Used them for years
Speer plastic training ammo is great for garage practice. When I lived in a house without a garage, I waited until wife was out with the children and shot down the hallway.
You will need a good backstop - ideally of soft rags as you can reuse the bullet (black) part over and over. All of my Speer .38 bullets have a shoulder and you push them by hand to "seat" against the shoulder.
Pop the spent primer out with an icepick. I use a Lee Auto Prime (hand held one) to seat the fresh primers as I found the case mouth was digging into my hand which did not feel very good. Using the correct shellplate, the Lee is perfect for this function. The hole in the shellplate is large enough to allow the large pistol primers to pass through just fine.
Make no mistake, at close range this round is dangerous and will definitely put a whelp on a person if it hits them. Accurate for me up to about 5 yards.
If you buy the .45 version it is just the projectile - you use your same brass as for real bullets. You will need to enlarge the primer flash hole to prevent primer "set back", especially in revolvers.
John
Charlotte, NC