If that window is made out if the same shit on the outside of the train you're not busting anything, lol. It aint shattering. Even if you fired a gun at it best you will do is punch holes in it if its "railway" plexiglass.
You never know what motivation might accomplish.
The
one time The Bride and I took the Northeast Corridor from Rt. 128 to Philadelphia Penn Station,
we discovered why the windows on some locomotives are covered with a grid of steel bars.
A couple of rows in front of us were a few rows of Brownies - not even Girl Scouts - on a field trip.
They were of course chattering like a circus load of monkeys on meth.
Until the train was whipping at speed through salt marsh between Providence and New Haven.
I saw one or two youts on the RoW. One of them whipped a rock
(just realized it must have been a chunk of ballast) at the train.
It hit the window directly athwart some of the Brownies.
It held, but of course was shattered worse than Mick Jagger on Some Girls.
The Brownies instantly switched to screaming in mortal terror.
Once they moved to some empty seats away from the broken window,
there was no more chatter. It was probably more like this:
The steel bars are gonna be to protect engineers from stuff dropped off of bridges.
(I still remember that one night youts pushed one of the much-bigger-than-a-breadbox
parapet stones off of a Southern State Parkway overpass on Long Island
and decapitated a woman driver. Nassau PD caught them because the cops
canvassed the adjacent neighborhoods and found a house party).
If I'm battering a window with a fire extinguisher,
it's gonna be a lot more force than some yout whipping ballast.