We had this happen in our game too, but during the final fight against a hive tyrant, so it was cinematic enough for the devvie to his H-bolter on it's strap and start blasting away with his pistol.
I think i would house-rule it so that upon getting a jam and clearing it (the full action as in RAW), allow the player to make a Tech-Use test. A success reduces to amount of a clip lost to 75%, with each further degree of success reducing it by another 25%, to a minimum of 1 shot lost (so passing the Tech-Use test by 40+ would mean you only lose 1 shot). You could rule that the test is extended depending on the weapon in question, so Full Action for pistol, 2 Full for Basic and 3 Full for heavy weapons.
I feel this solution should clear up the vague and non-sensical system as presented in the book.
Only the insane have strength enough to prosper.
Only those that prosper may truly judge what is sane.