My friend came over with his bone-stock, DPMS Oracle. The Oracle is DPMS's entry level AR. It has a whopping forty rounds on the clock.
The rifle was at room temperature at the start of the test. It took all of five minutes to run so temperature was probably not a variable.
The 55 grain loads with 22 grains of H-4895 all cycled fine.
Two-of-five rounds with 20 grains of H-4895 failed to feed. The bolt stripped them out of the magazine but they did not enter the chamber.
Any statistician will tell you that we need to fire a bunch more rounds to map its performance. This experiment told us where to look.
Practical people will accept that even a little bit of data is better than wild-ass guessing. So, until more testing is done any mods must be 100% reliable at 22 grains of H-4895 with a 55 grain bullet if he wants to retain the "factory" performance.
The Hodgdon reloading site lists 26.0 grains as the top end for one brand of 55 grain soft-point bullets. That suggests a range of 22gr-to-26gr of H-4895 or from 86%-to-100% where 26gr is 100%.