A Bald Eagle shooting rest showed up. The Bald Eagle has some quirks that need to be fixed -- I'll post a thread on that when the time comes -- but for today I used it "as is," and it was definitely steadier and more comfortable with the TC than the other rests I've tried.
A rear bunny bag is in the works, but for today I had to improvise. The pic shows a couple of snowboot liners being employed as a rear rest.
Definitely not optimal.
Once again I tried the 200 gr. spitzer, but with some differences. This time it was sized 1-diameter at 0.359", instead of 0.3575" x 0.8 degree taper like last time. Last time I seated it out to engrave the rifling, but this time I seated it deeper so that it did not engrave -- I've never had much luck with engraved cast bullets in a TC, it seems to cause ignition problems, among other things.
As you can see from the notes in the photo, I walked up the powder charge until I reached what I felt was the max safe load, based on the chrono and on case head expansion.
Results at 100 yards for the 200 gr. spitzer with 15 gr. Lil Gun, CCI #500, 1.790" COL, heat treated wheel weight, Rooster HVR lube:
-- 1748 fps, 0.70% standard deviation for 15 shots (decent)
-- 2.1", 1.45", and 2.0" at 100 yards. 1.85" average.
-- a few of the cases were sticky to extract, suggesting that maybe I should back off the powder charge.
Next up, a 160 gr. plain base based on the Sensible Keith design. Since my 160 gr. PB revolver bullet shot surprisingly well last time, I attempted to "improve" it. I kept the same front band length, the same meplat, the same nose length, but stretched the length by using deeper grooves and a bigger GtoB. My thinking was that a longer bullet would be more accurate, all other things equal. The "improved" bullet also holds quite a bit more lube, but that was not the point since there was no sign of excessive fouling with the revolver bullet.
You can see that the "improved" bullet is slightly longer than the revolver bullet.
I walked up the powder charge until the velocity was the same as the revolver load, 2000 fps. Since the longer bullet seats a little deeper, less powder was required to reach the desired velocity. Results at 100 yards for 17.8 gr. WW296, 1.513" COL, heat treated wheel weight, Rooster HVR lube, sized 0.359":
-- 4", 6.3", and 3.2". Average 4.5".
-- 1982 fps, 0.56% standard deviation for 15 shots (that's pretty good).
Conclusions and Lessons Learned:
-- the TC definitely likes the 1-diameter spitzer better than the tapered spitzer.
-- the TC does not like my "improved" 160 gr. PB bullet.
-- I can't draw any conclusions about 0.359" vs. 0.3575" since there were too many variables today.
-- the Bald Eagle rest definitely helped me, but the lack of a firm rear rest was still a problem.
Things to Try Next Time:
-- reduce the Lil Gun powder charge on the spitzer load
-- possibly try WW296 on the spitzer load -- I suspect WW296 has a slight advantage in accuracy, and more consistent velocities.
-- possibly try 0.3595" or 0.360" on the spitzer load.
-- try the old revolver bullet at 0.359"
-- try different weights of plain base bullets.
I would be tickled if I could find a load that shoots 1 MOA in this barrel. And if I can find a respectable plain base load, I would like to use it to do some lube and design tests with it.
Obviously it would be easier to get bragging accuracy with lower velocity loads, but that's not my style.
I'm only interested in max loads.