I don't like bowyers knots on heavy warbows too much anymore, not because it slips, but because it has a tendency to damage the nocks at heavier weights. (Well this is mostly really for bamboo backed bows, but I have been making a lot of them lately). Like clockwork, it always starts to split the bamboo. It's aggravating sometimes because it forces me to put the horn nocks on before I can really be certain of the weight, potentially causing me to come under weight. I'm surprised I haven't read of anyone else having this problem, I don't make my temp nocks any different than anyone else. I have switched to using two loops on bows 100+, which really ain't too big of a deal if you make the loops like I do. The way I make em, I can just unravel the string and lay the tails of the loop in and then twist the string back up, however many times I need to, to adjust brace with a two loop string.