Here is some chrono data with a Kahr PM9, which has a shorter barrel than the Shield:

http://www.ar15.com/mobile/topic.html?b=5&f=20&t=124484




This is an excellent comparison of shooting the Federal HST 124 standard pressure out of various lengths of Glocks. The 147 grain should be similar in results, or actually lose a bit less:

124 Grain Federal HST JHP Chronographed Through A Glock 17L, 34, 17, 19, 26 - YouTube

The loss between the longest barrel Glock 17L and the Glock 26 was just 80fps.