Lonny, the 41s are the military equivalent of small rifle primers. You'll find the cups are more rigid than their #400 brother. You can load them in anything that uses a srp provided the gun you're shooting them in exerts enough pressure from the hammer strike to set them off. Their intended use is for semi or full auto guns with floating firing pins to avoid slam fires. From what I've read from some of you H&R shooters about light strikes I would have to wonder just how well they would work for you in that platform. If they don't work for you or you would rather have 400s I'm not far away and would trade.
