The "M59" Yugo SKS has No grenade launcher. It never had one. Therefore, normal c.g. (center-of-gravity)/length for an SKS. A 59 Is Not a 59/66.
If anybody suffers bad 'popped primers' in an SKS, the Permanent cure is done by Murray's, in Bowie TX (near Ft. Worth). Moderate cost, even with shipping. Both of my 59s went to his gunsmithing shop and were shipped to my front door,
near Memphis TN.
Mr. Murray has his own forum at "SKSboards". My advice: avoid Tula ammo in some SKS as much as possible. Wolf might not cause these problems. Tula blew a firing pin Out The Rear of my SKS bolt!
As for the Hungarian AMD-65 'AK' derivatives, a small gun shop in Nesbit MS (very close to Memphis) might still have a few more 'TGI' AMDs. They bought several last fall in an estate sale.
Both of my TGIs have matching receiver/bolt carrier/dust cover.