N340 Berry's Hybrid Hollow Point load data

[mercervillerental]

So...I'm at a little bit of a loss. Would love advice, wisdom, or just to be told I'm overthinking this and keep working up.

I have some Berry's 124 HHPs and loading N340 according to the data on VVs site. Usually I find results are at least in the ballpark of what a manufacturers load data specifies. Yeah...not so much this time.

With the starting load of 4.2gr of N340 under a 124gr Berry's Hybrid Hollow Point in a Starline case I saw an average 3 shot velocity of 818fps out of my VP9 when VV suggests it should be 974 out of their 4 inch barrel. Thats a 156fps difference, which I wasn't expecting at all. My rounds were loaded at 1.130, just barely longer than their recommended 1.126.

With VV's 147gr loads and Xtreme bullets I saw differences that seemed much more reasonable, in the 30-40fps range. Same brass, same primer, same gun, etc

Any ideas why I'd see such a drastic departure on the 124gr HHP's?

 

[Walkalong]

N340 under a 124 in 9MM is good stuff, but that’s real light.

What length test barrel?

 

[mercervillerental]

According to VV it was 4 inches, same as my VP9. I'd love to think I totally screwed something up or missed a measurement somehow but I just can't see it if I did

 

[fxvr5]

Different gun, different results. Different cases, different results.

 

[reddog81]

Your FPS seems slow. I've got some data with that powder and similar bullets.
Walther PPQ Q5, 5" barrel, 124 grain lead SWC, 4.3 grains N340 - 1089 FPS
Glock 17 with threaded barrel, 125 grain lead Lee WFN, 3.6 N340 - 845 FPS.

Maybe your bullets are too small in diameter and some of the gas / pressure is blowing by.