I currently have on order a Ferguson Z58 70# at 29". I have some .340 spine carbons that I plan to shoot with 125 grain tips. My question is should I use standard aluminum inserts or should I go with brass inserts for the extra weight up front. Thanks. Mark.

there is no substitute for experimenting with most carbon shafts/arrows.  with carbons, no one can reliably tell you want will or what will not work for *you* and yer bow(s).  

so, the easy answer is to try using what you've got and play with the point weight to help get the arrow and/or bare shaft to fly best for you.  once you know what front end weight works best you can match a broadhead adapter weight to yer broadhead of choice and match the front end weight that works best for ya.

Like Rob said,you need to try them out.What I do for my carbon tuning,I tune them without gluing in the inserts.I'll take the insert and push it in with alittle saran wrap to hold the insert in snug.But you need a softer bag target not a foam target.The saran wrap holds the insert in snug and the bag target doesn't grab tight enough to pull the insert out on removal.After I have experimented and tuned them to my satisfaction,I'll then clean and prep the shafts for installing the inserts.I get my carbons tuned without gluing or using any heat on my carbons like trying to tune with a hot melt.I just don't like to apply any heat to carbons.

Thanks for the responses,  I will try my aluminum inserts and try cutting them down untill they fly good. That is a good idea to use saran wrap in the inserts, I have used it on loose fitting nocks in the past but I never thought to use it on inserts. Thanks again! Mark.