@lash I have not done someone elses homework since 1984 and I can assure you she was alot hotter .. that said
first.. the paper is not my research, but was required reading, it s peer reviewed and I believe the data to be sound .. and again, pilots feel this ground effect on every takeoff and landing.. its a fact..
now to the differences from the research paper to magneto application..
first and foremost.. there are many more vairables at play than the paper takes into account
the surface is fixed and not moving.. they did do studies with angles and when the bullet was fired into rising surface the projeclite nose up rotation was assentuated.
it also doesnt take into account barrel whip and barrel harmonics, and the forces of the expanding gasses that accompany the bullet from the muzzle..
my hypothisis is this.. and its untested and unresearched
1 .. loads where the bullet is launching in the optimal barrel time where the muzzle angle is rising would be bringing the bayonet closer to the bullet at it was flying over it.. increasing the effect of POI climb.. loads where the muzzle angle where whiping low, would conversly pull the bayonet surface away from the bullet as it passes over, showing little to no POI shif on the projectile as the 'ground plate' is sloping away.
2. dump gas volume and pressure is differrnt for every load., barrel lenght etc.. also effected by brakes and cans that redirect or slow and cool the muzzle blast.. possibly explaining why most that shoot the system with those devices tend to see less of an effect and that is the case in my own AR as it has a 3 port lateral brake.
3. external ballistics are still in many cases magic as they are hard and expensive to study and effected by so many variables
I can say that with regard to magnetospeed many see the same movement of group as the bayonet is rotated... with the group alwasy moving away from the surface of the bayonet.
also, many have reported that even after buying off-barrel adapters of various designs, mostly for AR platforms, they still see a shift.. so it cant just be barrel harmonics and suface aerodynamic friction is a proven force acting on said bodies and fits the theory..
here you can see clearly that at a height of .75 of projectile diameter the shockwave reflections are interfering with the body, and the tail is loosing lift pointing the bullet up, at 1.77x diameter the reflection passes behind the projectile
expanded view of hight to diameter distance and effect of lift/drag at the boattail