New to using a smoker. I just got done with my first build, I decided on and built a double barrel smoker. Yesterday I figured I would give it a try. I wanted to start out with something a little cheap and easy so I used a 4.5 lb pork loin. When it was all said and done, the loin had a great smoke taste, but was pretty tough to chew. Just wondering what might have went wrong and what I might have done wrong. The night before I injected it with a recipe that I came up with, I then placed it in a pan (left it uncovered, which I think I probably should have covered it) and put it in the refrigerator. The next day I started up the smoker, was using charcoal and some cherry wood, got the temp up and grabbed the pork from the fridge and threw it on (but now I know I should have let it get to room temp first). I cooked it till the temp was about 150 and pulled it and let it sit for about 30-40 mins. Like I said, had a great taste but was just tough. I was able to keep the temp to 200-225 during most of it. There was a few times it did reach 300 or down to 175, but wasn't at either for very long. I don't know if it was one big mistake or several that caused this. I tried to give as much info as I could, so any advice would be helpful!