Looks like they did it for a reason. Email from Hornady.
"When most manufactures of these types of cartridges work up loads that are exceeding the 50,000 psi range, they are going to want a primer cup that will be able to handle these pressures. We designed the cartridge cases with the LR primers to avoid any issues with the primers piercing during the firing of the cartridge. You would not want to use a LP primer on a cartridge case that has a LR primer pocket in it. This would allow the primer to seat to deep in the pocket and possibly give you ignition issues. Thanks"
I've known this for as long as Star Line has made brass and it is only a problem, if you have an over length firing pin. I didn't bring this up in my first response because I didn't think that you would understand. Most people have been useing LP primers and have zero issues. Only a manufacturer that has Ammo shot in all types of revolvers should even have a concern. You will not have a problem with LP primers at even higher pressure if your firing pin dimensions are correct.
But carry on.
