i have recently installed the timney ar targa short trigger and found that i needed the kns anti walk pins....the assembly is a drop in model....just take the old trigger out, remove the safety lever and install the trigger....

what i feel happens is that the fit of the timney is tight and slightly expands the lower...as far as the trigger goes, its amazing....one of the best upgrades i made to my 15-22....hope this helps...

Bob