JSB .25 Heavy MKI vs MKII: Much difference?

[Mr.H]

I've been getting very good groups shooting JSB .25 Heavy MKII in my Standard Taipan Veteran. Harmonically , I have the gun shooting those at 840 fps. I'm curious how different maybe the MKI is in comparison, as I've never played around with those. Thanks for any feedback!

 

[JCD]

I've been shooting the heavies for a couple years, in a couple guns. My previous .25's didn't like the MKI's. My current .25 shoots both equally well with MAYBE a slight edge toward the MKI's. But I'm shooting them a little faster, 890ish. That might make a difference. I would suggest you test them in your gun at your speed. 

 

[Jayson]

my Vet does shoot the mk1's a little better also, prefers the aa25's over the jsb kings. 

 

[JoeKool]

If my memory serves me correctly, when the 33.95 MKII’s were released, the redesign was mainly to accommodate for the pellets to fit in more various PCP brands magazines. I believe some brands magazines had trouble with the head size or length of the 33.95 MKI’s This was documented somewhere on a popular YouTube airgun content creator’s review. But, I at this point have no recollection of who stated that. Maybe it was at a old Vegas ShotShow when one of the YouTube guys interviewed a representative from JSB. They perform exactly the same from my airguns, I use both..

 

[bdzjlz]

From my RAW shooting them at about 890, there is minimal difference at 100 yards, with maybe a slight edge to the originals.

 

[sonny]

I have shot both equally well through my Impact. The mk2s are a tiny bit shorter...(910fps)

 

[Macloaded]

I shoot both out of my Impact (700mm with superior pellet liner) at 850ftps and can't really tell the difference at 50 yards. In my old smooth twist the Mark 2s shot better but I think that was related to the streamline magazines. 

 

[lopey15]

I've never tried either of them in my Airforce Condor 24" barrel...has anyone had better luck with one over the other in their Airforce?

 

[Stikman]

The original .25cal 34.95gr King Heavy’s are deadly accurate in two AF guns @ 950fps, a Condor and a Talon that we hunt with.