You can't use .38 S&W in a .38 Spl./.357 Mag. chambered gun.
The .38 S&W has a large case and won't fit into the .38 Spl. chamber.
The .38 Spl. was, effectively, a dead-end cartridge developmentally.
When S&W developed the .38 Spl. to provide a round with great power than the then military standard .38 Long Colt, they started with the Long Colt case and lengthened it so that it would hold more powder.
You're best off handloading low powered ammunition, as .38 Long and .38 Short Colt (which was developed into the .38 Long Colt) aren't widely available anymore.
But, since you don't have a press, your very best bet is to look for low-power 148-gr. wad cutter.
A range I used to go to here in Virginia also carried a line of 110-gr. lead reloads that we used to introduce complete newbies to shooting. I THINK the manufacturer was CP--Competition Proven ammo.