I shot it the other day so I cleaned it thoroughly. It may have been some stuff in breech plug who knows?? I ran a dry patch down it before I loaded it and went hunting the day before this happened. I left gun in my truck loaded and went hunting yesterday when this happened. It could have had some condensationdevelop?? Never happened to me before but to not be able to seat another sabot for a follow up shot is not good. I use TC shockwave superglides.