Magnum primers and nitrocellulose update
I think I may have made a batch of magnum SPP's today.
I was making a second batch of EPH25 and using the 100 mesh NC from my coffee grinder. It's wonderful not to have to grind with the mortar & pestle for a half hour or so just to make 100 primers. Anyway, I had a batch of EPH25 already made up, sitting in a small container ready to divide into the cups. I dropped 100 cups into my primer loading plate and sprinkled the mixture over the top as I had before. To my consternation the mixture did not fill all the cups. During previous sessions, I'd have to scrape and spread the mixture many times to help convince it to fill up the cups. This time, I spread it all over, and there was plenty of room left. Several cups were nearly empty, and others at various stages of filling. At first, I figured some of the cups must be overfilled, so I gently teased the powder out and kicked it around, but it was obvious that the cups were still low.
I did some quick math and made up a quarter batch, stirred it up and spread it around. This time it really did fill the cups up. Unsurprisingly, when tamping, it seemed to me that the cups were now somewhat more full of mixture than in the past. I finished wetting, placing the paper wad, anvil and set them. A bunch of anvils were hard to set and kept wanting to come out. I decided then to prime the cases while the mixture was wet, anticipating some AD's if I waited for it to dry. Seating the primers I noticed that many did not want to seat the last couple thou or so and needed some real encouragement to get to the happy flush/slightly below flush seating point.
The only difference between this batch and the previous ones, was that I ground the entire EPH25 mixture in my mortar & pestle after mixing. Normally, I just mixed the Lead Nitrate, Lead Hypo, Pyrex and NC together with a glass rod for a few seconds, then spread it over the cups. I think the LN got ground up very finely this time. The LN comes out of the bottle like fine play sand, and previously gave a very gritty feel to the mixture. This time, it was like spreading talcum powder. I'll have some more experimentation to do here. I also noticed that the wetting process was more like EPH 20 this time instead of my previous batch of EPH 25 where the mix seemed to slightly resist wetting.
I'm considering doing a test like one on Rumble where different mixtures are fired in empty cases in a dark room with a pistol and a ruler to show relative flash levels. I'm really wondering how these primers stack up with flash level compared to commercial primers.
I am trying a new case drying technique since the cases are wet primed. I put a 1" thick spacer grating on the bottom of my Instant Pot, put a circle of cardboard on top, and placed my primed cases on top of that, sitting in their ammo trays. Now, if somehow I had a detonation during drying, the blast would not affect any of the adjacent primers. I have it set to 130 degrees for 12 hours. I do not anticipate any issues with having cardboard in the Instant Pot, I can already hear folks recommending against that due to flammability concerns. I'll probably use something else eventually, but I wanted a buffer to keep the primers off the bottom of the pot where the surface temperature is higher.
NITROCELLULOSE
In order to speed up the process of making future batches, I wanted to make a bunch of 100 mesh NC. I threw about a quarter cupful of Power Pistol in the coffee grinder yesterday. Every so often, I'd grind it for 60 seconds then move on with my day and let the bearings cool down. I did this perhaps 5-8 times between yesterday and today. This evening, I finally dumped it all onto my 100mesh screen and sifted. I got about 90 more grains of fine Nitrocellulose. Added to what I had before, I now have enough to make about 2,400 primers. This step eliminates the biggest PITA of making a batch of primers. The NC really resists grinding, but using a larger volume helps it grind much more effectively. For anyone already making primers or thinking of getting into it, a cheap coffee grinder dedicated for chemicals is proving to be extremely valuable. If I want to make more ground Pyrex, you can bet I'll be recruiting this little guy.