So I was looking into turning some factory produced birdshot rounds, either Federal target or Remington gun club, into slugs. In researching whether this was possible, safe, effective, and/or practical I found many different answers. Some people said it was unsafe and I would lose a finger or worse, some people said they had been doing it for years and it was pretty safe to do. Putting aside the dangers involved, as well as the tools, recipes, and components required to properly do so, I have a couple of physics/pressure related questions. 1a. If I reduced the payload (but use the same type of shot, ie swapped out #8 shot for #2 shot) what effect would it have? 1b. Would reducing the payload increase the speed at which the payload travels? 1c. Would reducing the payload increase or decrease the pressure? 1d. Is there any danger in reducing the payload of a factory produced shotshell while keeping everything else unchanged? 2a. If I swapped out one payload for a payload of a different type (keeping the payload weight the same or less) what effect would this have? (ie bird shot to buck shot or slug, buckshot to bird shot or slug, or slug to bird shot or buck shot) 2b. I've read that if I put a slug in place of birdshot I would increase the pressure on the round/in the barrel, is this true? 2c. If true, why? Is this due to the fact that the slug generates more friction as it travels through the bore, is this due to the density of the payload, is this due to the powder burn rate for slugs, bird shot, and buckshot being different, or is there something else I am missing? I have a couple more questions but for the moment I am unable to clearly articulate them. Any answers would help, answers from those who have done this before more then from those who haven't. I'm looking for something more then, "your should be ok" but less then "the internal pressure will increase 2.5 times based on the . . . just divide the density of the payload by the weight of the powder and you will be ok". The first I've heard already and the second will only cause headaches. My level of technical understanding is limited, but honestly, any answer, be it overly complicated or simplified to the point of absurdity will be appreciated. Thanks for your time, and remember, the only time a firearm should be considered safe is when it is directly under your control.