Does anyone have any experience or published data loading HS-6 with plated 124gr 9mm's? My Lyman manual calls for 5.8 gr starting
with 124 FMJs, but I can't find any data for plated bullets. Also don't know OAL.  I know that most plated bullets get loaded at cast bullet loads, but I've
heard that Berry's can be loaded to low to mid range FMJ loads due to thicker plating. Looked all over the web for data and can't find anything.

try hodgdons website
http://data.hodgdon.com/cartridge_load.asp

125 GR. LCN  Hodgdon  HS-6  .356"  1.125"  5.9  1023  24,400 CUP  6.6  1124  30,700 CUP    
125 GR. SIE FMJ  Hodgdon  HS-6  .355"  1.090"  6.4  1131  25,600 CUP  6.8  1169  27,100 CUP

John,
I looked on Hodgdon's site. Thank you for the data; the 5.9 gr powder charge is going to be my starting load.Berry's HPs are shorter than the RNs or FMJs and I don't know what the proper OAL is supposed to be on a completed round.

The way I set my COAL is as long as possible while still feeding from the mag, and not having the bullet contacting the rifling of the barrel, as in they should cycle flawlessly. The shorter you go, the higher pressure the round will be under, especially the 9mm, which is a compressed round to begin with

Iirc the book coal for the 9mm Luger is 1.169. With the 124 rnfp Berry's in my once fired rp brass the bullet was just barely in the case. I seated it deeper to give it some stability. I ended up seated to 1.146. I know others who seat to 1.150 with good results.

I am using bullseye so can't help with the powder.