you should not be reloading if you have to ask that question.
it was just a question that i was curious about..i wasnt trying to do anything but learn. starting to regret asking....lol
^I'm surprised this wasn't everyone's first response.^Generally not a good idea. The first thing is that large rifle primers are hard. Your 45 firing pin may only dent the primer and you'll have a FTF condition. Or end up dropping the hammer twice on each round. The load can be compensated easy enough. Drop 20% less powder in the case. Then check the FPS Work up to desired load. That's a hot Magnum Large Pistol style flash coming out of a LRP in a 45 case.
Since primers can't be returned to retail store, Advertise on Texas Gun Trader or Armslist and see if you can make a trade for large pistol ones? Thankfully primers are returning to shelves and someone may just have what you need now. Patience!