Its fine right? When i got my 19's off ebay 3 had cracked pintles. Looking into the manifold, there is really no reason to have them except to hold the o-ring....
has anyone ever ran into a problem not using them?
I'd run pintle caps. They help protect the pin from blowback and fogging. You can get them piece-meal at the parts stores for less than 3 bucks a kit (per injector) or there's an ebay guy that sells a kit for all the injectors for under 20 bucks. I need to get one of these myself.