A friend of mine lives in AK who has recently had surgery on his neck. He has a 416 rem mag with a muzzle break on it already but he is afraid the recoil is still going to be too much. He was talking about getting a stock that can help reduce the recoil even more. The only one I have found is the blackhawk axiom. Has anyone used this with heavy calibers and how did it work. Is there a better chassis system or stock that can help reduce the recoil?

Also found falconstrike hydraulic recoil pad.

I'd forget the stock and focus on a new barrel in a lower recoil chambering. If he's shooting a Remington 700, I'll send him a take off barrel in 7mm Rem Mag for just the cost of shipping.

If it's a synthetic stock, take off the recoil pad and put in enough buckshot to get the weight he needs to reduce the recoil to a mild level. Then shoot in some insulation foam to hold it in place and re-install the recoil pad.

He could use reduced Loads.

Yep,,, Load it down to 2200 fps, it will still kill anything this earth has to offer!

If it has a brake already, then the recoil should be neglible.
I had shoulder surgery, I was able to start shooting within 12 months. Yeah, it was a while before I was recoil tolerant again.
I shoot 375 Bee, 416 Rigby, Lott and a 338-416 Rigby Improved ( this is the only rifle I have braked).
I also shoot 300 mags and 338 mags unbraked.

I asked my surgeon before I started shooting, he was very positive in telling me I could start when I felt the pain was no longer an issue and to ease into it. I started my shooting off with my 222 and progressed into heavier recoiling rifles as my confidence grew.

Cheers.

Drop down to a 300 - 350 grain bullet at around 2-2,200 fps and recoil shouldn't be too bad. A recoil reducer might help but only slightly more than just adding weight. Since some injuries can be aggravated by any more shock or trauma the re-barreling option seems like the best idea. The 7mm RM can be loaded to 7x57 performance levels and have very low recoil. I also just got a shirt that has a pocket for a Shockeater pad and this helps quite a bit. The PAST and Sorbathane pads are good too, but the Shockeater had the best attenuation per thickness.