You might go the other way - rifle primers in pistols - but if you're loading standard - to - hot rifle loads, I wouldn't use a pistol primer. The difference, if I remember correctly, is that the rifle primers are made much tougher, to withstand the much higher pressures in a rifle. So a rifle primer in a pistol might not even fire (especially if your trick titanium firing pin can't hit hard enough to even dimple it), and a pistol primer in a rifle would likely rupture.
I heard an amusing story about the Walther P-38. The P-38 was the first mass-produced DA/SA; and was made by the Germans because the Luger was so expensive to make. It also had the first floating firing pin - the firing pin didn't reach all the way from the hammer to the primer; the hammer gave it a good swat and it flew forward until it struck the primer. A good safety feature on something that could be carried safety-off and hammer-down on a loaded round; otherwise, if you dropped it and it landed on the hammer, it would go-off and shoot straight back up at you.
The problem was that German officers were reloading their P-38's from boxes of SMG ammo. SMG's fired from the open bolt, and as a result they hit their primers a real good hefty whack; so the SMG ammo was manufactured with very tough primers, the better to resist piercing. Striker-fired Lugers had no problem with this - but the floating firing pins in the P-38's couldn't hit the SMG primers hard enough to set them off.
My heart bleeds for the poor Germans who found this out the hard way...