I have a set of TT longbow limbs that are 60# on a 19" riser.  My riser is a 17" Morrison and when I bolt the limbs down, it is no doubt way over 62#.  I backed out two turns and now its manageable, but still heavy.  Is this common?

Yes. Every inch shorter you go from the limbs rated riser length you gain roughly 1 pound. So you have went 2 inches shorter,gaining roughly 2 more pounds than what is rated. I have found TT limbs to be more like a 4 pound gain myself. Hope this helps,rat'

Also,if your draw length is more than 28" those limbs will start feeling very heavy at the end of your draw cycle. rat'

Some Morrisons are marked in the limb pocket +8 ,+9 you have to add that to poundage....if it's marked like that! You could be shooting a lot more than you think. Plus I think TT limbs are marked at the bottom of their range. Your limbs would be maxed out at 64-65 + 2 for the 17" riser! You could be at 67-68#'s!

Your TT limbs are 60#s on a 19" riser, at minimum preload...let all the way out. Add 2 lbs. when going to a 17" riser, and you are at 62#s, at min. pre load. Screw them down and you will add about a pound for each turn. So, your set up should be somewhere in the range of 62-67#s,+ -, crunching the numbers, providing similar degrees of angle between a Morrison and TT riser.

I'll bet when you screw them limbs all the way down, your bow looks fairly fast, for 62#s.  :D

Thanks guys.  Should have added it is a Gen II aluminium.  I can't find a scale but closer to 70# is what I guessed.

ron w makes a good point about the +8, or +9 marked in the limb pocket. I own one, and 40# TT limbs go out to 53#'s. I have tried several limbs with the same results.

Gen II risers are the same as ours so if rated on a 19" they gain 3-4 pounds.  The TT is rated on a 17" riser but is rated at minimum load.  So add 3 pounds for mid range and 4 pounds for the riser and you are a smoking 67 pounds.  Did I mention that TT limbs tend to run heavy also. . . LOL

Mike