The two bullets are identical except for hardness.
I have used thousands of the Cowboy #4, 12bhn bullets in my 45 ACPs. That is the only bullet I use. Absolutely no leading in any of my five 1911's ranging from a Colt Rail Gun, through a couple of Commanders, a CCO and an Officers. I seat to the crimp groove (about 1.195 oal) and of course use a taper crimp. They all feed without a problem in all five of the pistols.
I have also loaded several for 45 Colt and had good performance from them also.
A nice surprise a month of so ago. We moved last year and my garage has been packed full. Moving some things around I found 4K of them I had ordered after we moved and promptly covered up. Just like found money!