ECB 3D Printing has made a replacement breech seal for the Angel paintball marker. 
 
This is made in a semi soft material that feels similar to O-ring rubber. 
 
Our breech seals are sold in pairs. There isn't any glue or adhesive on the back. You will need to use double sided tape (we use the Gorilla Glue double sided tape as it is thin and very sticky) or glue to attach these to the breech.