I shoot quite a few "Overbore" cartridges, and for me, there are many "holes" in the H1000 to 20N29 range. I have (in no particular order of burn rate):
Re25
Re50
H1000
Retumbo
H50BMG
US869
H570, H5010 and H870 (all obsolete)
20N29
There are many cases where you can only go to 90-95% case capacity, or you run out of space. Of course accuracy is paramount, but my "ideal" powder is:
- spherical (less abrasive on the throat, easier to meter, most dense);
- fills the case (or is slightly conpressed) at max pressure; and
- is accurate.
Temperature stability is less of a factor for me.
H870 was a winner in all three categories for quite a few cartridges, but is now gone. I held out hope for US869: it's spherical; a bit slower than H870 (comparable to H50BMG in the catridges I've used it in); and very dense, but not the most accurate for me to date.
What I'd really like is a powder as slow as 20N29 (next to charcoal in burn rate), but as dense as US869.
That's not Re33, but with it's density and burn rate, it's at least worth a try of one pound in my mind.