I have looked around and 145 gr. is the heaviest made to fit them correctly.I usally go with heavier inserts to get more weight up front in tuning them.What I did on one set of MFX I had was to foot them with a 1" piece of 2020,and then 5/16" points fit more flush.And you can get 5/16" up to 300 grs. and many sizes inbetween.Or another method you can get broadhead adpaters and then use 11/32" points or steel broadhead adpaters and use with glue on points.There are many different combo's you can come up with.