Looks like at least one crescent gouge which has then also scraped the skin. The marks next to it have also scraped the skin in the same manner but dont form a clear cresent. There is a indentation which is not easy to make out on the inside of her index finger / thumb span.
That IS Sheila's right hand, is it not? I'm just wondering how, if she was busy shooting people, with the gun in her right hand, how anyone would have been able to inflict wounds on her hands with a rifle's length between them. Had there been some sort of fisticuffs fight sans rifle, I imagine she could have been overcome before she reached for the rifle. However, it's not impossible, IF those marks are wounds, that she may have struggled briefly with Jeremy before he shot her.