It is impossible to tell from a picture if a barrel has been turned down.
If you plan on threading a 2003 model SAR1, WASR or a MAK90, you need to measure the outside diameter of the barrel at the muzzle. If you don't have a set of calipers, just hold a ruler across the end of the barrel. If you have a metric ruler, it needs to be close to 14mm. If you are using an inch ruler, it needs to measure about .551" (roughly 9/16 of an inch.
Some of these guns have had the barrels turned down, leaving them too thin to thread with a 14mm die (standard for AKs). The good news is that most of them can still be threaded with my ½ x 28 threading kit.