Hi, Last week finally i recieved my JP5 here in the Netherlands ( Europe ) Did some testing with it and have a question hopefully someone can help me out.
I use it for IPSC so a minimum powerfactor of 125 is required.
I tested with VVN320 powder and 124 and 115 FMJ RN bullets.
The 124 with a 4.0 gr load did 128 PF
The 115 with a 4.3 gr load did 130 PF
Using the 70 locking piece Dot movement with the 124 and 115 is about the same, but the 115 with the 4.3 load feels a bit snappier and faster. So for now i am gonna settle with that.
So far i am very happy with the gun, till 15 yards superfast splits are possible with te bulletsholes almost touching. So that is a big pro compared to my GMR15. But at 30+ yards the dot movement is still a litte more than my liking. Hopefully i can finetune that.
I could be totaly wrong. But in my thoughts, When the gun fires the bolt pushes the rollers to a locked postition, till the spring tension on the other side takes over and unlocks them. So with a lighter spring the longer the bolt stays longer locked and there is less energy left to cycle the gun.
I have read that Max uses the 70 locking piece and the heaviest SCS spring with a 115 gr bullet and a lighter spring with heavier bullets, What i still dont understand, what"s the idea behind that. Can someone please explain this to me.
Regards Reinier