One of our sponsors (CanadaAmmo IIRC) had explained that Dominion Arms small rifle and small pistol primers were identical except for the box. I bought a case of 5,000 on sale and have been through 3,000 of them in both 9 mm Minor loads and in 223 with no issues. I plan to continue using them.
On some rifles where your load is near or over max., there may be some benefits to using dedicated small-rifle primers which may have harder cups. I think that brand-to-brand variation in hardness may exceed that between small-pistol and small-rifle primers.