I am convinced my 44 mag is a Microgroove barrel, it has 12 lands and grooves, grooves are SHALLOW, it won't shoot cast worth a hoot above 1300 fps. There are some exceptions to this....
My molds drop .430 bullets, everything I have ever read says microgroove rifling needs .002 over groove diameter.
The only cast bullet with a gas check I have shot is a Lyman a friend here sent me a sample of, it shot ok, but at full velocity was 4" at 65 yards. Not exciting, but better than most others I have tried.
The Magnus Bullet Co. 300 grainer shot a bit over 1400 fps into a groups of 1.25" at 65 yards, I was impressed.
Having shot two deer last year with a 265 grian plain base bullet at 1275 fps, I'm not convinced that high velocity, particularly with a 44 Mag is a Grail that should be so heavily sought after. As the Dave Scovill, editor of Handlaoder magazine and cast bullet afficando extrodinaire told me in a conversation about the 44 and cast bullets and velocity and Handis.........A 250 grain bullet at 1275 fps will shoot through any deer in Alabama.........I went out and proved him right.....twice over.
My favorite plinker is Lee's 200 RF pushed with 8.3 grains of Blue Dot for a nice soft 830 fps. Shoots 1" at 50 yards all day, monotonously :grin: