Carbon Impact I think are the ones that make the weight tubes. get the yellow ones - 3 grains per inch. If your arrows are 30" you add 90 grinas with NO impact on spine. Your setup will shoot slower, but insignificant out to 20-25 yards anyway and once you reset your pins it won't be an issue.

As for broadheads ... use a sharp one, place it in the lungs and you'll kill your elk, and it don't matter if its fixed or one piece Zwickey design or mechnical.

IF you don't put your arrow into the lungs .... then you'll have problems on every count from KE to arrow weight to broadhead type.

Like these ...

http://www.carbonexpressarrows.com/a...ht_tubes.shtml

try EBAY and shop around. I bought about 45 boxes (dozen per box) at a clearance sale at Bass Pro last fall for $5 a box. Archery shops sell them for $1 a tube. Get yellow - 3 grains per inch .. I think the clear ones are only 1 grain per inch ....