Same thing on my Ripper 415 first time, fortunately I had stepped out of the stand at the time. Opening weekend of the season... Less than 40 shots, new out of the box, not a scratch on it. Was not dry fired, was not misused, was not abused, was not dropped, dinged, or otherwise damaged. In fact, the only scratch on it when I parked it after 3 years use, was a result of changing limbs. No parts available the first round, order got misplaced, brand-new crossbow, and I missed the entire season, waiting on parts.
Reordered June of the following year, had my parts in 2 days. Replacement set was 425 limbs, got maybe 30 shots out of that set, and the left side split a limb straight down the middle from end to end, mid-stroke while cocking it. Third day of the second season. Took 28 days to get parts that round.
Meanwhile, the neighbor's KI had broken a limb sighting it in that season, he replaced limbs on his, sighted it in, first day on stand with it, cocked it, set in his rest, and 5 minutes in, heard a snap, and sat there and watched a new limb with less than 30 shots on his fold up. His was dumpster bound after he got off the phone with Customer Service, talked him out of it, robbed the surviving limb off it and made mine whole again. Backed a twist or two out of string and cables in the process, which I was later told does seem to help, and thus should have helped.
Made the remainder of that season, and all the next season without a hiccup, was actually beginning to think I had solved the problem, and was really beginning to like the thing.
Season 4 opening weekend, afternoon of the second day, hooked up the pull rope to cock it, and halfway through the pull, the left side just turned to jelly, no resistance there at all. Once again, delaminated limb in the process of pulling it back. Packed it in, came to the house, got on Amazon and ordered a Barnett XP380. Had replacement limbs in the shop for the KI, refuse to put the time and effort into rebuilding the POS. Failed 3 out of 4 years opening weekend, twice with less than 40 shots on the limbs.
Does shooting 450 grains help? --- NOPE!
I was shooting a 450 -455 grain combination on the last three sets that failed. Only time I ever shot the factory bolts, was when I sighted the bow in the first time. Bow was kept in a case, inside the house, never dropped or abused in any manner, strings and rails were waxed and lubed faithfully, never dry fired, bow sets on rest at eye level in the stand, always double checked when sighting it in, bolts were always properly seated. I've heard about every reason imaginable why it was my fault, and none of it held water.
Warranty was great, Customer Service was great in the off season; Customer Service was pretty much non-existent during season. Sat on hold 45 minutes, sat on hold 38 minutes, e-mails were ignored repeatedly. web forms submitted got the quickest response, but then they went to e-mails with questions in reply, and they got lost in the shuffle. Was promised on more than one occasion parts would go out ASAP, parts didn't go out ASAP. Required more web forms, more e-mails, more phone calls to get what I needed, every time I dealt with them during season.
NEVER AGAIN WILL I OWN A KILLER INSTINCT CROSSBOW!