No, tape the outside.
I would take Pics but I was at work. Now Im at school.
Step by step best to my ability
1. remove barrel
2. locate detent
3. cut piece of 3m double sided foam tape or similar (YMMV), 1/8" wide, 3/8" ish long
4. place 3m tape on backside of detent (the part that's on the outside of the barrel, furthest from the barrel O-ring.
5. place square of scotch tape roughly 3/8" x 3/8" in size over foam piece/detent, ensure good adhesion. (this holds the foam in and provides backboard to make detent stiffer.)
6. Insert barrel
7. shoot neighbors garage.
Best way I can think to test is get paint just small enough to roll out of barrel. And do the shake test. See if any paint makes it past the detent and just rolls out.
Its easy to tell with qloader or other force feed.
Let it feed. Aim the barrel down. Paint rolls out. Try something else.