Freddy,
I just looked at Barne's website to be certain what an XLC was. They are not listed, perhaps they are no longer available? If you have some I believe they would react similarly to moly coated bullets IIRC. I did try some moly'ed 140 nos bt with the 284 and RL-17.(23" barrel) OAL was 3.050"
58 gr 3250
58.5 3275
59 was showing some signs of pressure
If you can get some RL-17 I'd start with 55 grs and work up in 1/2 gr increments.
FYI as a comparison, I just checked and I still have a few 140 moly'ed TSX loaded with 56 gr of H4350, vel 2985 fps
Hope that helps
