My experience.....Last year, my friend, his dad and I went to hunt whitetails in Kansas, which is about 12-15 hrs away (driving). I took an extra rifle just in case. When we arrived, unloaded our stuff, we went to check our rifles. My friends dad's gun, a 7mmRM would not shot worth crap and was all over the place. I offered my extra rifle, a 270. Turns out, he was the only one to kill a nice whitetail with my gun. I was proud too, as he was using my handloads developed for that gun.
We were all glad I brought an extra along and that he was able to use it successfully.
Bottom line, for an away hunt, costing some bucks, I will always have an extra just in case.
thanks,
Deerandduck