I was all set on building a 20 Tactical on a XP-100 action until I seen a friends 20BR shooting berger bullets at 4300fps with tiny groups.
Pros and cons please! I realize the 20BR brass is a bit more tedious to form but still like the idea!

I answered this post on the Reloading forum, as well, but here's a couple more items. If you go with the 20BR, get your chamber set up for using 6BR Lapua brass as the parent case, not 6BR Remington. The Lapua brass is absolutely beautiful, but it is a tad larger diameter at the base than the Remington. 6BR Rem brass comes primed. I imagine it's their 6 1/2 primer, but not sure. Lapua brass is unprimed and with drilled flash holes. I formed 400 cases at one sitting. After using an ironing die, no neck turning was needed, but there was a lot of trimming to do. Having a Wilson Trimmer with a powered accessory driving it makes for short work of it. I used the Ray Smith 20BR reamer, which has a 35 degree shoulder.

My 20BR is on a rifle platform, with a 24" #7 Shilen. It also wears a muzzle brake. The brake is to further reduce muzzle lift so I don't lose the target in the scope and I can call my own misses very easily. There really isn't any recoil, especially with the heavy barrel. It's a nice cartridge.

Sam,

Thanks for your thoughtful opinions and advice.
I will definitely go with Lapua brass if the project goes forward. I am not familiar with an ironing die, could you please explain use and a source?

Thank You,

Roger Queen