Hey mate
Lots of good suggestions, one or two crazy ones!
I've also seen this happen, simply mistake, wrong size boresnake got stuck, the lad (120kg, 6'8", lock forward) gave it a really decent pull which just made it worse. Stuck as....
As per some suggestions, a really good lube with oil, allow it to soak, then with the chamber end of the snake gripped tight as in a vice, a strong bloke grips the stock at the pistol grip and forend and, with some slack in the snake, gives it one or two proper hefts. With his body weight and the shock of the snake suddenly tightening, I would be amazed if it doesn't come out.
With the example above, it took 3 or 4 good yanks before the abrasive metal pad shifted slightly (that's usually the bit that gets stuck), then one more heave ho and out it came.
Just for gods sake make sure you've got your feet positioned right, or you'll tip over with the rifle!
I would be surprised if this wasn't what a gunsmith tried first...
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