I've used the Lumenocks with my M380 & 405 and BD400. No greater stress that I know of against 443-505 g arrows. 290# against a 446,486 & 505 g arrows is likely the greatest instantaneous force against any xbow arrow's nock. . I use 3 Lumenoks for all my practice - 100's of shots each. No apparent stress. No crack lines, apparent wear, etc.