I'm in the same boat, very little data from rifles, most is from 10-14" barrels, but that really is no problem. You can use the pistol load data, pressures will be the same, your longer barrel will just add 100-150 fps over the singleshot pistol. If the data you see is from a revolver then you'll gain another 150-200 fps for the lack of a cylinder gap. So your rifle may produce as much as 400 fps more than a revolver using the same data. But really, velocities vary even if your rifle were the same as that used by the data source, only a chronograph will tell you what those loads do from your rifle. Of course you should always start light and work up to your loads but basically, if the data is safe in a pistol it will be safe in your rifle, but faster. That's not a bad thing is it?
