If I only used 5-6 rounds, I had good results. Put a total of 200 round downrange. When I switched back to brass, all of my loading problems and FTFs were gone
You likely need to clean your mags. I've found there is a bit more friction with the steel cases than brass and this makes it much more sensitive to fouling in the mag. I consider the steel cased ammo a good test of your gun's operating margins, if it works with brass but not steel, IMHO you've got problems lurking that should be fixed.
My guns are fine with steel cased ammo, a few have needed a bit of tweaking, one AR had an out of spec extractor that was fine with brass but not the steel cases. No issues since I replaced it. A few mags have needed some interior smoothing, again brass ammo hid the issue.
Only my Kel-Tec P3AT have I been unable to make work with steel cased ammo, My Ruger LCP and S&W Bodyguard 380 have no issues with it so they quickly replaced the P3AT as my minimal clothing carry as I feel the P3AT was just too close the edge of not working to really trust it, but when it was all I had it was better than nothing and I only will carry brass cased ammo.
Ain't much of a gun if the steel cased ammo breaks it! Get a brass and a steel empty and crush the case mouths. I think you'll find the steel deforms much easier than the brass.
These days if I'm not shooting my reloads its some brand of steel cased ammo. The price is compelling and its more than accurate enough for the steel plate shooting I usually do where the targets are trivial to hit if you go slow, the challenge is going fast from target to target. In this case "quantity has a quality of its very own"