I haven't really PVP much recently, but while testing on my test server last night just running around killing AI..

I noticed there is a huge delay between raising the weapon and ability of firing the weapon, probably an issue with tick rate, too fast of an action for the engine...?

If you try to aim and fire a weapon too quickly, the left mouse click does not register resulting in the weapon not firing. I don't think the gun matters for this issue.

I was testing on 1.27, but I've noticed this in the past on older builds, maybe this has returned, or my lack of PVP in the past few weeks has made me notice again.