i have a vest weight from
www.weightvest.com
its adjustable 40lb max i was planning on
doing some full sprints with 10% of my
body weight in the vest.
Is it safe and will i benifit from it.
(Got to to get Faster 
hmm, I wonder about that too. Along with the weight vest idea, what about training with ankle weights - Is there any benefit from these ideas with regards to sprinting?
Weighted shorts are probably a better bet than weighted vests. I believe Remi Korchemny advocates the use of weighted shorts.
Don’t do weighted sprints. We’ve covered this many times, recently in fact. When you increase your bodyweight, it causes the hips to drop when you sprint. Use the weight vest or shorts for drills if you want, but when it comes time to sprint, do it without anything that will disrupt your mechanics.
ive never tried it, but i think running with ankle weights would really throw off your range of motion and end up deviating your proper stride…? also, wouldnt this lead to chance of injury in the hip?
i remember reading somewhere 
that muscle in the calf isnt as productive to the running motion as muscle in the upper leg, and i think a mentranone(sp)(one of those things piano players use) effect, the farther the weight is away from the axis the heavier it weighs?
ankle weights,
I am sure I have read that these are really bad for your joints (ankles and knees)