Overspinning is only an issue when the bullet falls apart. Yes, it CAN reduce the BC of midweight bullets but this is only at very long distances as the bullet axis does not track trajectory.
Now with the lighter bullets in .223 Rem having pressure issues with a 5.56 NATO chamber, this could be due to many factors which cause secondary ignition. One is a worn bore, the other is the chrome plating offering less starting friction. It is REAL and can be a serious problem with a badly worn throat. RSI and their most excellent Pressure Trace hardware/software has shown this, usually with lighter bullets and spherical propellents. Scary pressures...
Note the initial maximum pressure is well under the SAAMI maximum, this is a sign of something slowing down combustion. It took a bit of what I call "heat soak" to cause the bulk of the powder to become sensitized to the point of ignition, this is the undesired function of deterrent coatings on the individual granules, a form of either intumescence or ablative effects. Either way, the granules which have not ignited are now much more sensitive.
This can also happen to ball ammo, the following is presumably Q3131/a.
Again, note the initial maximum is well below SAAMI or the specified maximum for M193. The barrel is a CM 1:8" with about 3500 rounds down it, this caused the initial bullet friction and ignition pressures to be high but also abrasion of the bullet, making its fit in the latter bore to be imprecise. This resulted in the bullet having less control over the pressure rise and a premature quench of the cumbustion until the heat soak effect cause remaining propellent to burn much faster than specification. Or application. If proof loads are in the 75k range, this load would definitely shuck primers.
For the record, OBT markers are optimum bullet timing marks. Having the bullet exit at these points is conducive to accuracy.