When shooting .357 ammunition in either 340 model, I've found that NO grip works in mitigating recoil and increasing control so I've stuck with the OEM boot-grip knockoffs.On a side note, these grips duplicate very well the feel and size of your proposed setup. As to shooting .38 +P in these guns, I never have: it's not why I bought them.

And remember, if you want to see your T-grip again, remove it before taking the gun in for service...

Kaaskop49
Shield #5103