Yep the 458 SOCOM would be a thumper but I have a Marlin 1895GS in 45-70 so I am trying to think if there is any real advantage to the 458 SOCOM in the AR platform.
I know that with a standard 30 round AR-15 clip it will hold 10 maybe 11 rounds of 458 SOCOM and the 40 round clip will hold 14-15 rounds and have read that with some of those high round count round mags you can hold 40-45 rounds. which in the end would make it a heavy dude lol. Plus with the recoil of the 458 SOCOM you are not going to have what people would call fast follow up shots lol.
The Marlin Holds 5 rounds but it is lighter I think and very handy and not all that hard to throw rounds into the mag tube. Plus if walking around someplace people will not really give a Lever gun a second look but an AR Platform they will give a hard look and not a good one in general.
I think where the AR platform and the 458 SOCOM would really shine would be with a short 14" or 16" barrel in Dangerous BEAR country and close range you could throw some lead pretty fast if needed.
Come to think of it I am surprised that all of the Police and Game Officials up in Alaska do not carry the 458 SOCOM in the AR platform. As all they would have to do is have two uppers one in .223 and the other a 458 SOCOM if they felt the need. Instead of a 12 Gauge Slug gun.
And I forgot to mention have you priced 458 SOCOM ammo lol. $80.00 per box of 20. Thank goodness Starline has brass and they are easy to load for with easy to get bullets. . I pucker just thinking of $4.00 per round lol.
I just now checked lol. At Starline the 458 SOCOM Brass runs 250 for $204.00 and 500 for $340.50 about Double the cost of 45-70 brass.
So Yes I think I talked myself out of the 458 SOCOM as you do not get the same bang for the buck as 45-70 plus there is no big advantage for the 458 SOCOM unless you have a need for something compact that can carry double or triple the rounds of a Marlin 1895 Guide Gun.
But then again if you hit anything with a 300 to 500 Gr bullet going between 1500 FPS and 2300 FPS and it smiles at you then you know you have some real problems ahead lol. And you might have thoughts that maybe you should not have put that scope on that rifle as it will really hurt when that brute puts it up your Keister lol.
But I still feel the .358 Winchester in an AR type Platform would be the Bees Knees. Too bad at least for myself it is cost prohibitive.
Speaking of the .358 Winchester here is a good read. http://www.leverguns.com/articles/paco/358_wcf.htm