FOR COMPARISON ONLY
7gr of H110 under a 55gr bullet shows a muzzle velocity of 1900fps in the .22 HORNET
You won't find low speed loads in standard .223 data, not because it can't be done, but because its not what most people are looking for, so the testers don't spend time and money doing those loads and putting them in the common data.
So, if you're going to develop short range low speed loads, you are entirely on your own and "off the map" as it were....
I did, some 50 years ago create "gallery loads" in some rifle cases using pistol powder. These loads are "tricksy" and one screw up can result in a really bad accident. So, I will not recommend it, or give the details of what I did. I will say that a double, triple (or more) overcharge of pistol powder is difficult to spot in a large rifle case, and that can result in serious damage to your gun and even to you. So don't do that!
Now, here's an alternate way of looking at it,
go to a ballistic table and see what range your load is down to 1500fps.
The 55gr Hornady SX bullet with a 3200fps muzzle velocity is down to about 1450fps at 500 yards, according to the table in their book.
You could, if you have the range, set you ballistic gel at that distance, and shoot it with full power loads to see what the bullets actually do. Few people have that option.
Or you can make a rational judgement about what you might shoot at that distance and how important expansion (and how much expansion) is required.