What kind of jam is this?
 

What do you call the kind of jam where the front of a round goes into the chamber but the bolt doesn't go forwards all the way? Is it just a failure to feed or is there a more specific name for it? I ask because I have noticed it happening a lot in the most recent series of Strike Back with their P226s and wanted to call it the correct thing. Here is an example of the kind of jam I am talking about:

http://www.imfdb.org/images/thumb/0/...S04E05_250.jpg

Also, it seems like this kind of jam disproportionately happen with guns in TV/movies, is it a side effect of being blank modified? My guesses are that it was either the blanks were more fragile without a bullet so could be warped out of shape meaning they don't feed correctly, the powder in blanks doesn't burn as cleanly or completely meaning there is a lot more fouling in the chamber, or the main spring is weaker in order to allow it to cycle blanks but doesn't always have enough force to chamber a round properly. Is any of this the case?

In the Army, we would call that a "failure to return to battery"

My guess would be fouling combined with the modified spring.

Yeah, it's out of battery.

Thanks. I was hoping that it had a nice snappy name like "partial feed", or something like that. I vaguely remember being taught that it was called a "failure to close" but can't really remember. "Failure to return to battery" is a bit long winded (as well as seeming pretty vague to me, as that could mean that the slide is anywhere between fully back and full forward, by any cause).

Also, is this type of jam relatively rare in live firing guns, as I don't recall it ever actually happening to me without deliberately doing it by riding the bolt/slide forward. However I keep my guns pretty clean and am an obsessive "forward assister" due to being taught on the SA80 platform where it is part of the loading and stoppage drills.

Just a general question, does the forward assist just ram the round into the chamber and force the bolt closed? If so, wouldn't it be a bigger problem if the shell casing got stuck in the chamber? (I never had a gun with a forward assist.)

Yes. If you examine the bolt carrier of an M4/M16 type rifle, there are these little notches in it. The forward assist interfaces with those notches to, yes, ram the bolt and carrier forward into battery. This is only useful for this failure to return to battery type jam, and only as long as the gun isn't too fouled by carbon buildup or external debris.

Certain guns have no need for this as they have inherent forward assists, like the AK's charging handle being directly on the bolt, or the slide on a handgun, the piece that interacts with fed rounds. Additionally, you'll hear people refer to the slide as the "bolt" because they probably also handle M4/AR type rifles and it's just the vernacular, but there isn't really a "bolt" with handguns (except maybe the Desert Eagle), just a slide, which more or less serves the same functional purpose. The More You Know.

Doing a forward assist could potentially jam a malformed round into a chamber, or a normal round if the chamber was really dirty. However, the force of the gas system on the bolt is stronger than that of the bolt spring (otherwise the gun would never cycle) meaning that if there is too much friction in the chamber to prevent the spring from locking the bolt hence requiring a forwards assist, the gas pressure would normally be more than enough to overcome this friction to extract the round. Also, I think that there would probably still be a slightly higher pressure in the chamber giving the case a slight blowback effect.

Which is always wise to actually see what kind of jam you have on your gun before you do anything to it like smacking it needlessly

When you can it is definitely a good idea to work out why a stoppage happened, but if you are in a firefight you will just follow your immediate action drills. Tap the magazine, open the bolt, look in the chamber, if clear release the bolt, forward assist, shoot. You will probably have no idea what type of jam it was other than it is now fixed. Depending on how much of a rush you are in you might not even look in the chamber as that is only useful if you have a double feed, which is relatively rare in comparison to other stoppages.

No that is the old way of doing it. Marines don't even use the forward assist during a jam today. It's either tap, rack, bang if you are in a pinch or look at the chamber to see if its a double feed or stovepipe, solve it and get back into the fight as fast as you can. With SPORTS, you don't know what is wrong with your rifle but you are already trying to solve an unknown problem. And SPORTS isn't immediate action. It's remedial action.