Sneaky,, just went threw the exact thing with the Beman mfx 340s and was very concerned as I love those shafts.. I draw 30and 1/4 from 29 in the past.and arras cut to 30.they wee a little stiff. any how as you mentioned My broadhead actually began hitting my shelf...anyway bought some new 340 installed insert 100grn and 125 point and left full length and pulling around 62 on my Morrison takedown.. yowza just what the doc ordered , nothing but knock on the way down and straight to point of aim.out to 20 yds. then swithced to my heavier limbs and yawza again at around 67 lbs...Now with these arras i got 600grn even and they are moving at 190 fps +- 1fps...I am stoked...