Good question! I am hesitant because I don't know how thick they are and I am have not held a pair of aluminum grips.  I emailed them and got this back:

Thank you for your interest in Hogue Grips! We appreciate
you taking the time to contact us. We do make grips for your Browning Hi Power. The Hi Power has been made since 1935 and stayed very consistent through out the years in frame size. The exception would be a BDA or BDM model, these won't fit at all. There is the occasional frame that has a
small safety lever that can make it difficult to install the grip. But
if you relieve that area on the grip, you will be just fine.

 

Interesting, because we know that there is a difference between the forged and cast frames. However, I am encouraged that they say that the grips CAN be relieved.

They look nice though (pic from the Hogue website -  click pic to enlarge):

UPDATE 12/16/2011

I got another email from Hogue which said:

I've heard from past customers before that some of our competitors don't fit quite as well as ours. However, since you have had the issue before you may want to try the rubber grips first to see if there is anything that needs to be done. It's not a large investment financially and then you would know for sure as to whether there could be a fit issue regarding those. The G10 isn't as customizable as other materials.

Interesting (!) and good advice too.