velocity difference/ported Shield vs non ported

[Steve912]

Where did you get that graph?

I've tried looking on the internet for such a comparison, but found basically nothing.

Gun Digest Dot Com, "How Greatly Does A Ported Barrel Reduce Recoil?".

 

[OKFC05]

To those who posted that ports are for BUG competition,
Non-IDPA-Legal Features and Modifications for All Divisions The following features and modifications are not allowed in any division unless otherwise specifically allowed in the rulebook. A. Compensators of any type including hybrid or ported barrels.
https://www.idpa.com/wp-content/themes/idpa/assets/match-files/2017_Rule_Book.pdf