I tried working up a 250 grain Keith-Leadhead, sized at .430" in a brand new 4" 629-6, the bullet does not drop through the cylinder, nor does a .429" and I've read that the new guns have tight cylinder throats.
I started at 21.5 grains of H-110 and got 1223 fps, case extraction was slightly sticky, I then went to 22.0 grains for 1237 fps and case extraction was stickier, I quit there.
I called Hogdon and they suggested backing the load off to 21.0 grains rather then going forward to 22.5 grains. I mention this because of Hogdon's warnings not to REDUCE charges, I though this might be giving me the pressure signs?
I haven't had a chance to try the reduced load yet.
I can run this bullet at 1207-1245 fps with 20.5 to 21.0 grains of 2400 without case stickiness, so I'm not real sure whats up yet. The 21.0 grain load is hot for me and this gun and I've received good results with the 20.5 gr. load so I'll probably stick with it for awhile.
What I plan on doing is using 2400 and AA9 for the time being, since I can reduce those powders down and work up. Velocities are good and I'm not getting pressure signs.
I've read over and over again that the cylinder throats are tight in the newer Smiths and I "think" this might have something to do with getting early pressure signs. And the nature of 296/H110 being what it is, I've chosen to work with other powders until I decide whether or not I want to open the cylinder throats up.
On a different but related note, I have achieved 1130 fps with 20.0 grains of H110 and a 280 gr. BTB WFNGC sized to .429", this load has so far been accurate with easy extraction with my limited testing. Surprizingly 19.5 grains at 1109 fps DID give slightly sticky extraction???
Hogdon told me to use their Jacketed data for this 280 gr. bullet, 18.5-20.5 grains.
New Starline brass and CCI-300's with 2400 and AA9 and CCI-350's with H110. Moderate to heavy crimp.
I've run about 300 mild 240 grain LSWC and 200 "warmish" hardcast loads through my gun without leading issues.
As usual, please do your own due diligence when it comes to reloading, I typed this quickly and on the fly, and probably made mistakes, so please double and triple check any load data with published data, what works in my gun may be dangerous in yours.