Using a pair of trees or a fork, or whacking the barrel against a pole is not a random method. But it does require some sensitivity to what is happening, and some of you may not be comfortable with that. Some of us have a tendency to overthink stuff, and so it never happens.
I worked for a gunsmith in the last century who taught me many things. One day, a trap shooter brought a Pirazzi shotgun into the shop, complaining that it shot high, and he would sometimes miss more than one bird in a hundred - completely unacceptable. Don sighted down the barrel in front of the client, and proclaimed, 'sure enough, it is bent upwards. I'll fix it". While the customer was getting into his car and leaving, Don cleared off the front counter in the shop, seized the barrel by the breech end, sighted down it rolling the rib perfectly straight up, laid it against the counter, then raised it to the ceiling and brought it down hard and flat against the top of the counter. He sighted down it again, and said "there, now it's straight. Easiest hundred bucks a guy can make." The client was just leaving the parking lot.
So using his tutorial on barrel bending, when it came time to increase the elevation in my Long Land Pattern Brown Bess, having fired several balls to determine point of impact, I removed the barrel from the stock, seized it by the breech, and gave it a whack against one of the uprights to the shooting shed. I replaced the barrel, fired a few more rounds and then repeated the process a couple more times, each time increasing the bend until the Bess shot through the centre of the target. Looking down the barrel after this treatment, I could only barely see a deflection upward in the barrel, along the outside, but it was exactly the right amount, by trial and in this case, no error.
So my advice, FWIW, step out on the limb and take a chance...you will learn something no matter what happens. And don't make things more complicated than they already are.
