The OTHER variability is in the design of your trigger and also your method. The good news is that 4 clear plastic tubes are included with the case. Just shot 5 rounds at 50yrds, but could tell immediate results. Gets worse in the 7 LB range as it is closer to 7 LB- 6 OZ. Draves has some other cool videos to check out too while you're on there. Way to think outside the box Bowmar! After install I've shot about 300 arrows and still in great shape.