Steve, Several years ago, I built myself a 20 Vartarg on a Rem M700 CDL SS that I purchased new as a 17Fireball, just to get the action & stock. I pulled the fluted stainless bbl and sent it to Bartlein with the request to duplicate the contour on a 20 cal, 1-11 tw blank, which they did. It made a really fun rifle to shoot, but there were no decent dog towns out here to use it in, and so I eventually sold it to a fellow who was planning a PD safari up in the Dakotas. The one-and-only drawback at the time was the poor quality of a 500ct box of R-P 221FB brass I bought for it - almost 15% of those cases had shallow primer pockets. They were so shallow that I couldn't seat primers flush in them. A few years later, Lapua started making 221FB brass, but my reamer cut a .232" dia neck, which would've required neck turning (this was after I'd sold my Vartarg), and probably due to limited demand, they ceased production. So where does that leave us where a source of quality 20VT brass is concerned? The only thing I've seen is brass formed from military 5.56 brass, which is probably just fine, but it's not always available, and since I've never bought any of it, I have no idea how thick the necks are. I'm currently enjoying a couple of rifles chambered for the 20 Tactical (Howa Mini in a Boyds ProVarmint w/adj cheekpiece and a trued M700 in a McMillan Game Scout, both with Bartlein 1-9tw bbls that shoot well with Berger 55LRBTs). But honestly, I'd love to build myself another 20VT on a Howa Mini action, and would probably do so if Lapua would re-start 221FB brass production...
I've read about those problems with the RP brass but your batch must be particularly bad. My older batch is normal and has also lasted for 5-6 cycles.
And darn-it, I didn't know Lapua had discontinued their nice brass.
That leaves Norma 221FB brass which is supposed to be good brass and pretty much interchangeable with Rem brass from what I've read. It's what I'll buy next.
Then of course forming from military 223 brass which would be a PITA. There was a guy named Abe Bently that sold formed brass over on Saubier but I doubt he does it anymore.
The reamer came with my rifle so that makes it so I have to turn the necks but I haven't done a new batch yet because I got 300 brass with turned necks with my gun.
A recent problem is I can't find H4198?? This powder fills the case right to the bottom of the bullet and isn't temp sensitive. I might have to switch powders unfortunately. 18.8gr is what I use for 3750 fps and 5.5grs of 800x for the reduced load. I'd use trail boss for reduced loads but its annoying getting the powder into the small neck.
Because I lose 300 fps using 40 grainers I'd stick with the lighter bullets vs the 55gr. Wanting to reach out far with more energy is where your 20T would come in handy with the heavy's.
Though I tried a few more fun chamberings the last decade like 20x47L and 223AI (both fast twist and the heavy bullets that would blow up mid air) I abandoned them. I've slimmed down my choices of long guns to 5mmFBI, 223 with 70's, 6mmBR with 107's, and 6.5Saum with 150's seated out far in a long action. I can't chamber my own so I need good barrel life.
But the 5mmFBI gets shot the most because its such a joy! I really like using the reduced load out to 300Y on our little animal shaped steels, especially in a good breeze. It's a killer load for plinking but providing challenge in the wind and at the same time without dealing with the lousy vertical of the rimfires. I can shoot many rounds basically until I'm tired of doing so and the barrel doesn't get HOT. Easy to self spot with due to low recoil, cheap to shoot, long barrel life, long brass life, much to love!
With my 22mag the vertical is pretty bad at 300Y and blows a lot in the wind, same with mid quality 22lr ammo. I get decent vertical with expensive 22rf at 300Y but its $18 a box of 50 now so very seldom do I use it for plinking, instead I save it for matches.
If this 20VT case were shortened a tenth of an inch I think it'd keep that 3750 fps with a 2" longer barrel and AA2200 powder, while fitting into a sweet tidy little action, hint hint - Mike, smile.
I've reloaded 5.7x28 and it's a PITA because the case is so thin and short, also its very sensitive to even 2/10's of a grain difference in powder, and that's not all the problems I encountered.
The 17K hornet was kinda cool but it lacks energy and its hard to spot misses because the bullets are so light. It's an overachiever for what it is but......
It can be really hard to see misses at my friends place with his 17hmr. Ha, on a windy day at 300Y I outshot him with my pcp air rifle which uses 42gr slugs because he couldn't see where he was missing but I could see where I was missing.
It's the multitude of these subtle little things that make the 20VT case size such a great choice.