my brother has a 7 mag rifle barrel, he is thinking of having it shortened to 15 inches,and instaling a muzzle tamer brake.
Does anyone have any experence with this caliber ? any thoughts or load data for 15 inch barrel?

Honistly, I think you would do just as well with a 280 AI. I have an Encore rifle in 7mm Rem Mag. It is going to cost you 200-300 to cut down the barrel and put a break on it. You could buy a new one from MGM for that price!! JMHO...

My 7mm Rem Mag shoots a 162 SpBt at 3000 FPS. that means is should shoot a 162 out of a 15in barrel at ruffly 2700 FPS. My 270 short-gun shoots a 130 at 2800 fps. I don't know if this helps or not, I just wanted to throw it out there.

There is a reason you havent seen a 7 mag pistiol barrel. It has more capacity that could be used in that length of a barrel. I like the 30-06 based rifle cartrages but I try to stay at no more capacity than the 308 based cartrages in a pistol length barrel. You probably wouldnt get any better results from a 7 mag than a 7mm-08 or a 280.

If you do it report your findings!! I would be interested in your results.

Here is one you may not have considered...

http://reedercustomguns.com/information/GNR_cartridges.htm

This is our new 280 GNR cartridge. We recently did the testing on this one is Africa on 350 pound to 500 pound animals and it took them with one shot in every case. Basically it is the 405 case necked to 7mm. This one equals the 280 Ackley Improved. Dies and data are available.

Is your brother a reloader or will he be using factory ammo?

I have a 15 inch 7mm Mag barrel. I bought it from a guy at a gun show. It is a boomer! I haven't taken time to test it out yet. Right now I'm using the same load as in my rifle.

ernie
my brother is a reloader .he has other barrels 308 270 30-30 243.
he has the 7 mag rifle barrel and was wondering how it would do as a pistol. we figured someone would have a barrel here and would have some imput.

As some have mentioned my preferred head size for the Encore is 308 Win/30-06. In 7mm my fav would be the 280AI.
That being said, the 7mm RM will shoot great in the Encore (if you have a solid barrel), but you must remember that you cannot run it to the same level/pressure that he could in a bolt action gun. Have him use the same powders that he likes in the 7RM in rifle length. If he is using the slowest powder listed for the bullet weight, he may consider going to the next faster powder in that brand.
I wouldn't encourage the TC brake. There are some others out there that do a lot better job. Holland's Radial brake is superb. 541.439.5155 Several here use Holland's radial besides my self and can confirm my words.
Also, he might consider cutting the barrel at 16" - 17" instead of 15. Lot of powder there for 15" barrel-Just some thoughts.
The other question is what bullet weight is he considering?