Ok If I said I going to build a dedicated 600 yard gun to shoot at CMP, what barrel types calibers would you use? Not worried about optics or weight or specific products. Just off the top of my head I'd say a 20 in. heavy or at least "heavier" barrel. 5.56/.223 wylde over 300bo/6.5 grendel combination? Free float and non compensated. Any opinions? Anything else important I might be missing?

I’ve got a 20” and a 24” white oak barrel that is deadly accurate. I’ve shot to 675 with the 20”. Haven’t shot the 24”

I'd do a 20" Bull. 600 yards is no problem with .223 and ammo is readily available and going to be cheaper to shoot than your other options.

If I were to just buy something would be hard to beat a Ruger Precision. Just buy it and start shooting..... it IS that easy.

20", 223 Wylde, bull non threaded.

I've got a 18" rifle gas 1/7 wylde that loves my 77gr smk(no cannalure/2650 fps avg) that will play at 600 all day long. Haven't tried at 800 or 1000 yet but this summer it's play/test time. Told myself if I'm going longer than 18 I'll just build a 224 valky

Are you planning to shoot matches or are you just piddling?

If you go the .556/.223 Wylde route, order the White Oak Service Rifle barrel and be done with it.

https://www.whiteoakarmament.com/sh...ustom-post-ban-service-rifle-barrel.html

Add a float tube with a match trigger and you are GTG.

If you plan to shoot sitting or prone and sling up, you'll need to order the White Oak Service Rifle Railed Gas Block, .750"

https://www.whiteoakarmament.com/picatinny-750-clamp-on-gas-block-for-service-rifle.html

It has the cut out for the front sling swivel on the float tube.

You'll need to stick with the 75, 77 or 80 gn. projectiles.

Accuracy with the White Oak barrel will generally start to fall off around 2500 rounds.

Is the fall off in accuracy an issue in .224 barrels too? I was thinking that was more an issue in the 6/6.65 barrels. I'll start out piddlin but matches aren't out of the question either.

That is what I have in mind right now.

I work with a guy that is in the process of building a .224 Valkyrie. He's going with a 24" Shilen barrel, no idea what lower he has in mind for it. He's hoping to have it built and shoot it sometime within the next month...I'll let you know what he says about it.
In the meantime, there's this...This guy started with 3 different bullet weights, a 28" barrel, a chrony, and a cut-off grinder. Interesting article, with some interesting results...

http://bulletin.accurateshooter.com...el-cut-down-test-with-60-75-90-grainers/

Valkyrie seems like a new twist on something that's already out there that needs less modification--223AI. Thoughts?

I've been shooting the Valkyrie a little. I'm not really sure what I think about it with respect to comparing it to a variety of other cartridges. It does perform well with the heavier bullets making it a pretty nice low recoil package for long range shooting. Otherwise I'm not really sure about it for a hunting rifle, long range coyote rifle, etc. I'm just not sold on it for anything in particular. I'm kind of tired of the AR cartridges really. Great for AR platforms but when you swap to a bolt gun that all changes.

My only gripe with something like this for long range is you can't see the splash or see the holes in the paper. That gets old quickly.

You can at CMP Goatkiller. Shows you on the monitor where you hit. Got my lower in today.Going to start on it and go from there. Think I know what trigger and butt stock I'm going with. Looking around today parts are getting scarce. Good thing I'm not in a hurry.

For you my pick would be the Ruger Precision in .223. That's pull it out of the box take it down there and start punching holes kinda easy.

If you want to build a rifle... obviously most of us on this board get that too. You can probably get an AR platform to shoot well at 600. I know you can if the goal is for entertainment/fun.... but if you intend on shooting matches in the future you'll probably be back to a bolt gun. So just consider that. All AR platform matches are fun though. You'll be at no loss either way.

I just built the same thing kinda. I wanted a fun gun that I could stretch out a little. Ended up going with a Criterion 18" HBAR in 223 Wylde. 1-8" with threads. Looking back on it I wish I would have gone 20" with a target crown. Put a cheap Jerry Miculek style compensator on it, and with earplugs and muffs shooting under the pavilion, it will rattle fillings. Have yet to put a scope on it yet, but was planning on an SFWA fixed 16x but thinking now about going with the vortex strike eagle to give me a little more flexibility.

I went to 6.5 Grendel to dabble in longer range AR shooting. I've shot my 223 wyldd 16" out to 500 easy enough but I wanted something that would actually be useful at that range. I put together an upper with a 22" Satern barrel. It will shoot .3ish moa if I do my part with factory Hornady. I'm going to try and stretch it out to 800 or so when I can find someplace to do so.

Got my lower in and thought I would throw this out as a PSA. White Oak Armament will let you "build your own" LPK. I really just wanted springs an roll pins and wasn't aware they did this. It might come in handy for somebody.