With small scales of bullet simulations, you need to use minimal pieces of the order of centimeters. You can not use millimeters. Scaling in 20 times from 2-4 mm to 4-8 cm solved many problems.
In this case, it is necessary to increase the time scale by sqrt(n) times, where n is the increase in scale. For n = 20: time scale = 5. The comparison with the test simulation of the real scale coincided in behavior.
Substeps also need to be increased: substeps = time scale = 5. In the case of bullet sim, you can increase the number of substeps on the solver by a multiple of this value:
old = 10, new = old * time scale = 50 or more.
Example: time scale = 4, number of substeps = 10, new value = 60. This gives the same result as increasing substeps of the DOP network, but several percent faster.
An increase in constraint iterations will not produce a change in the result, since the need to increase the substeps is caused by the high speed of the objects.