Tuning Huma reg and hammer spring tension

[Barzor]

I’m sure this has been asked in the past. I have a smk pp700sa with 16 inch barre. I have the reg at 155 and the HST screw turned 5 revolutions.
I can only get 10 good shots then dies off.
I notice that everybody is getting around 20 shots. Should I decrease the HST first to get more shots?

I don’t understand the numbers in the reg.
Does the 155 mean that the gun will hold at 155 on the pressure gauge?

I can’t understand the numbers on my huma reg.

 

[Barzor]

SO I tried doing some tuning and weird thing happened

First I tired increasing hammer spring when the tank pressure was only 1/3 full going to empty the velocity started going up rather than going down.

Second time is reduced the reg to 140 and also lowered the HST. once again strange results the velocity would remains steady to about half tank then suddenly it would dip down to almost 100fps then go up again.

I finally decided to go back to the original setting of 151 on the reg and the HST same as original setting with a touch increase. Its giving me great velocity, fpe and sd. Im just going to stay with 10 shots.

SInce the touch or the HST increase and the reg at 151 it seems better I will try to o a string of 20 and see if velocity remains stable.

All this started because I put at 16 inch barrel thinking that it would give me enormous velocity gains. There was gains but not as much as I thought

Does anybody have or know the average velocity of pp7oosa with 16 inch barrel and huma reg at 150 and the HST screw is almost flush just enough room for a wrench head to turn the screw? I forgot with 22 in the 25,40 grains?