I will hunting elk this year in Co. and have decided on using the magnus stinger broadhead. I like the extra cutting surface of the 4 blade but, I am worried that it will reduce penetration. Does anyone have any elk hunting experience with the magnus 2 blade and 4 blade heads? What is the better one to use on elk?

Split the difference and use a good 3 blade.
If you have a decently heavy arrow, penetration shouldn't be much of an issue. A hole is waaaaaaaaaaay better than a slit :-)

How heavy of a bow and arrow combo are you using?  I will probably be using the 4 blade Stingers out of a 58lb bow with 610 grain arrows for elk in Sept....unless I buy some 150 grain 2 bladers that is..  :D

Forgot to add what I'm shooting, Bob lee recurve about 55#@ may draw of 27.5. Shooting beman mfx carbons with 100gr. brass inserts, arrow weight should be around 550gr.

Elk can be tough, shot placement and penetration are the key factors.

I have seen elk killed with just about every broadhead out there but most experienced elk hunters around here shoot two blade broadheads to max the penitration.
 
Some compromise by using 4 blade heads with the bleeder blades filed down to stick out obout 1/4 inch -- theory being that it will help open up a slit to reduce shaft resistance.

I have had real good luck with the magnus two blade in the past -  but this year I will be trying out Grizzlies and heavy, extreme F.O.C. arrows as perscribed by Dr. Ashby's research.

But--I would consider the two blade Magnus Stinger with a 550 grain total arrow weight very appropriate for elk when shot from a 55# bow.
That type of a set up has killed a lot of elk over the years.

I shot a bull elk a few years back with a Magnus 4 blade head. The elk was at 28 yards, the broadhead blew right through and was laying about ten yards past where the bull had been standing. Will be using the Magnus 4 blade again this year. My bow is 62lb. so it is a little heavier than yours and my arrows weigh 550 grains.

I should add to my previous post that in my experience I've always thought that I've gotten better penetration with the Magnus 4 blade than I've gotten with various 3 blade heads. This isn't based on 5 or 6 animals, this is based on 35-40 kills on deer, bear, caribou, antelope, and a cougar.

Ks8674... the bleeders on the Stingers are pretty dang small and won't offer much resistance at all if any.

They are big enough to "releive" the slit from the main blade with a chance for improved leakage as well as slightly larger wound channel.
 

Thanks for all the info guys!!

This post sounds familiar doesn't it Charlie?     :p

I do believe I've addressed this recently.