I used to do neck turning/truing. I both did inside and outside turning. I eventually gave it up as unnecessary once I stopped shooting pistol silhouette.
I could recommend a good 3d printed cutoff jig.Yeah, I ordered brass for expedience but will make my own from "approved" brass going forward. As a worst case, I'll just toss these "unapproved" cases into my brass recycling bin. I tend to find a lot of .223 brass at the local range, and can order it from SNS casting for $0.05/round with 95% being lake city.
Just need a harbor freight cutoff saw
Therein lies the rub. I think I've found a way around the whole thing - just resize my bullets to .308 instead of .309. the SAAMI specs tell us that the neck of a 300 Blackout cartridge loaded needs to be 0.334 diameter. with a neck wall thickness of 0.013 and a bullet of .308, it comes out to just right (0.308+0.013+0.013). The Lakecity and FC brass has a neck (once a case wall) thickness of 0.011 on average, and brands like Wolf and PPU have a wall thickness of 0.013-0.015 which puts it a bit out of spec. As long as I'm shooting powder or hi-tek coated lead bullets, they remain malleable enough to chamber, but jacketed bullets using the wrong headstamp...not so much.I recently reformed some .243 cases to .22-250 cases. I had to turn the necks, but that was because after reforming, trimming and annealing the new necks were the old shoulder material. The shoulder brass being thicker I had to turn off about 3 to 4 thousandths. You shouldn't need to turn yours though since you are shortening the cases and expanding the necks. Neck thickness should be about .013.