My buddy I fish with a big time hard hook setter.  I wish I had a dime for every time I saw him snap braid on hookset.  All brands, all weights.  But hey, "I can pull in ten foot logs" he uses in his defense.  Personally I would rather hook 3 pound bass than land ten foot logs.

 

When I got into fishing again and started using braid I thought it was the best thing since sliced bread. I could feel everything so good it seemed and I never had to retie cause it was indestructible. I could do whatever I wanted it seemed with no fear of breaking off. Little did I know that underneath my line was getting weaker and weaker from getting silly with hooksets and never retying anything unless it involved a lure change. After breaking off so many times fishing plastics I realized it had to be from me trying to catapult the out of the water with a slack line hookset.

could be your casting technique...if your overhead whip casting (like cracking a bullwhip) vs letting the rod load it can/will snap off...15# is light & no stretch, bad casting technique will do that to you if all else is in order with your knots, no guide flaws or damaged line etc...

 

that is if its snapping up the line in places vs definitively at the knot itself...

Yes I agree if the break can be detemined to be downline of the knot then its time to address this.

Otherwise learn to tie the knots properly.

 

If its not the knot, suggest up the # and/or add a shock leader (which is how I solved the very problem or whippy cast braid breakage)