21.5 gr of H110 in Starline cases lit by a Fed LP std primer. Bullet is an MP 44/444 305 HP. Gator checks and some home brew lube that I can't tell what it is.
Meet me at the range someday and you can shoot it. Velocity is 1325-1350 fps.
Glad to see you use the fed 150. Exact same load I use for 300 gr and up to 320 but I use 296.
I found a difference long ago between it and H110 where most guns like 296 while a RH loved H110. Hodgdon got a batch with a different burn rate then WW, same powder but it was sorted to each spec.
Now the S&W 29's. They can't take recoil from heavy boolits, internal parts geometry has too much inertia. They are OK with pressure and we figured 265 gr was top.
The big reason they never were in the winners circle is the grip angle. I had 5 or 6 over the years and I could shoot 1/2" groups at 50 meters but if I put the gun down, the next 1/2" group would be 10" from the first. Darn thing felt the same in my hand and I could center the first 5 chickens at IHMSA, put the gun down for target setters, pick it up and miss the next 5. I have trouble with the RH and a Bisley too. The SRH just needs held firm.
First thing that happens with recoil is the pin in the center of the cylinder that unlocks the cylinder will peen on the end so the gun gets hard to open.
Then the cylinder stop can drop and unlock the cylinder and hammer bounce can double strike a primer or out on the brass. Some cylinders turned back to the previously fired one so your next pull is a "click." If there is a live round there, the gun can double. The X frame in .500 was doing that. The stop spring was too weak and I believe S&W cured it.
They blamed it on shooter error with a double trigger pull. Tests we did with an empty, primed case in first under the hammer would fire when the next chamber went off. The cylinder turns backwards from rifling torque.
Hammer bounce is real on all revolvers and many rifles too. We have photos of hammers near full cock at ignition caused by internal pressure against the primer that kicks the firing pin and hammer back.
The S&W is a very easy gun to fix to stop the funny stuff.