lcq,
I use GS Custom extensively in my .308Win, which gets used a lot as a rental rifle. They turn the .308Win into a different beast, firing the 130gr projectile in the 3000fps range. They will knock down most on the plains game list. A close friend of mine has even reported to me that he had a complete pass through with the 130gr projectile on an Eland bull at 150yds.
In my opinion, they are superior to Barnes because:
1. They are produced from 100% copper, which means that they are softer and require less velocity to expand.
2. However, the quicker you drive them, the better they perform.
3. Their drive bands are a lot smaller than Barnes, so with being a softer projectile, they produce a lot less pressure, which ultimately means that you can push them harder.
4. Minimal barrel fouling.
Take Care,
Marius Goosen