The lower serial on the top cover looks Yugo. Probably was one of the Yugo top covers missing the crest (not all had it) and someone added the fake markings.
I think that blank ammo is PRVI PARTIZAN, made in Serbia. We use it a lot in the UK, as we can't shoot live, and it gets imported in enough quantity to satisfy the reenactment and movie markets.
Oh, and screwing restrictors with differing hole diameters (2.0 to 5mm is a common range) into the end of a normal barrel is a way of getting the guns to cycle properly, here in the UK. The different diameters enable not just the varying power of the different ammo (7.62 Nato blanks are comparatively weak) but also weather conditions to be taken into account.
My local Section 5 Armourer has an ingenious method of threading the booster cup and fitting a countersunk slotted bolt in from the inside (so it can't slacken and blow out) that has the varying hole sizes drilled down the middle. Changing the restrictor is as easy as removing the booster cup and unscrewing/screwing a new predrilled bolt till you find one that works best that day. Also means he can use either 7.92 or 7.62 barrels and either size ammo depending on what is required. The best 'bangs' undoubtedly come from the Prvi Partizan stuff, as I said the other extreme is the Nato 7.62, quite puny by comparison...