My friend and I,using the same gun and same loads. With the same bullets were using that 209 bh plug. We were chasing groups all morning. The weekend before I had belmouthed the bh209 breach plug and emailed ssk and they sent me a new one. When I was shooting this time I brought my calipers with me and noticed that the mouth of the new plug was opening up, as well as my friends. We found all the melted or half ones during those shots. When we switched to the cva 209 plug we never found a melted one and our groups got better. My friend got a 3/4 in groups with his and I was stacking with mine. I don't know, or wouldn't think that plug would have anything to do with the melting but it was a variable that both of us changed.