I purchased the SS 3/4 to 1/2 reducer and the SS 1" coupling from McMaster to pull 1/2" couplings thru my kegs. I picked up a damaged keg to practice on before doing my good kegs (Thank God!) I pulled the 1/2" reducer thru then when I went to pull the coupling thru and the hole is a little to big. Everything I have read said the coupling should be tight in the hole. If I try to solder it now the solder will just flow thru. What might I be doing wrong?