Oh boy!
Here I go...
I'm going to disagree with everyone on this.
If you are loading light to middle of the road loads, and loading just for fun shooting, go ahead and use them. Now, if you are one who believes that all data in the reloading manuals (and on my pages) is 65% reduced...then you are going to have a problem.
For all practical purposes, for tin can killing, it really makes no differenece if they are rifle, or pistol, or magnum or regular, as long as they are the right diameter.
How old is "old"? I have some primers from the late '60's and early '70's that are still totally reliable.