I've purchased several P360's and they all come with metal bushings that don't match the parts list. The parts list describes 2 bushings (15-416400 .5" for wood & 12-408400 .156" for metal) Instead they come with a single 5/8" bushing. I think the manufacturer just assumes you will cut it to the proper length. That's what I did. You can compress the spring, but then it is rather difficult to insert and remove the "E" ring. I just cut mine to 1/2" and it's much easier.
According to the instructions, if you have P360 questions you can call their support hotline:
800-230-P360 (M-F 8-5 MST)