How do you know when you've hit the wall with a specific powder

[diablodawg]

Bullet is definitely out of the barrel- I have a picture of me an the gun is in battery any you can see the gas exiting the barrel; obviously behind the bullet.

Although, my ex had a SP01 with 10 lb spring that would spit hot gas if used with full power loads, so there is a pressure differential, although the bullet is already out.