I recently purchased a new Ruger SRH in 454 Casull. I have tried winchester and starline brass with rem 7 1/2 primers and a few other small rifle primers. Seems that about one time in every cylinder full that the firing pin will strike the primer dentin it but not causing it to go off. Sometimes all six work and sometimes it may be two or three that don't work. Works every time with assorted 45 colt cases and large pistol primers. Any ideas what my problem might be?

Most likely, you need to go up one strength on the hammer spring. Pistol primers can be much softer than rifle primers and this indicates the hammer is not hitting the firing pin hard enough.

You need to have a pistol smith check the firing pin protrusion. Redhawks and Super Redhawks are notorius for having short firing pin protrusion. This condition gives the illusion of a weak mainspring and if this is the case the strongest spring in the world won't help your problem. If it is the problem Hamilton Bowen makes an extra length firing pin for both versions of the Redhawk. Or Ruger could fix the problem. I would agree with MS Hitman regarding the reason the pistol primers fired whereas the small rifle primers did not. I remeber reading an article stating that Rem 7 1/2 primers had the thickest cup of all primers.

Thanks for the advice. I have a good friend that used to be a gunsmith but he lives 1000 miles away and is very hard to reach on the phone. I will be there around Christmas so I will have him look at it then. Just thought that maybe there was a simple solution or if I needed a part I could get it so he could install it. Thanks again.

Open the cylinder cock the hammer pull the trigger and ease the hammer down, do not dry fire, while the hammer is down with the trigger pulled measure the amount the firing pin is sticking out. Go to a gun shop ask to measure one they have use same method. If you find they are the same then I would advise to replace the spring if they are not I would send it to Ruger and let them fix it.

I hope this will let you know what is wrong, if not it wont cost you anything.