i have used 2400 almost exclusively until now, when someone pointed out that pressures are lower in these loadings (easier for my fiancee to shoot).
You are confusing pressure with recoil - two often unrelated things. If you want lower recoil, then faster burning powders, like many of the shotgun powders, will work great at reducing recoil. This is because the weight of the powder charge is lower with the shotgun powder. But if you want the same velocities as you got with 2400, pressures will be higher with SG powders and you may not be able to reach the same velocities safely.
Traditional shotgun powders like BlueDot, RedDot, etc. work
very well with jacketed bullets - loading manuals list scores of loads for them. And they
do not need heavy crimps or tight bullet pull - it is the slow powders like H110 and AA1680 that need those loading parameters. Most SG powders are very easy to ignite and are often used in cartridges which do not allow heavy crimping, like the .38 Super, .45 WinMag and .45ACP. Some SG powders will even give velocities approaching those of slow "handgun" powders like H110 - but their use is usually driven by a search for a low recoil, low cost load. There is nothing wrong with your choice of Longshot as long as you follow proven loading guidelines.
BTW, cast bullet loads usually have lower pressures due to the softer bullets which have much less bore friction than jacketed bullets. It has nothing directly to do with burn rates.....
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