I've been on a consuming 44 Special +P binge and have done a lot of testing in a short period of time. Some surprises and some things what I expected. All the data I am working with comes from Handloader 236 and 312 articles by Brian Pearce which contain pressure data. He refers to standard loads as level I and 22K PSI loads or less as level II and 25K PSI or less as level III. S&W 24/624 (post-WWII N-frames) and Ruger Blackhawks are both level III capable revolvers, and probably the ones that most people shooting heavy 44 special loads will be using (I would not recommend these loads in any five-chambered revolvers (including the GP100) or Colts or Colt clones). I think it is easier to just call the loads 44 SPL, 44 SPL+P, and 44 SPL+P+.
One of the surprises was that I don't like 2400, which is the "go-to classic powder" for +P and +P+ loads. I don't know if it is the batch (Nov 2009 produced Lot X) I am using or something else I don't understand, but I have a hard time believing that THIS was the powder that started the whole magnum craze and that such knowledgeable re-loaders like it. It is horribly sooty and causes at least a little leading in basically every load I try. It causes leading that the exact same batch of bullets does not cause with different powders, even when the pressures are running about the same, and it never seems to burn completely unless driven very hard. My best time with 2400 has been in small capacity rifle cartridges--32-20 in particular--and it has proven useful to me in 30-30 for reduced loads, 357 Herrett for reduced loads, and it is pretty useful in 357 magnum for both rifle and revolver. But in the 624 it just looks like after one shot that I've been shooting all day. It stains up my pants too since I am doing a lot of sitting long range shooting. I am getting the expected velocities, so it isn't bad primers or something (CCI 300 Standard Large Pistol purchased during the scare back in '08). Accuracy no better than anything else...in some cases worse. I must say I am just surprised.
Another surprise was Blue Dot. Basically it does nearly what 2400 can do velocity wise, with less powder, leading, fouling, soot, blast, noise, no pants staining, recoil, flash...etc. For the ~25 FPS difference in respective max loads the choice is obvious to me. With the MP 429244 HP (~240 grain) 12.5 grains of BD returns a consistent 1200-1225 FPS from my 6.5" S&W 624. 16.7 grains of 2400 does 1225-1250 FPS. These are both +P+ loads (to 25k PSI) based on the solid bullet, so I expect that at 15 grains less bullet weight in the hollowpoint that these are running a bit less than 25k PSI. In either case 1200 FPS is pretty solid velocity and about as far as I care to take it velocity wise. Accuracy wise the Blue Dot is about equal at short range but superior once the distance gets greater mainly because it has a smaller deviation...about 10 FPS. Once I have proven out this Blue Dot load (I am toying with charge weights between 12-12.5 to see if I can find a optimal one) I will report back on the gel-testing. Let's just say I expect outstanding results from that HP when cast from 20:1 and with 240 grains of weight behind it. Can't really think of a better whitetail load to ~100 yards.
One thing that I was expecting is excellent performance from Unique! And boy it does deliver! With pretty much every bullet I've tried it gets what I expect or better and it is clean and consistent (I am using recently manufactured Unique 2019). In fact, 8 grains with a certain batch of Arsenal 429421s delivered about a 5 FPS variation in velocity! From 7-8.5 grains Unique will push a bullet 200-255 grains 900-1100 FPS or so with good accuracy and no drama. Just a good working load and isn't too bad on the hand/wrist. Up to 8.5 grains of Unique is a +P load.
Another winner is PowerPistol. 8 grains of it will match the classic 7.5 grains Unique/429421 "Skeeter-Keith" load and do it at standard pressure so it will be safe in all good condition 44 specials. It doesn't fill but half the case however, so it is somewhat of a double charge hazard. This seems to have no effect on accuracy. Except for the freakish 8 grain load of Unique above, PowerPistol has proven to be equally accurate as Unique or any other powder.
Now in case you thought I was an Alliant partizan, Tightgroup is a fine powder for standard "target loads." Despite filling only about 1/3rd of the case (a major double charge or even triple charge hazard) it is accurate and consistent and very economical. I have the same bottle of of TG I bought 12 years ago and I still think I have about 50% of it because you use so little of it, despite having thrown so many 3-4 grains charges. My feeling on target loads is kind of meh, however. If I want to shoot mouse fart loads 38 SPL has 44 beat any day. As accurate and uses a lot less metal. The Skeeter +P level loads have some authority to them. I wouldn't hesitate to use them on deer (at near ranges) for example and certainly everything lighter.
As far as bullets go I have the following molds:
Arsenal's clone of 429421 custom ordered to throw .432 bullets. Weighs ~254 grains with COWWs+2% tin. Closer to 250-251 when cast of 20:1. Plain base.
(borrowed) Lyman 429215 two cavity in good shape. Gas check.
MP Mold's clone of 429244 hollopoint. Ordered to throw .434. Gas check. Casts ~240 grains in 20:1 with large HP, ~250 with penta, ~245 with small HP, and ~255 solid. This mold features a modern (Lyman devastator) type cavities. Not only do such conical designs work better with antimonial alloys, they work better with binary too. I was very happy that Miha went with these design rather than the old school design proper to the 429244.
MP Mold's clone of H&G 503 hollowpoint. Ordered to throw .432. Plain base. Casts ~250 grains with small HP pin in an alloy of 93-6-1 (pb-sn-sb). I've never bothered with the other pins in this one as I don't like them. Long, narrow, round bottomed hollowpoint cavities don't expand at low velocities and or at angles much off perpendicular (cavity implodes). I've also not bothered with the solids as the 429421 is so similar.
I have not done any HP testing in 44 yet. I am basing this off testing done in 357/28 SPL. So my hypotheses could be wrong, but probably not.
My sizer is .431 (my 624 has .432 throats) and all size properly, though the 429215 barely sizes at all. I have one Lubeamatic and it is filled with Carnuba blue.
The big surprise here is my decided preference for the Ray Thompson gas check designs over the Keith plain base. I wasn't expecting this. But it is true. In my case at least the gas checks shoot cleaner for sure and seem a bit more accurate and faster. I was also surprised that my least favorite is that 429421 as it was the only one designed for 44 special and not for 44 mag.
The 429215 in particular I like. It has proven to be quite accurate and pleasant to shoot vs the heavier designs. The friend I borrowed it from has proven it extensively on whitetails. At 1100 FPS he never failed to recover a bullet (complete pass through) and every deer succumbed within reasonable time/distance (none lost). Claims to have shot at least ten deer with it over the years, but lost track of particulars.
I was wondering if they are any other heavy 44 special followers out there (NOT INTERESTED IN REDUCED 44 MAGNUM LOADS--if you not using a 44 special case it is not a 44 special load) and what they have found.