A 300 Win mag is not a bad kicker. If you are shooting a 50 ML and not having problems then you will be fine with the 300.

IMHO if you need a brake to shoot the rifle then you are shooting too much gun and need to step down until you are comfortable.

Do you really want to wear ear muffs while you are out in the field hunting?

Besides a brake there are many many options that will allow you to reduce recoil and not get the added noise and muzzle blast assciated with a brake.

Such as a good recoil pad like Simms.

For sighting in and practice off the bench there are a number of rests that you can use like the Led Sled from Caldwell.
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=152664

There are also a number of slip on recoil shields that you can wear while sighting in your rifle that take a bunch of the recoil away from your shoulde; Such as those made by PAST.
http://www.midwayusa.com/ebrowse.exe/browse?tabid=4&categoryid=9210&categorystr ing=655***688***

When it comes time for extended range sessions Bigbulls is right, the past pads are a great way to go...

Thanks for the input everyone. I'm new to HN.com, but I like getting all of the information & opinions, which definitely helps when you're deciding how your hard-earned money is going to be spent.