Frankie,
No offence, but I call utter bull-shite. If any member of the CF within my sphere of influence ever allowed a C1 SMG to become so filthy that it suffered a catastrophic failure of the trigger mechanism, then that soldier would have been in a serious world of hurt. It would take quite literally unfathomable volumes of fire under field conditions to render the trigger mech on a C1 SMG unreliable due to fouling (vice parts wear). The only time I personally came close (in 6 years of using an issued SMG) was in Yakima in the early 1980's after Mount St Helens had blown and the training area was covered in abrasive volcanic ask. A helicopter rotor-wash would blow all kinds of unwelcome grit into a weapon's working parts. Even under those conditions, the trigger mech of my C1 SMG never failed. True, the bolt would not slam forward when the trigger was pressed (it ground to a halt half-way forward), but the trigger mech was fine. After all, there was only 1/4" of access around the receiver's sear cut for fouling to enter the trigger mechanism.
Some folks here seem to be confusing personal C1 SMG experience with unsubstantiated wives-tales concerning the "c@ck and throw" Sten SMG. Even the notion that you could c@ck the latter and throw it into a room expecting a trigger mechanism failure and a 30-round "party favour" are patently ludicrous. I own a Canadian Long Branch Sten Mk 2, and it's trigger mechanism is utterly reliable. The sear is rock-solid.
This business of slamming the butt-stock of a C1 SMG on the ground and having the bolt travel back under inertia just enough to pick up a round from the mag and fire it? Absolutely true. BUT - only if you were such a poorly trained idiot that you did not engage the "Safe" setting on the trigger mech, which would infallibly lock the bolt in either the forward (closed) or rear (open) positions. In other words, the ONLY way that the C1 SMG could unintentionally fire from a closed bolt (eg. loaded/made ready) is if the operator was sufficiently dense or untrained that the selector switch were not properly placed on "Safe" IAW the extant handling drills.
In summary, there was NOTHING unsafe about the C1 SMG other than ill-trained operators. Full-stop. I happen to personally own one, and had the pleasure of carrying one on repeated occasions during my 6 years in the Reserves. It was a fine 2nd Generation SMG. The only "accidents" that I ever saw were a sole function of user inadequacy.
For what it's worth....