Below is my post with brief impressions of the Ruger American 223 AR mag rifle, in a thread discussing practical rifles. There's more discussion at that thread.
I am a skeptical type of shooter. I prefer my Mauser, M1917 and 1903 actions for their proven reliability and ease to maintain them. Even if a modern budget rifle can out-shoot my 1903 Sporter, I am willing to give up a bit of accuracy for the reliability of a military action. It's just what I prefer. I don't care if my Savage bolt action shoots more accurately than my 1903, I'd just trust the 1903 way more in field conditions.
That said, it does appear to me that the Remington 700 action has proven itself pretty well in tough field use, and is used hard in many competitions. Also, many competition rifles actions are essentially clones of the Remington. So I would therefore trust the basic action of the Remington. To use the inexpensive and available 223 cartridges, you really don't have a Mauser option anyway, so you are (with some exceptions from Ruger and CZ) limited to push feed sporter rifles.
You did not mention using detachable magazines, but now that I have a bolt action rifle that takes AR 223 mags, I really do like this setup. Easy and quick to load and unload. So with the Remington, to make my ideal rifle, you would have to add bottom metal (such as by CDI Precison) and then use fairly expensive AI magazines in 223. Personally, I think this would be a very good build: reliable, proven, and accurate. But it would probably cost at least $700 or more to put together. If you have the funds, to me it would be worth it.
But the Ruger Predator undercuts all of this by taking AR mags right from the start for under $450. Mine looked pretty good, and I think the action will prove to be rugged and reliable. Not M1917 trench warfare reliable, but still very reasonable. I still feel the action is clunky and needs some smoothing-out of the bolt as it is delivered, but I also think that this issue can be addressed and will then give you a reliable rifle. I describe the binding issue in the practical rifle post below. I prefer the feel of my Remington (action smoother by far, and no binding of the bolt under hard use), but for the cost, the Ruger brings what could prove a very good option.
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https://www.ar15.com/forums/Armory/What-do-you-all-think-of-the-concept-of-a-practical-rifle-Bolt-or-lever-/2-487282/?page=2
I just picked up the Ruger American Predator rifle, 223 AR mags. The predator has a 22" threaded barrel. I only had a chance to put a scope on it and sight it in at 50 yards. Using a front rest I was getting 1" groups with mil-surplus grade 55 grain ball ammo. I put about 40 rounds through it.
I like the rifle a lot. It is accurate and comfortable to shoot. To me, it will be a volume bolt action "fun" rifle, and takes the place of the military surplus rifles that I used to shoot lots of rounds through when both the rifles and surplus ammo was cheap and available.
The action on this could be smoother, and the bolt lift is still a bit heavy to easily work the action from the shoulder. There is some very small machined step or something in the receiver: if you cycle the action hard and push the bolt up and forward at the same time, it kind of catches a little bit and hangs the bolt up. The bolt is a bit stiff, and I am used to smacking around a Mosin Nagant action - which you never have to baby. I imagine that 15 seconds with a dremel polishing bit in the right spot would eliminate the issue, but for now I'll just concentrate more on pushing the bolt forward rather than up. The magazine worked well. It wobbles a bit since it does not have the deep mag well that an AR does, but did not give me any issues. Feeding, extraction and ejection were all 100%. After sighting it in at 50 yards, I shot clay pigeons off-hand in the backstop. It is a handy, reliable, and fun rifle. For the price you pay, you are getting a lot.
For me, it's just what I wanted. It would be an improvement if the bolt was smoother, but either more use, or some careful polishing, can take care of that.
It fits my definition of a practical rifle. It could use use some back-up irons to complete the "do-anything" package, and they could be added if so desired.
I tried the forward-mounted scout scope on both a Marlin 30-30, and with a no-gunsmith rear sight mount on a Mauser 98. That arrangement just did not work well for me on either of them. The scout scopes had low magnification but a fairly small eye relief area. Any speed for me was lost if your eye was not in-line with the optic.
On my 9mm ARs, I installed a traditional rear mounted scope, and that is faster for me. For the cost, size and weight, the Weaver V3 1-3x scope is great for close range work, with a little bit of magnification to help at moderate ranges. The Weaver is tiny and light, you hardly notice it's there. Really a great optic for light rifles used at modest ranges.
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ETA: I read up on the CZ 527, and it seems like a really nice action, a true "mini-mauser". It comes in 223, 7.62x39, and 300 BLK. Sounds like a contender to me. Proprietary magazines... but they look like well made steel, so no issue there.
CZ even sells a complete line of factory replacement parts. All the springs, firing pins, extractors... spares are all available. Even complete spare bolts. Sounding like a better option with everything I read about it.