I have had one. With the emphasis on "had".
After a stockfailure... ( see added pic)
... and a 3 month wait for its replacement I put about 1200 rounds through it over a 2 month period.
In that period I experienced an increasingly number of FTE's, with various brands and velocitys of ammo.
Ammo used: CCI standard, blazer, minimag, american eagle HV, winchester wildcat.
In this picture you will notice 2 bolts on the left side in the frame - one vertical, one horizontal. These bolts and the parts they hold together are vital for proper functioning of this gun. They keep tension on the boltassembly. Ones this loosens one will experience FTE's.
Unfortunately - ISSC made a very poor choice in material for this gun. The metal parts and the aluminiumalloy frame are so weak, that during these 1200 rounds I managed to destroy the threading on the vertical bolt. The pin construction got wider tolerances and with every shot that pin gave the frame a beating resulting in oval holes instead of round holes. Thus even widening the already large tolerances in that area. In the end tension could no longer be held on the bolt assembly in such a matter that the vertical bolt comes loose in 3 mag's time and rattles inside the inerts of the gun while I was trying to use this gun as a bolt action rifle...
I brought it back to my gunsmith and he decided that this one and the one he had in stock were going back - never to return again.
Bottom-line: the concept of this gun is great, the design due to its difficulty of cleaning less desirable. But because of the poor choice of materials used... It's crap (pardon the expression).
And I can honestly say: Been there, done that and I've got the frikin' T-shirt.