I was worried about feeding but it's been great using the MDT BR mags. I'm a member at Gopher in Harris, 1k range and it's open to the public for Tuesday night shoots.
The opposite of a lightweight hunting rifle, but here is my 6 BRA (6mm BR Norma - Ackley Improved) Tikka. Built for PRS style competitions, 26" Bartlein MTU barrel, Athlon ETR, McRee G10 chassis. Shoots 105 Hybrids at 2920, basically zero recoil.
Looks great. I'm planning on basically the same build (though probably a 25" barrel). Do you know if it was a SAAMI spec chamber for the Peterson brass, or are you neck turning for a tighter chamber? I've got a bunch of Norma brass with 0.315" loaded necks and I've read that Peterson is similar...
Another powder similar to Varget is N140, velocities were almost identical in my 6 BRA. N140 hit pressure a little earlier but was more temperature stable.
The 6 BRA is the third cartridge I reload (284 Win, 6 BRA, and 6.5 Grendel). I don't hunt with it as the 6.5 does just fine on deer, and hoping one day to use the 284 on Elk.
As for ammo availability, sure it's impossible to find the first two on the shelf. But there is a benefit recently to...
The Tikka T3/T3x actions are all identical, won't have a problem there I think. The barrel profile would the the thing I'd look at, as long as they match for whatever area of the barrel channel was bedded (or the old barrel was larger profile) you should be fine.
I realize I'm the odd one out here hunting with an AR, but I love the ergonomics and adjustability of the platform. The 6.5 Grendel has performed great on whitetail and 129 LRAB's out to 200 (the farthest I am likely to have a shot where I hunt) but I've shot a PRS style match out to 600 with...
The XLR element for long action Tikkas can only use the MDT 3.56" magazines.
https://mdttac.com/us_en/mdt-metal-magazines-long-action.html
I'm not aware of bottom metals that can use those magazines, you're limited to the Element or MDT's long action Tikka chassis.
I have the Sordin Supreme Pro X (no LED) with the regular headband not neck strap. The gel pads are included and they're great, I bought aftermarket gel cups for my Howard Leights too. I've got a huge head and never had a problem with ball caps though now that I think about it I'm not sure any...
I'd think the poly/metal mags should work fine without grinding, it was my underanding that the thicker polymer feed lips were the problem. I've got some of the metal MDT BR mags that feed well in my Tikka. I'll be interested to hear how they work though.
As far as weight, the 5 rd Accurate...
Easiest route if you want the 6.5 PRC in a factory barrel would be either buy a 6.5 CM and trade bolts with someone (Tikka wtt mag/standard ads pop out once in a while) or buy a 270/300 WSM and buy a barrel.
I'm cheap so I'd lean towards X-Caliber or Preferred Barrel Blanks (but only the latter chambers 7 SAUM). I've heard good things about both, but more premium would be PVA who will also sell you a cut rifled prefit if you don't want button.
I'll pile on the recommendations for shorter action cartridges in Tikkas. They're perfect matches for 300 WSM, 7mm WSM/SAUM, or my plan for an elk hunting rifle is .284 Win. They're all great, accurate cartridges, and fit well with the long action bolt stop in the factory bottom metal and mags.