I’ve owned both guns you ask about. Both really nice but I sold the Tiapan because I liked the ergonomics of the Vulcan so much more than the Tiapan. I have the synthetic stock.
I shoot JSB 18.13 gr. at 870fps and I can get 70-75 shots filling to 225 bar. Quarter sized 10 shot groups at 75 yards. I’ve shot dime sized 5 shot groups at 75 yards-see my avatar. I’ve had the gun 5-6 months and it’s been reliable.
I did add a DonnyFL Tatsu to make it quieter.
Here is a shot string:
"Created","Description","Notes1","Notes2","Distance","Coeff","Weight","Temp","BP","Altitude"
"08/22/18 04:13 PM","Vulcan JSB 18.13gr 72 shots","75 yards 5-7mph switching winds","220 bar fill","1.00","1.000","18.13","78 °F","29.22 inHg","0.00"
"#","FPS","FT-LBS","PF"
"75","851","29.16","15.43"
"74","855","29.43","15.50"
"73","862","29.92","15.63"
"72","868","30.34","15.74"
"71","868","30.34","15.74"
"70","864","30.06","15.66"
"69","871","30.55","15.79"
"68","869","30.41","15.75"
"67","868","30.34","15.74"
"66","871","30.55","15.79"
"65","874","30.76","15.85"
"64","869","30.41","15.75"
"63","870","30.48","15.77"
"62","866","30.20","15.70"
"61","866","30.20","15.70"
"60","865","30.13","15.68"
"59","871","30.55","15.79"
"58","868","30.34","15.74"
"57","862","29.92","15.63"
"56","863","29.99","15.65"
"55","864","30.06","15.66"
"54","869","30.41","15.75"
"53","866","30.20","15.70"
"52","876","30.90","15.88"
"51","872","30.62","15.81"
"50","872","30.62","15.81"
"49","869","30.41","15.75"
"48","861","29.85","15.61"
"47","869","30.41","15.75"
"46","871","30.55","15.79"
"45","867","30.27","15.72"
"44","867","30.27","15.72"
"43","875","30.83","15.86"
"42","871","30.55","15.79"
"41","870","30.48","15.77"
"40","865","30.13","15.68"
"39","871","30.55","15.79"
"38","863","29.99","15.65"
"37","869","30.41","15.75"
"36","865","30.13","15.68"
"35","872","30.62","15.81"
"34","861","29.85","15.61"
"33","870","30.48","15.77"
"32","866","30.20","15.70"
"31","872","30.62","15.81"
"30","871","30.55","15.79"
"29","871","30.55","15.79"
"28","861","29.85","15.61"
"27","868","30.34","15.74"
"26","865","30.13","15.68"
"25","872","30.62","15.81"
"24","868","30.34","15.74"
"23","866","30.20","15.70"
"22","870","30.48","15.77"
"21","865","30.13","15.68"
"20","873","30.69","15.83"
"19","868","30.34","15.74"
"18","869","30.41","15.75"
"17","865","30.13","15.68"
"16","867","30.27","15.72"
"15","874","30.76","15.85"
"14","871","30.55","15.79"
"13","871","30.55","15.79"
"12","871","30.55","15.79"
"11","870","30.48","15.77"
"10","873","30.69","15.83"
"9","871","30.55","15.79"
"8","871","30.55","15.79"
"7","874","30.76","15.85"
"6","871","30.55","15.79"
"5","871","30.55","15.79"
"4","870","30.48","15.77"
"3","872","30.62","15.81"
"2","875","30.83","15.86"
"1","876","30.90","15.88"
"Avg","StdDev","Min","Max","Spread","Shot/Sec","True MV","Group Size"
"868.5","4.5","851","876","25","0.0","869","0.00"