105s probably won't shoot well in your rifle. They likely will be too long, and won't stabilize. As to the magazine, the 788 will give you lots of room to set a bullet way out there. Much more so than other factory mags. I built my custom rifle (243) on a 788 action. I am shooting 105 Berger hybrids but have a 8 twist barrel to do it. If you are looking for a good all around bullet for your 788, try Sierra's 85 grain game king, or noslers 95 grain hunting ballistic tip.( Not the varmint bullet) Both are very accurate, and perform well on deer and other critters.
