If you're looking to get a bushing number from PW or Hornady for Promo loads, they won't give you one and Alliant won't either. I e-mailed Alliant and phoned their Tech Support number to get bushing numbers for a Pacific 366 loader and they said that due to the variation in weights between batches, to use an "approximate" equivalent of Red Dot. Not the sort of technical help I was hoping for, so I went to the Hornady chart, got the bushings for Red Dot that corresponded to the weights I wanted, and then weighed the charges of Promo. They were close, but it's ALWAYS best to weigh powder charges even if the weights are published.
I load Promo powder and will agree that 20 grains is rather "zippy". I load my 1 oz loads using 18 grains of promo. Works great. I have numerous Hornady bushings but as was stated the Promo powder does vary and a scale should be used. I have a number of bushings that either are factory or were reamed by myself to throw various weights of powder. The Hornady factory bushing #441 throws 18.5 grains of Promo. The #438 throws 18.2 grains. The #459 throws 20 grains. Hope this helps. Ed
esoxhunter gave you the info I was going to offer. I run MEC, but measured my bushing's ID to give you an idea where to start. Height on MEC's bushings is .991, and I think most others are close to that. I used Hornady bushings in my old TEXAN loaders years ago, so all are similar.
Here's my results with Promo, which I'm loading right now under 1 oz loads in both TG hulls and AAHS.
Bushing #32 I.D. - .451 - 18.2 gr Promo
Bushing #33 I.D. - .457 - 18.7 gr Promo
Bushing #34 I.D. - .467 - 19.2 gr Promo
What you really need is a good selection of bushings in the range of 430-470 in 0.005" increments. What you are about to find out is that PROMO has significant variations in densities from lot to lot and that is why you don't usually find the data you are seeking in a bushing chart. So if you managed to get your desired charge weight with a 441 bushing on a particular lot of PROMO it might be +/- 0.5g different with the next jug of powder. Don't worry about the bushing number so much as what your scale is telling you.
Good news is that bushings are cheap and readily available from outfits like Midway or even direct from Hornady. You need a good set anyway so that you use a wide variety of powders.