There is little data to reference at this point. Determined by comparisons and now by testing that RL-33 is slower than Retumbo for the 7 Rem Mag, 257 weatherby and 6mm-284. With all three rifles didn't make any changes other than switching powder. Used the same brass, primers, bullets, seating depth, neck tension etc. --------------------- 7 Rem Mag: 24" Rem barrel, moly coated 162 A-max seated .010" into rifling. Original load: 72 gr of Retumbo 2975 fps RL-33: starting load 76 gr vel 2837 Unfortunately the chrono had to be adjusted, shot without it till they had a ceasefire. worked up to 79 gr for vel of 3000 for very small gain over Retumbo 80 grs showed a hint of lift and a small shiny spot on casehead. I used a bullet seating comparitor and noticed that even with the use of a drop tube the powder was filling the case. 79 gr and up caused the OAL to lengthen over .010", enough so the bullet wouldn't fit into magazine. I can see why Alliant only mentioned a load for the 175 gr bullet. ---------------------------------- 257 Weatherby: 28" #5 fluted SS Lilja 3 groove barrel, moly coated 110 accubond, .015" off rifling. Original load 75.5 gr of RL-25 vel 3615 fps RL-33 starting load 76 gr for vel of 3318 jumped to 80 gr 3432 fps 81 gr 3525 82 gr 3559 No signs of pressure what so ever. There is still some room for powder, will be trying that in the future. ----------------- 6mm-284: 28" SS Bartlein 5R barrel 1 in 7.5 twist Original load: 58 gr of Retumbo, 105 Berger target hybrid seated .065" off rifling vel 3307 fps RL-33: starting load 58 gr vel 3074 jumped to 61 grs vel 3274 62 grs vel 3335 No signs of pressure, believe can add more powder. ------------ Now for the most interesting part: I didn't pay much attention to the 7 mag as I shot at different targets. Afterwards I saw the POI was almost identical. Hmmm that's interesting I thought. With the 257 Roy and the 6mm-284 I shot at the same target for each rifle. In both cases the bullets went to the same POI! The Roy made a nice 1/2" cluster at 100 yds. The 6mm-284 with one bullet lumbering along at 3074 and the upper end loads to 3335 shot a very tiny cluster with several in the exact same hole! In my 30 plus years of handloading I have never seen this happen. I would say one rifle doing this is just a rare event. To see three rifles do this, it isn't a coincidence. I won't be shooting for several days. I want to continue with the 257 and the 6mm-284 to see what happens first, pressure or running out of powder space. I'll report back soon.