WE say explode and grenade a lot, but the reality is that while it does sometimes happen its quite rare IF the gun is fired with loads over its rated strength. What usually happens is something breaks. Cracks. bulges stretches, rarely "explodes".
Now I'm talking about shooting over pressure loads, NOT EXTREME overloads. SAAMI specs .38Spl +p as 15% higher pressure than standard loads. A non +p rated gun MAY survive a lot of +p ammo, OR it may have some kind of failure. It RARELY grenades. However, something like a double charge is a drastically different matter!
XTP is Hornady's name for a given bullet. You need to check what the pressure of the load is. If its standard .38SPL with a good bullet it should be ok. If its higher (such as +p) then its PROBABLY too much and not a good idea to use it.
And, as far as "
a loaded gun!" I can't see that. All I can see is case RIMS so it MIGHT have loaded ammo, or it might not...
Now, if there was a pic of the front of the cylinder, that would be another matter.