Pistol primers and breech block damage?

[Fogman01]

So what do you all think the verdict on large pistol primers in a Shiloh is? I found some Rem 2 1/2 and bought some because I noticed some of the top shooters use them. I loaded a few with a manila folder wad under the primer. It still sits slightly deep though. Does a wad mitigate the "dents" or does the burn still find its way back to the block anyway? I have a lot of rifle primers so I'm not to anxious about it - I have wanted to compare LP with the LR and work up a good load for my 1877 but I don't want to damage my new rifle doing it.