I also love shooting pins. It's different then paper. You have to take the pins off the table, not just hit them. There is a difference.
For practice I took an old swing set frame. I put some eye bolts in the top of the pins and hung them from the cross bar of the swing set frame.
The pins, per rules are spotted 16 inches a part. 36-40" High, and firing is done at 25 Feet.
So in any practice one should use those measurements. If you don't have pins to practice, make some paper targets and set them up on a target background that gives you those measurements.
However, pins don't last forever. At pin shoots many of the pins get so they wont stand up. Clubs normally discard these pins. Though they can't be used on tables, they can still be used suspended from as I mentioned above. Hanging them from an eye bolt means you can shoot them until there is nothing but splinters on the ground.
Its not hard to hit pins, but having them knocked over and spinning on the table is a different matter. You want a round that takes them off the table.
I shoot pins with a revolver. A six inch Model 27 357. I load the shells at hot 357 levels, but still bullet selection is critical.
I shoot a lot of other action pistol matches with a revolver, I got Lyman bullet 358665 which works great with speed loaders. How ever, being sort of a round nose bullet it sometimes goes through the pin with out taking them off the table. But, loading Lyman's 358477, a SWC bullet at the same velocity grabs a hold of the pin and deposits it in the next county.
45's make a great pin bullet if you get the right bullet. But in semis like the ACP the bullet shape doesn't work as well as a full wad cutter. The 45 Long Colt, with SWC's works well. It doesn't take much velocity with that 250 gr bullet. I tried them and they work. My problem is the only 45LC I have is a SSA, which makes for slow reloading if I miss.
For practice when you're alone use a shot timer to record your progress.
Like anything else, Pin Shooting takes practice, but its a heck of a lot of fun practicing.
HINT: 32 gr 204 Ruger's make lousy pin guns. They barely move the pin, but will take a big chunk out of the back of the pin.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071