Violent crime has been declining since the 70's, a 40% decline I believe, and gun related crime is down in 2013 from 2012
Murder, by State and Type of Weapon, 2013 (FBI)
Total murders...................... 12,253
Handguns............................ 5,782 (47.2%)
Firearms (type unknown)............. 2,079 (17.0%)
Clubs, rope, fire, etc.............. 1,622 (13.2%)
Knives and other cutting weapons.... 1,490 (12.2%)
Hands, fists, feet.................... 687 (5.6%)
Shotguns.............................. 308 (2.5%)
Rifles................................ 285 (2.3%)
2012 and 2010, for comparison:
Murder, by State and Type of Weapon, 2012 (FBI)
Total murders...................... 12,711
Handguns............................ 8,813 (49.9%)
Firearms (type unknown)............. 1,848 (14.5%)
Clubs, rope, fire, etc.............. 1,637 (12.9%)
Knives and other cutting weapons.... 1,583 (12.5%)
Hands, fists, feet.................... 678 (5.3%)
Rifles................................ 320 (2.5%)
Shotguns.............................. 302 (2.4%)
Murder, by State and Types of Weapons, 2010 (FBI)
Total murders...........................12,996
Handguns.................................6,009 (46.2%)
Firearms (type unknown)..................2,035 (15.7%)
Clubs, rope, fire, etc...................1,772 (13.6%)
Edged weapons............................1,704 (13.1%)
Hands, feet, etc...........................745 (5.7%)
Shotguns...................................373 (2.9%)
Rifles.....................................358 (2.8%)
The 9-year trend in rifle homicides, 2005-2013:
2005: 442
2006: 436
2007: 450
2008: 375
2009: 348
2010: 358
2011: 323
2012: 302
2013: 285
So I don't see the "more guns=more crimes" assertion, unless I'm missing something here.
I think I'll believe the stats compiled by the FBI over a Stanford prof.