OK, here's what I have:

The bullet is taking 0.00126 seconds to accelerate (avg) down the barrel and the rifle is traveling back at a 16.139 feet per second. This equates to about about 226 G's of acceleration into your shoulder. Oh ya, it's attempting to compress your shoulder about 1.8 feet without any friction. Taking into consideration friction (prone or bench on bags), you are probably still looking at approx 1.4 feet of compression. If we estimate a 20% decrease in recoil with the break, you have approx 1 foot of compression.

These are approximates, and if someone sees errors in the math, please let me know. I can re-run the numbers. The G's and compression numbers are pretty close though. Ya, with that light a gun for that caliber, you are going to want a very efficient break. I'm not surprised it left a bruise and marks.