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Today was the last of my days off, so I followed through with my other plan and somewhat, the suggestion of Artful. This time, I used a flux and brushed the inside of the otherwise new RP cases. I had any a small amount of tin so I mixed 1000 grains of tin with 3000 grains of lead and fluxed the mixture. Then to get as close as possible to exact amounts, I made a blank mold that resembled a thick wire (just drilled with a 1/8 drill to make the mold) and cut each flush with the top of the mold. I then weighed out 220 grains again, trimming as necessary, which this time was more volume and repeated the melting process the same as before.
Same as before, the lead/tin mix separated from the case in 6/10 of the shots but group size was still good at approximately 1/2". I still do not have the chrono to measure velocities but I'm teetering back and forth as some are obviously going supersonic while others are not, I'm not sure about how consistent the velocities are but they must not have a terrible spread as I see no noticeable vertical stringing.
Also a second experiment:
I've had pretty good luck using "Power Pistol" powder in other subsonics, I thought I'd give it a try with the 308.
Again, I have almost no reference to begin with so I started at what I thought would be a mid-level charge of 8.0 grains, otherwise, same load as above, 168 SMK, RP Brass, Fed 210 Primer, 2.800 OAL. This charge fills very little of the case so I suspected that it would be very sensitive to positional changes. I opted to fill the case with 3.5 grains of loosely-packed cotton ball material. My initial thought was that this may burn with the powder and not exit the barrel. Again, I loaded only one loading with the idea of further testing if the prelim looked even hopeful.
At the range:
EXCELLENT accuracy out of the Rem 700 20" BBL Tactical 1/10 twist barrel. The group, including a cold bore shot was one ragged hole, probably in the neighborhood of ¼” CTC. I did not have comparison between subsonic and supersonic and this powder sounds much different that the H110 so I'm not sure which side of the line I was on. My guess is that this was slightly over subsonic as a comparable load in my whisper would be/has been supersonic with a 200 SMK down to 7.0 grains where it averages in the 1070 FPS range. The 308 Obviously has a larger case capacity but I think this powder burns fast enough that everything is mostly stable by the time it exits the barrel, I don't know, I could be wrong.
Although this was good news in the accuracy department, it was a no-go for the suppressor crowd, or at least those that can't be disassembled for occasional cleaning. The cotton ball does not burn up in the barrel and exits the muzzle as a fine spray that appears similar to floating cob-web, not really an excessive volume, but it’s there all the same. There really isn't much more visual effect than a little bit of smoke, but it is obvious that it isn't completely burning up. Maybe gun cotton or the puff-stuff that were talked about earlier in this thread could be substituted with better results. On the plus-side, Power Pistol burns very clean if you get at least an average crimp on the case, there was no noticeable residue in the barrel and the insides of the fired cases were still very clean. No signs of excessive pressure or indications of any other problems. Maybe next week I'll try a run without the filler to see how position changes velocities. I should have my chrono repair parts in by then. Anyone else who tries any of this, or variations, post up... I've now got another itch that needs to be scratched (I knew I shouldn't have read this thread when I saw it!).
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