Subsonic Whispers shoots higher than Supersonic, how come?

[alwaystryin]

I sighted in a 300 whisper with factory CorBon 150 grain sp. This load is advertised at 2000 fps. It grouped into one raged hole, about .35 inches center to center for 3 shots. This is a T/C custom shop 10 ¾ inch barrel I just got and Scoped with a Bushnell 2-6.

I then switched to 175 grain MatchKings with 10.7 grains of H-110. I think this load should be about 1100 fps.( but I don’t have a chrono). Not changing the scope settings this load printed 2 ½ inches higher and about ½ inch to the left. It only shot ½ inch groups.

Using ballistics software it shows the slower 175s should have shot lower than the faster 150s. Can anyone tell me why my real world testing is opposite of the math.

The ballistics software also shows the 2000 fps load recoils at 11lbs.
While the 1100 fps load recoils at 4 lbs.
Should'nt this lack of recoil on the part of the slower load, cancel the fact that slower bullets shoot higher due to more barrel time?

Thanks

[BCB]

Common with revolvers/handguns.  The heavier bullet is going slower thus spending a bit more time in the barrel.  This gives the barrel a bit more time to have recoiled upwards before the bullet exits.  Thus the higher point of impact...BCB

[IntrepidWizard]

Think about it.

[Robert]

I experienced the same thing with my 7TCU.  I was shooting out to about 250 yds with fast 100 gr Sierras and needed to hold my scope up to the bottom duplex of the reticle.  Then I tried 168 gr cast with light loads, and couldn't see where they were hitting, they were going clear over the top of the target area.  Turned out, I could put the crosshairs dead nuts on the target and they were accurate too.  Dosent seem to matter if it is a boat-tail, just heavy/slow bullets.

[Steve P]

You have a different arc in your bullet travel AND you have a different type of recoil.  Some say the lighter bullet, coming out faster, will recoil straight back toward you (part of the time in the barrel theory) and the heavier and slower bullet, will give you more of a rocking recoil, barrel lifting up.  Whether it be the arc of flight or type of recoil, doesn't much matter.  What matters is now you know, at a given specific distance, your heavier/slower load will print higher than your lighter/faster load.  As long as you know this difference, you can adjust your point of aim, and hit what you are shooting at.

Hit that target!!

Steve