I don't understand the pulse. What is the frequency and what is the duty cycle? 300 ms doesn't seem to be enough information (to me). Unless it is a one shot pulse of 300 ms width.
If you pulse the motor and it turns 1.25 revs, does that mean it moves from stop to some rpm and back to stop in 300 ms?
If the model turns more than the real motor, there is something wrong with either the friction or inertia in the model. I don't have a similar motor so I really can't do much in determining the constants.
It looks like 'b' in my Motor2 Matlab project is viscous friction.
I revised the project to display 'w' the total rotation and I get around 9 revolutions in 300 ms. Reduced by 10x for the gearbox, this would be about 0.9 revs. The thing is, inertia keeps it rotating. The RPM very slowly drops off. You can see this by changing the simulation run time from 0.5 sec to, say, 100 sec. You will see that it takes nearly 1 minute to stop rotating. So, we have a boatload of inertia and no friction. If 'b' in my .mat file is truly friction, and I think it is but I forget, it's set to a very small number 5x10-6.
Since I didn't know how to define a 300 ms one-shot pulse, the pulse generator sends a 300 ms pulse every 100 sec (I guess I could have chosen a bigger number) so don't simulate beyond 100 seconds without changing the generator.
Attached .zip file contains the .mat and .slx files.