I have tried Wipe OUt and Forrest foam, liked the wipe out much better....Have not used Knockout by Forrest....

I put a piece of 15" surgical tubing over the nipple of the Wipe out can, plug the chamber insert the tubing and give it a quick squirt, the foam will push the tubing back out of the bore and you will have a full boren of foam....

I like the Wipe Out, it's a great product...I didn't like the Forrest product...