Most of the TDF series has been about preparing people for more gun-restrictive times coming, and thus going DOWN from what is now generally available. However, as I have occasionally posted "caveats" to the image of effective lower-end arms, here I will address the matter in a more affirmative manner--that is, building one's armory UP in class to an effective level. Specifically, I will address the private "fighting rifle."
The term, "fighting rifle" has been around in the 2A/RKBA community for some time. It's basically a generic way of getting around politically-pejorative terms like "assault" or more narrow terms like "battle" as adjectives for one's primary long gun. (See HERE for a discussion of long gun versus sidearm. As a caveat to it, remember that which of the two is "primary" is dependent on the situation.) Civilians don't "assault" things legitimately on their individual discretion, and yet they envision themselves doing run-and-gun like in those "A-Team" reruns they watched just a few too many times. "Battle" points to a function more formal than they have in mind, plus having a specific meaning in the arms realm not so fitting with their "A-Team" image. For 2A hobbyists driven by nothing but personal indulgence that could be satisfied by inert models, "fighting rifle" distinguishes a weapon they might actually use from the toys they play with to poke the ATF'nE or eek out the most tacti-cool-ness they can in restrictive jurisdictions.
In this vein, and in the theme of TDF, the question arises, "What SHOULD private citizens seek--what do they NEED--for the function of the Second Amendment as a 'fighting rifle,' and in consideration of technological and social--and frankly political--factors?" This means what works AND what is feasible to rely upon holding in this post-Election Steal America.
First, the core condition here for our private setting: FORGET FULL-AUTO. Again, forget full-auto. The technical definition of an "assault RIFLE," regardless of colloquial or legal usages of the "assault" term, includes selective-fire capability. For our purposes here, that aspect will be carved out as much as feasible. (See TDF 10 on this.) Obviously, though, SEMI-automatic, as opposed to manual-action, is the intended and preferable operating system--though political realities exist (see TDF 2 and TDF 73).
Next--and with the above in mind--there is a real tactical, though not usually legal, distinction between an "assault rifle" and a "battle rifle." The two articles below provide usable definitions and distinctions:
What are the differences between a Battle Rifle and an Assault Rifle? - Beginner Gunner
Firearms Semantics: "Battle Rifle" and "Assault Rifle" -The Firearm BlogThe upshot is that a "battle rifle" is a heavier arm with a heavier caliber more akin to what was common prior to the AK47 being actively and openly deployed in the mid-1950s--M1s, M14s, FALs, G3s, MAS 49 series, SAFN49s, and the like. For the Western world, that generally means 7.62mm NATO and some older calibers (.30-06, .303, etc.). Their focus on per-round power, even in maneuver warfare.
An "assault rifle" (non-selective-fire for our our purposes--per the above core condition) is a lighter arm with a lighter (intermediate) caliber akin to military rifles adopted since the 1960s--M16s (AR15 as civilian analog), AKs, G36s, F2000s, etc. For the Western world, that means almost exclusively 5.56mm NATO, usually with AR STANAG magazines. Their focus is on the run-and-gun maneuvers people saw in those "A-Team" reruns. EDITORIAL COMMENT: I.e., those things civilians are generally neither trained nor disciplined to do. More on that later.
It is the position of TDF and yours truly that the 2A civilian Militia would best be served, and be most effective, to have a more "battle(ish)" long arm than the current crop of ARs and other 5.56mm weapons (see TDF 19):
Caliber is a major issue here. On the one hand, there is the recognition of the overwhelming predominance of 5.56mm/.223 ammunition in both private and public stockpiles versus 7.62mm. Interoperability is always a high consideration. On the other hand, there are already inklings of specific restrictions on that caliber, at least in PC-private sales. The solution to how much we ought to play to the current supply situation versus how much we should anticipate future legal and tactical changes is a matter of judgment.
So, the answer to the question about a civilian's "fighting rifle": A military-grade/"sturdy" or "rugged" rifle in 5.56mm or 7.62mm NATO, much preferably semi-auto. Most of the "evil" features associated with "assault weapons" bans are simply of low importance tactically to untrained civilians. (We are talking tactically, not constitutionally.) Legitimate private defense with full-power rifles are almost always set-position, which goes to the TDF argument on 7.62mm. And yes, even bolt-actions (and other manual-actions, for that matter, including some pump and lever AR and AK variants) can lowly function as such (TDF 100, see also TDF 36). That said, the more "sporting"--PC-looking--the less effective. Such are fundamentally not "fighting rifles." (But then, see TDF 30 for a little art-imitating-life mitigation on that.) A very few alternate calibers like .30-06 and (in Canada) .303 can play a legacy role, but are far from ideal.
As for specific models, the entire TDF series has presented a number of "featureless" options, both semi-auto and manual. The key points are caliber and durability. I will point the reader to TDF 57 for some California ban-beaters, though the bullpup would be a very bad choice, as that configuration is already banned for import. Anticipate what will happen tomorrow.
FIGHTLITE SCR in 5.56mm (discussed in video at TDF 57). Not an endorsement, as I have never seriously handled this model weapon:
One specific characteristic to be mentioned involves detachable magazines for 5.56mm. The AR STANAG (NATO Standardization Agreement) magazine is as ubiquitous a magazine as there is in the North American civilian realm, even beyond the M1911 .45 magazine. Interoperability with them is more important than the specific model. It is unfortunate that Ruger with their Mini-14 and various manufacturers of 5.56mm AK variants commonly have different, often proprietary, magazines for their arms, and conversion to AR mags on some *cough Ruger* is near to impossible. Remember: AR mags if using a weapon with detachables.
With 7.62mm, there is far less commonality, which is likewise unfortunate.
And of course, this would not be "The Daily Fudd" without mentioning a few manual-action arms: Mossberg MVP "Patrol" and Ruger American "Range" in 5.56mm, which take AR magazines, and refurbished or even somewhat sporterized Enfields originally manufactured in 7.62mm (TDF 100). For a more modern approach--and one in actual semi-military general issue today, the Canadian Rangers' C19--a take-off on the Finnish Sako T3 "Compact Tactical Rifle" (no longer manufactured, I'm given to believe)--offers potential (TDF 12).
Ideally, both a semi-auto and a manual-action in both 5.56mm and 7.62mm should be kept, to anticipate both tactical and potential legal developments. But cost and other factors can make that difficult in some cases.
The upshot of this is to keep (per 2A) something you reasonably can, and which will serve the basic function of a CIVILIAN "fighting rifle" as shown above--and to keep it simple! Don't let your hobbies or resentment of ATFn'E be your guide (see TDF 66), and keep preference (there is no standard official "Militia Rifle"--yet; see TDF 19) in check by reality and Militia efficacy. Limit your "features" to those you are indeed qualified to employ effectively (see a discussion HERE about such upgrades, but note some are features clearly in the sights of the anti-gun forces in control in Washington), and be ready to part with them should legal exigencies arise. In many cases, the resources used on them could better be spent on practice, political activism, and another 10-round magazine or five. "Featureless" really is sufficient generally (TDF 53 and TDF 54), and at this point should be considered with regard to new purchases (such as might be available). Planning for rendering presently-possessed arms you aim to keep compliant is advisable, even if you might be willing to pay the $200 tax. (As for "burying" them, it's the same as surrendering them--they are effectively unusable in an urgent situation; see TDF 95.)
"Fighting" isn't about preference. It isn't about "rights" or "liberties," or even, "Da Constitution!" It's about effectively throwing kinetic force against an enemy. FIREPOWER is the prime commodity, and retaining FIREPOWER is more important than the features. It's worth the sacrifice.
TDF INDEX: Cats, Guns, and National Security: THE DAILY FUDD index. https://catsgunsandnationalsecurity.blogspot.com/2021/03/the-daily-fudd-index.html