"G" engraving

Chowchescoo (or however you spell his name) was a mean SOB. There was a plot/attempted coup against him in 83 and in response he had all the old line generals and supervisors who had any chance of raising or arming the opposition against him jailed or killed. That included the old world craftsmen that ran the AK arsenals. Didn't want them passing out any party favors to the peons, as it were. They were replaced by, let's say "less motivated" individuals who didn't put quality above quantity as much as the previous foremen. Also, around 80-81 the arsenals started going to cast and simplified/rougher parts as a cost cutting measure, so parts made after that date exhibit a rougher finish.

DStorm1911 over on the AKfiles has an uncle who was jailed over there for 5 years because of the purge, he was one of the old line guys at the arsenals. Lots of interesting first hand info from him is posted over there.

The AK Files Forums - When did Romy G's quality go down hill?

You might want to read that thread again. His first post is specific, according to him 1983 is when things went down hill.
His third post says 1980 was the last year for hammer forged barrels and forged gas blocks and front sight bases.
He goes on to post that the cast gas blocks and front sight bases were well finished until '83.
He posted that '83 was when everything went to "hell" in the country.
Unfortunately, direct observation by myself and others doesn't confirm what he posted, which isn't a surprise.
The difference occurred sometime in 1980. There's no way to tell exactly when it happened, but it occurred at the same time the Romanians stopped putting the arrow in the triangle arsenal mark on "G" rifles and added the letter "S" in the serial number after the date of manufacture on those rifles.