still able to escape and reach a truck that took him outta from NY, Carnage was just unconscious.
If Punisher has got rocket launcher and a very powerful bomb maybe with nitro into it, they've got a chance, otherways they're f.u.ck.ed