Happy New Year to you.Happy new year, I am sure it's possible too shoot 20 inch arrows out of an excalibur bulldog 330 that shoots 18 inch arrow, any difference?
For every 10 grains over what the manufacture supposedly used to obtain their advertised speed, a well tuned crossbow will lose approximately 3 feet per second.
Adding length to the shaft only will increase the weight per inch. Some bare carbon arrow shafts weigh more than others. Different vanes, even the same length can result in weight difference. Nocks and insert weights can vary.
All the best.