I've been reading the thread on the Ruger GS with considerable interest.
It is indeed interesting to see each new generation's view on the all-around rifle. My experience suggests a .30 caliber with barrel length not less than 20 inches.
Any scoped rifle MUST have ruggged backup iron sights with a reliable 200-yard zero.
I was influenced by WWII vets who spent their post-war outdoor work in Africa, Alaska and Asia. These guys all felt that an accurate, reliable bolt rifle which presents a low profile and "does not scare the natives" was the right way to go. A lone man in the bush with an assault rifle attracts unwanted attention. If a lone man is confronted with multiple adversaries, the role of his rifle is to "create a window" for escape. Buy time, seek protective cover and maintain concealment during a rapid distance creating movement to execute escape and evasion. Quite literally to "shoot and scoot." In the words of my mentor, the late, retired clandestine services officer Harry Archer, "if you stand and fight you'll never live to shoot them all..." Lt. Hiro Inoda of the Imperial Japanese Army, who held out as an evader on the island of Lubang, Phillipine Islands, until 1974, lived it. His book "No Surrender, My Thirty Year War" was required reading for SERE students in my day. May still be.
Like Evan, I gave up on a semi .308 because any which were light enough did not delivery the accuracy or reliability needed. I have used .30-'06 bolt hunting rifles for 30+ years, and have formed some opinions, which are to be expected for 60+ year old, carmudgeon.
I have used various US semi-sporters, Remington 740, 741, 742, Winchester 100, Browning, Valmet and HK. Only the HK grouped under 1-1/2 moa with factory hunting ammunition, as good as an accurized Garand, but its fluted chamber and delayed blowback roller locking are VERY hard on brass, a non-starter for me.
My most carried and used boltgun is a pre-WWII (1936) Winchester Model 54 in ".30 Gov't '06." The 54 was heavily based on the Springfield, pre-dating the Model 70. It is clip slotted and intended to be rapidly reloaded using Springfield stripper clips. Its open iron sights are fixed, Euro-style having a solid, flat-topped standing bar with deep U notch, and 1/16" bead front . These are VERY rugged, give a clear sight picture and came perfectly zeroed for 220-gr. ammunition at 100 yards, 180-gr. ammunition at 200 yards or 150-gr. ammunition at 300 yards. A second folding leaf came blank, intended for filing-in by the user. Mine hits in the center of the bead at 400 yards with 150-gr. ammuniition, or at 100 yards with a reduced small game, turkey or coup de gras handload using a 150-gr. flatpoint .30-30 bullet at about 1400 fps with 16 grs. of #2400. I also have a Lyman 48 receiver sight which fits this rifle and while works well, it is more fragile, so I very seldom use it.
I never felt a need to scope the Winchester 54 because it is a trim woods-walking, snap-shooting gun adequate for "short range" (in the infantry sense) to 200 yards on deer sized game. I seldom have needed to shoot farther. I can efffectively engage Army D targets to 400 yards with the open sights if needed. Hanging alot of extra optical equipment on the rifle defeats its handy purpose. Its original factory stock is trim, European style with comb and pistol grip ideally proportioned for fast timber iron-sight snap shooting. The pre-WWII sporter stock makes a pre-1964 Winchester Model 70 feel like a fence post by comparison. The rifle weighs 7-1/4 pounds, is a thoroughly reliable 1-1/2 minute grouper, has rock-hard sight dope at 200 yards, ridden thousands of in a saddle scabbard, and killed literal truckloads of game. If Jean Luke Piccard of the starship Enterprize would beam me down onto my own virgin planet rich with big game, it would still be my choice.
My "other boltgun" is a Mauser by Ernst Appel of Wurzburg, Germany, which dates from the early 1980s. It is typical of those built for GIs who had too much re-enlistment bonus money in their pockets in the Cold War era, it is also stocked in European style, with fixed, very rugged iron sights zeroed at 200 yards. It has quick-detachable EAW scope mounts with Zeiss Diatal C 4x32mm scope and German No.3 reticle, far superior to a crosshair in evening nautical twilight. It is also a reliable 1-1/2 moa grouper with 180-gr.. RWS TUG or Federal 180-gr. Premium Noslers, and has killed lots of game all over the world, US, Africa, Europe, Asia.
My "modern" boltgun is a "switch-barrel" which these days serves mostly as a test platform and admittedly is mostly a "range queen" in my retirement. Barrrels can be readily changed between 7.62x39, .308 Win. or .30-'06. It is built on a Sako action, bedded in a McMillan USMC M40 pattern stock, and barrels are of a contour similar to the '03 Springfield, free floated, with M14 front sight, so I can either use the Sako peep sight (again with 200 yard zero) or quick detachable scope. Each barrel has its own pre-zeroed scope in its own mounts, a Millet DMS 1-4X-30mm for the 7.62x39, and Zeiss 6x42mm Diatal-Cs for the .308 and '06. The rifle weighs 8 pounds with scope and all barrrels are comfortably sub-moa with good handloads in any calibers for which it is suitable.
The 7.62x39 barrel is used for gong practice, to exploit inexpensive surplus ammo. The .30-'06 is the bean-field, deer hunting caliber of choice. Having the .308 barrel also available is to exploit local ammo stocks, in an effective alternate deer caliber.
These are hunting rifles not "tactical." I have fired all on a modified Infantry Trophy course out to 600 yards and confidengtly know that repeat strings of rapid fire, up to 20 rounds within 5 minutes, do not appreciably open groups or cause point of impact to "walk." My normal zero check is to always fire the first shot out of a clean, cold barrel onto a laminated sighter target which I save, make and date for trend analysis. The next four shots are fired within about a minute on a separate record target. I remove the bolt and insert a steel cleaning rod into the bore as a heat sink while I walk down to the pits to pull, mark and re-face targets. I then repeat 5 shots, slow fire on a clean target, firing them in about 3 minutes, from a fouled bore which has been allowed to cool to ambient temperature. By the time you have repeated this 200 yard exercise a dozen times, in all seasons and types of weather, there are no surprises. A stable rifle with rock-solid zero inspires confidence.