100 yards is pretty much the standard for moa guarantees. beyond 100 yards many other factors weigh in besides the accuracy of the rifle. My factory barreled action will shoot well, but not to the level of a Tac-Ops rifle. And there is a huge difference between 1/4moa and 1moa especially at mid-long range.1/2" at what range? cause some factory rifle can also do that, its just if you get luck or not to get one of those. the end result is if the rifle can shoot better than factory one, the custom will usually guaranteed that, but if your factory rifle can shoot 1moa or less than i don't think you need to go custom. of course there is also the bling, and smoother functionality that come with custom. so in the end it will depend if its worthy to you or not
Yes-- He has made left handed models