Lagging during sniper match

Hello

I've noticed that something is wrong when I play sniper match (both s&d and tdm mode), despite having acceptable ping (around 60, stable), I miss a lot, rarely anyone is regging my damage, while I get lots of deaths- mostly after I hide behind a wall. It's obviously some strange lag, but it only appears during sniper matches, when I run with rifle, it's all ok. Can someone explain me what's going on? I tried different servers (UK1, UK4), I was rebooting my router, nothing helps.