In 25 years of airgunning I have never accidentally double loaded my chamber...until today. I was zeroing with 37gr Wildman slugs in my new FX King, my main pressure was higher than my regulator(125bar), so I thought I would be good to get a zero, then fill the tank and commence to sniping ground squirrels. After a couple of shots, the gun didn't fire a round and when I cocked the rifle, back pressure was released. It didn't occur to me that there was a slug stuck in the barrel. So I cocked it again, ignorant of the fact that I was was just stacking more slugs. I thought that my regulator had taken a dump on me. So I called Pyramid as that is where I bought the rifle. They sent a message to their repair/warranty department and said they would get back to me (but they still haven't). After calling them and a guy in Arvin, California who works with Utah Airguns(who it turns out is a fabulous guy and very helpful) who work, it dawned on me what my problem was. I thought I would be able to tap the slugs back out, but there was a slug at the tip of the barrel and others behind it, and they won't budge. A few hours later I got a call from the guy in Arvin and he told me the slugs would need to be mellted out of the sleeve and that it would not be a big deal. But I am not familiar enough with the workings of the gun, and I don't have a heat gun strong enough to melt lead, so I am going to have him take care of the problem. Turns out that the regulator was not set high enough for 37gr slugs and that that is why the first one got stuck and consequently others were shoved in right behind them. I had never heard of a single slug getting stuck in a barrel, so it didn't occur to me that that was the problem until it was too late, and such an issue is not mentioned in the owner's manual. In fact, in all of the years I have been into shooting I have never heard of that issue. So, this time I am a victim, next time, if it happens again, I will be a volunteer. Luckily, I had my trusty AA S410 as a back-up and it performed flawlessly(good for me, not so good for the squirrels). And btw, after re-testing my selection of pellets, the 14.3gr Crosman Premiers I have had for at least 20 years, perform every bit as well as the JSB's I have been using, and they fit in the magazine easier(I have to push the JSB's into the mag, but the Crosman's fall right in).