So buying my own gear saves the government money in two ways: (1) they can buy cheaper gear for me, and (2) they're less likely to have to pay my SGLI.
SGLI is underwritten by a private insurance company. Uncle Sam is only on the hook for your $100K death gratuity payment (and funeral expenses). /casualtynerd
In the two years that I have been working in Casualty, we have not had a single (hostile) casualty report for a VBSS crew member. The guy that we did lose wishes that he had spent some of his own own money on a better life jacket.
The sailors who need the better gear are the SEALs (and they get whatever they want), and our FMF HM's. Outside of HM and SO, I can't think of a single rate that has been a combat casualty in over a year. We did have some medical corps folks get shot up, but that was not exactly "combat related".
I can say with 100% certainty that the helmet that the Marines works pretty damn well. I have had multiple PCR's over the past week were marines suffered a "gunshot wound to the head" and were treated for a "contusion and swelling around the eye". If you take an AK round to the grape, and only have a black eye and sore cheek bone, you are one lucky Mo-Fo (and you need a new helmet).