weights.

[oldgun]

a ? on weights?
I,m new at trad. and have been shooting 125gr. heads what is the advantage of shooting the heavier gr. heads like 350 and so forth? And are they usually a two blade? thanks.

[overbo]

Dr Ashby did a study of high % Front of Center arros for penatration and found a destinct advantage w/ it.Remember don't give up tunning for high % of foc.Most broadheads gain their grain weight thr adpters and are suited for screw-in type arros.

[Smallwood]

they can be two , three, or 4 bladed.
the main thing is that the heavier arrow will penetrate deeper than a lighter shaft.
example... throw a golf ball and a ping pong ball as hard as you can into a snow bank, which will penetrate deeper?
That being said, i personally think there has to be a happy medium between heavy arrows and still having an arrow with enough speed. I like the 9 to 10 grains of arrow weight to bow poundage...
50#bow= 500grn arrow @10grns per pound.

[Pinecone]

I would encourage you to read Ashby's study and it will answer a lot of your questions.  That said, working toward the optimal set-up for your individual bow, shooting style, etc, will take some patience and tuning.  I'd recommend that you take a look at OL Adcock's site on arrow tuning to enhance your knowledge.
By way of reference, I generally shoot 45#-47# bows @ my 27" draw.  My arrows weigh about 490 grains...with 220 grains of that up front.  I have shot completely through everything from mature mulies to javelina...with lots of critters in between.  Years of this kind of performance have made me a believer in high FOC arrows.

Claudia