You are sorta wrong. Let me tell you about the parts involved with the release of the hammer.If I recall correctly (and I may be wrong here), in semi, a different part ensures the hammer doesn't drop until the bolt engages into battery. ...
So you FS2K owners without the forward sear, you have nothing to worry about, safety-wise.
In a semi-auto the "secondary sear" holds the hammer back after each shot, until the trigger is released, then the hammer slips of the secondary sear and the "main sear" holds the hammer until the trigger is pulled.
On an FS2K without a forward sear the secondary and main sears are the only parts controlling the release of the hammer. Unlike the forward sear these sears are not mechanically linked to the bolt in any way, so an out-of-battery release of the hammer IS possible.
Fortunately for those without the forward sear you can't pull the trigger fast enough to drop the hammer on the bolt as it's traveling into battery from the last shot. But if something jams the bolt open, or if the secondary sear fails, you could defiantly have a round going off out-of-battery.
I think a PS90 without a forward sear is more dangerous in this respect. In the FS2K the bolt mates into the barrel assembly, and this 1 inch sleeve would likely protect you from the heaviest piece of shrapnel- the bullet.
I don't exactly think that folks without the forward sear should be scared. For one, the bolt has to be mostly closed for the hammer to hit the firing pin. But 'mostly closed' is still out-of-battery, so you could definitely expect a serious jam or parts breaking. A weapon with its forward sear is not only a bit safer, it's also more reliable.[/quote]
Another thing to consider...
Correct me if I'm wrong, but it seems the extractor has to jump over the rim of the shell casing. It would seem that this isn't likely to happen until the bullet is seated into the chamber. If the bolt doesn't close completely, the extractor shouldn't jump over the case rim and would therefore create a gap in excess of the firing pin protrusion length. It seems technically unlikely, even without the safety sear that either a PS90 or FS2K would fire out of battery.