Bridge reset

[JP Carlin]

So i made the measurements and for what I intend on working with I have 2 pneumatics with a 1.5 inch bore and I believe an 10in stroke. I found a table giving the extending force of a pneumatic and my results are more then double what the table says so if someone could just double check my math and tell me if they have the same thing.
so force=area * psi
(3.14)(1.5in)*(60psi)=282.6lbs of force
table says that the force with this should be 106lbs

Here the link to the table I found
http://www.usfirst.org/sites/default... %20Manual.pdf

any idea on which force I should use