The bias that some shooters have against Turkish shotguns is generally unfounded. Turkish guns are no different than those made in any other country - they make some spectacularly fine guns and they make loads of crap. Every gun, regardless of where it was made, has to be evaluated on it's own merit. Having said that, the Turks are the country that currently make the highest volume of inexpensive guns. In order to make guns inexpensively, you have to reduce labour costs, cut back on material quality, and and eschew fit and finishing effort. The old axiom "you get what you pay for" is especially true with shotguns.
Being prudent is good. Being paranoid is not. So, always inspect your firearm before use. Signs of loose joints, rust or corrosion, or damage should cause one to reconsider the use of such a firearm if not choosing a different gun altogether. A good example would be a dent in the barrel(s). Dented barrels are a risk factor even with bird shot. All the more so with slugs.
My biggest concern with cheap shotguns (be they Turkish, Brazilian, Chinese, or an old Belgian clunker) is that they can be damaged or get loose in a fraction of the time it would take for a quality gun. That being said, if your Turkish shotgun is in good condition and functioning properly, there's no reason why you can't fire slugs through a modified choke with it. However, many of the so-called "tactical" shotguns are far too light for heavy shot shells and slugs. The recoil can be punishing to both shoulder and trigger hand.
Foster Slugs and Brenneke Slugs (often referred to as "rifled" slugs) have angled grooves cut into the lead. These grooves will compress as the slug passes through a choke that is narrower than the full diameter of the slug. This helps keep the slug in contact with the barrel as it passes down the bore and equally as it passes through the choke. If there's anything left of these vanes after leaving the barrel, they are said to impart a spin on the slug that provides stability for better accuracy. The tighter the choke, the more these vanes are crushed going through. So much for stability and accuracy!
This is why some slugs are more accurate through IC and some are more accurate through MOD - the best accuracy comes from the constriction that best fits the diameter of the slug without excessively crushing the vanes.
Sabot slugs are solid lead slugs with no vanes. They are intended for shotguns with rifled barrels with little or no choke. Some newer versions retain a plastic sleeve as they travel down the barrel. This sleeve easily compresses going through the choke, providing the same seal to the barrel and choke walls as do the vanes with the previously described slugs. The plastic sleeve is intended to drop off after leaving the barrel. Theoretically these sabot slug are safe to use in smooth bore shotguns, but I wouldn't take that chance - especially though a choked barrel. Sabot slugs don't all have this feature and there are plenty of easily available suitable alternatives to not be taking such risks, especially when using cheap shotguns.