As a chinese
I had a couple chance to shoot 81- and Chinese SKS
The my result:
81- about 6 MOA
SKS about 7.5 MOA
I am bad at iron sight, I can shot my SKS with 4x scope about 2-4 MOA, so I would like to say 81- is at least more accurate than SKS.
I just did a little research. Based on the inspection report of both rifle in Chinese military.
81-was able to shoot R50=3.9cm, SKS was able to shoot R50=4.7cm, Chinese AK47 Type 56 shoots R50=over 6cm. (Iron sight)
R50 is a different way to measure accuracy, R50 : MOA =1:6