Purchased a box of the Colibri powderless 500 fps or so and as Stein pointed out there were concerns over the bullet exiting the barrel of a long gun.
A well used 20 year old Ruger 10/22 with 10 rounds of Colibri, no issues exiting the barrel. You do have to self cycle. The sound level is like crushing a soda can.
Ineffective on squirrel at 20 and 30 yards therefore it is not going to be a raccoon solution here.
Highly inaccurate.
No squirrels were harmed in this test and good for them as so far I have found them harmless in the yard. I bet a few are a little sore about now however.