I'm not a fan of porting on guns to be used for self defense. Porting pronounces muzzle flash and blast neither of which are particularly desireable features for a self defense weapon. More importantly though, if you must fire the gun from retention, you'll likely be blowing hot gas and burning powder straight up into your own face, something that will likely be quite "distracting" to say the least.
Smith, and Wesson, and Me. -H. Callahan
Well waddaya know, one buwwet weft! -E. Fudd
All bad precedents begin as justifiable measures. -J. Caesar