According to the gun fit chart that I have from Galco, that holster is compatible with Crimson Trace Laser Grips for the S&W J-frame 340. As far as concealing well under a T-shirt, I don't know. Since this is an OWB holster,you will probably have to have a very big,baggy,long shirt to conceal well.
Here is the link to their gun fit chart. It is very slow loading.
http://www.usgalco.com/GunFit/FitChart.xls
Here is the link to their gun fit chart. It is very slow loading.
http://www.usgalco.com/GunFit/FitChart.xls