I have 3 GI M1 Carbines, and I have owned half-a-dozen others over the years. Within the original parameters of design and performance the M1 Carbine is a fine piece. However, the M1 Carbine was never intended to be a precision shooting instrument. Very few will deliver even 3 minutes of angle, and most will be closer to 6 MOA at 100 yards. The cartridge itself is not a high performing choice for any application, being most similar to the older .32-20 round. Bullets of sufficient strength to withstand the semi-auto feeding cycle are not likely to provide reliable expansion at Carbine velocities.

The M1 Carbine was a WW2 expedient, originally intended to fill the role of a sidearm (pistol) for support troops, vehicle crews, and other roles not directly involved in combat operations, but with greater likelihood of placing effective aimed fire within moderate ranges. Accepting the Carbine for what it was originally intended offers a greater probability of satisfaction than any fantasies about potential performance.

That said, some modest improvement in performance can be achieved by paying close attention to the fit of the rear receiver lug into the steel tang mounted to the Carbine stock, and some attention to fitting of the fore-end and barrel/stock band.

Original WW2 15-round mags do not feature a bolt-hold-open feature when the last round has been fired. Korean War issue 30-round mags do have the hold-open feature, but the hold-open function does not always work properly. Best non-USGI mags I have used have been the South Korean military-issue 30-round mags, which are the equal of USGI in my opinion. Magazine selection might be an issue for those intending to use the Carbine as a defensive piece.

I'm sure there are several factory ammo offerings with much-improved bullet designs these days, but I wouldn't get too worked up over any of them without extensive testing. Personally, I continue to hoard a 200-round supply of 1970's era Norma 110JHP's, and the majority of my Carbine shooting is done with 115-grain RNFP-GC hard cast bullets of my own production and hand-loading. About 20 years ago I came across a deal on Russian "Wolf" brand .30 Carbine ammo, Berdan primed, lacquered steel cases, 110-grain FMJ-RN, which performs very well in my Carbines. Most of my brass cases are Lake City 1960's production which have been reloaded a dozen times or more, with none showing any signs of ever wearing out.

M1 Carbines rode with me for years as a working cop, and I continue to keep one handy in the vehicle on road trips. I also keep one ready as part of my home defense plan.