Gas/particle blowback and an extra-dirty gun are just some of the drawbacks to using a silencer. That said, delaying the gun's unlocking can improve those issues. You can try using the heaviest spring that will allow the gun to still function, and that will probably improve things at least a little bit.
Some people also tighten the gun's lockup by replacing parts like the slide lock, getting a tighter-fitting barrel, etc., but I doubt this makes a noticeable difference.
The biggest thing you can do is use different ammo: Instead of getting a stiffer recoil spring, you could use (or reload) low-pressure subsonic ammo that's just powerful enough to cycle the action.
On a side note, make sure the blowback is coming from the action of the gun and not the back of the can itself. If it's coming from action, that's normal. If it's coming out of the back of the can, you probably have a bad o-ring that needs replacement. The o-ring around the piston on my Octane fell apart and started sending stuff back in my face. At first I thought it was just an ammo issue. By the time I realized it was the o-ring, the can had misaligned enough from the o-ring failing that I had a baffle strike. Luckily it was a tiny one, it was more like a baffle scrape and not worth replacing the endcap over.
