Danny,
Because of its very odd shape, the .243 wssm cartridge is notorious for feeding problems. I don't think the problem with your friend's rifle lies in the plastic mag follower, but in the inherent problems of the cartridge.
I too hate plastic parts, which is why I am dumbfounded that people run out and by brand new rifles, when they could buy the older rifles, much better built, in VG+ condition, for about half the price.
Get the full Brownell's catalogue. It is very very thick. They have hundreds of useful conversions and parts, and may have a steel replacement follower for this.
Mannyrock