Check out Federal's website. They have a compare feature.
http://www.federalcartridge.com/default.asp?pg=27Sorry for the physics lecture, but here's why the "Low Recoil" loads kick less:
Federal is using lighter, faster projectiles in those "Low Recoil" loads. They have lowered the bullet weight one or two 'notches' while kicking the velocity up just enough to obtain
almost identical muzzle kinetic energy compared to the standard load.
The trick is that the lighter weight projectile has lower momentum by about 8 %. Projectile momentum (and powder charge mass) is what causes the gun to react in your hand. Remember, Newton's laws of motion pertain to conservation of MOMENTUM, not energy. (The difference is (mass x velocity) vs. (1/2 mass x velocity x velocity.) It's a good thing your gun recoils proportional to the momentum of the round and not the muzzle energy. Not many men would be able to hang onto a gun that comes back at you with 320 ft-lbs of energy!!
I'm a retired mechanical engineer and have been studying up on ballistics - exterior, & terminal - for the last few years. I got tired of reading all the B.S. in the gun mags about "energy dump", temporary stretch cavities, frangible bullets, expanding bullets, etc. The physics & medical aspects are really complex. The best references are Duncan MacPherson's (a real rocket scientist!) "Bullet Penetration - Modeling the Dynamics & the Incapacitation Resulting from Wound Trauma", and the writings of Dr. Martin Fackler - a former U.S. Army trauma surgeon.
Steve S.