Benanov
PM Bomber
This is actually pretty true even generically.
If you train with an item you don't own, you don't learn as much because you don't feel the item is yours - you have to give it back.
If you train with something you own, the training will stick more for a couple of reasons - you own the item and wish to become proficient with it, and you can train any time you like (even informally) because you own the item.
(In the case of firearms, things like dry-firing with snap caps can be done in your own home.)
