Real-World Tips
In loading, overall length must be such it will fit easily into the magazine and also feed and chamber flawlessly. Any time I load for any semi-auto rifle or pistol, the first step is to produce a few dummy rounds to make sure they load into the magazine and chamber with no problems. For bullets I go with the Remington 110-gr. JSP, the Sierra 110-gr. JSP, the Speer 110-gr. JSP, and the Speer 100-gr. Plinker (a lead bullet in a copper cup). I also have the supply of bulk-packed 110-gr. RNFMJ bullets that work well.
I like to use factory loads as my guide. Buffalo Bore offers both 110-gr. FMJ and SP .30 Carbine loads just under 2,100 fps. The former shoots exceptionally well with groups just over 1″ for four shots at 42 yards. My most accurate loads in the Plainfield Carbine were the Remington 110-gr. JSP over 12.0 grains of #2400 (1,860 fps), the Sierra 110-gr. JSP with 14.0 grains of H110 (1,842 fps/1-1/8”), and the Speer 100-gr. Plinker over 13.0 grains of #2400 (1,950 fps/1-3/8”).
My most accurate load turned out to be one assembled with H108. With this powder, 13.0 grains under the Speer 110-gr., JSP, groups are right at an inch with a muzzle velocity of 1,825 fps. Of all the loads assembled, the slowest clocked 1,750 fps while the fastest was over 2,050 fps. All loads — no matter the bullet or the velocity — chambered and performed flawlessly. With the unknown “bulk,” 110-gr. RNFMJ performance was excellent with 13.0 grains of Accurate #9 (2,000 fps/1-1/2″).
I haven’t shot sporterized carbine as extensively yet. The most accurate loads (4 of 5 shots at 42 yards in 1-1/8″) are the Remington 110-gr. JSP over 13.0 grains of H108 (1,850 fps) and the Speer 100-gr. Plinker over 14.5 grains of H110 (1,985 fps). This Speer is one of the easiest to find and also one of the least expensive.