I wonder if that actually means 100 bullets shot, and 1 kill resulting or if it means '100 people shot' and 'only 1 killed'. Just interpreting a different way. Wonder if she just incapacitates and only kills when she needs to...
For a support gunner, 1 kill for every 100 shots isn't necessarily bad. A support gunner's job is primarily suppression so if the enemy is sticking their heads out long enough to get hit, the support gunner either isn't doing their job right or doing an AMAZING job.