If that's all you have then that's what you will have to use. Unlike LP and LR primers SP and SR primers are exactly the same height. They will fit physically but of course you should use all the normal precautions when working up a new load. Depending upon the manufacturer the SR primers may be a little hotter than the SPM primers you now use. Like said above, if you own a revolver that has a light strike spring for the hammer you may not be able to set off the SR primer. If they do work you're alright. Make up a small test batch and let us know how they work out.