just today i went to gander mtn. and baught a paint touchup kit, and painted 2 dozen old henryettans they also had cracks in their chests. to fix the cracks i used low temp. hot glue on the inside and outside till it stuck nicely then put plenty of duct tape on the inside to reinforce them. then i got painting it took about 7 hours to glue tape and paint all of them.