Not sure if I'm really understanding you correctly, or maybe Rod misunderstood you, but the wipe definitely just pops into place on that first ledge. You'd really have to work, fold, push, and manipulate it to go past that and have it rest against the inside face of the front cap. If you do that, you could damage the cap when the bullet goes through since the bore doesn't like to share that space with the bullet plus the wipe material that will get dragged through to some degree as it stretches around the bullet.
In other words, just make sure it stops on that first face when you pop it in. There's actually a groove for it too. Some visible threads may still be exposed on the outside when you tighten it down because there can be some variability in the rubber wipe and how well you tighten the cap. Be sure to use the tool to tighten the cap so you really capture the wipe. That final baffle, called the "cap baffle", contains the wipe on one side, and the cap contains it on other.
Let me know if you need more info!
Todd Magee
Chief Designer, Dead Air
ETA: baffle goes inside to secure the wipe: