Just wondering if anybody else has had the same problem I'm having. The ST Epic .300s I'm shooting now just don't want to group,tune ,or fly the same. I've done the usual stuff like change nocks,checked for cracks,etc.Most won't even shoot thru paper the same and my form and shot execution are good. APA Mamba M7 70 lbs,28.5"draw AAE D.O.A rest 28" Easton ST Epic .300 (yes I know this is on the stiff side) 100 gr Rage-296 FPS
I've had my target coach say carbon express shoot great out of the boxe but then go away after being shot 3-4 times. Not sure if its true but he should know and be sells them.
Although way to stiff can still tune sometimes I would say that is your problem. Your arrows are extremely stiff for your setup.
Carbon fiber arrow are either good, or they are broken. Nocks will wear out and it's good to make sure each has the same amount of drag.
CX Arrows I have cx arrows that are 5 years old that have passed through my fence CX 300's old spine numbering system that still group as tight as my newer Blue Streak 350's.
I would not worry too much about your spine. It may be a bit on the stiff side but these are guides. As such, a bows performance level comes into play as well as the other listed factors such as shaft and draw length, draw weight, tip, etc. A cheap test is to try heavier tip weights or heavier inserts. If a 125 or 145 grain tip give better flight then you need to adjust spine but either using that heavier tip, going to a longer shaft in the same set up, or lighter spine shafts. The greater f.o.c. achieved with the heavier tip/insert may help your shooting as well
How much do you shoot? Not trying to be a smart a$$ but, I've had problems spring up like this, in the past. Arrows don't group, don't fly right, hit high, hit low, etc., etc. I blamed the arrows, the bow,.... everything but the problem. Arrows (provided they are straight and components in good shape) don't, generally, go bad all at once. It's usually either a small movement/shift in bow setup (rest moved or worn, nock moved, string/cable stretch, etc.) or more commonly, in my case at least, a minor form change (grip shift, bow arm position, over/under draw, etc.). Before you spend a lot of time and/or money, check your bow and be sure nothing has moved or broken then do a little review of your form. This might not be your problem but, it doesn't cost anything and, it's good to do on a regular basis anyway.
