I was curious, so using your posted specs and low end of Onza3 listed IBO rating of 330-340, I ran it thru a OnTarget2 program.
Originally Posted by vegas steve
Not sure which Linejammer arrow you use or length (must be pretty short) but finally got one down to 322grs..............Program calc'd 306.41 fps
Assuming bow is tuned/timed right as mentioned:
Did you verify against another chronograph?
Was chronograph in good outdoor light?
Double check draw weight w/another scale? (one of our bow shops in town swears it's scale is right on, but shows my bow 6-7lbs heavier than mine (that I know is correct) and 2-3 others I've tried)
I have had slightly lower fps right at first with new string until shot in a bit, but not more than 2-4fps lower
2009 Martin Bengal M2 Pro Cam w/factory STS & CCS.....66lbs, 29" DL, 422gr @ 272fps, Winners Choice string/cable, Trophy Taker drop-away Rest, Scott Release
1996 Martin Firecat XRG Pro Series w/Ultra Sonic wheels.....69lbs, 29" DL, 465gr @ 245fps, w/fingers & Martin leather glove