You are never going to know if your arrows go into the taret straight because they will move when they hit it. It might work on a 3-d target, but not a bag target. If you have fletchings on the arrows they are straight by the time they hit the target. That is what they do.
I know he's made up his mind , and I dont blame him , but I just wanted to respond to what Paul said.
Checking the straightness of arrow impact has been a part of the tuning process for years (longer than I can remember) , and it certainly will help with any indications of bad arrow flight.
However , Paul is correct , that the loose (bag type) targets shouldn't be used in this process.
If you shoot a group of six arrows (tight group) into a solid target straight ahead of you , and all six arrows are angling in the target with the fletching end to the right or left , you have flight issues (fishtailing). Or the fletchings are pointed up or down (porpoising).Yes , your groups can be great , even with these new broadheads that fly like fieldtips , but your penetration will suffer.