Greetings!
My Evan's NM Carbine has the same ".430 +/-" groove dimension. Recall that Ideal / Lyman
Outside Lubricated ("Heeled") Mould Numbers did not reflect the maximum bullet diameter, but
the Heel Diameter. One example is the Ideal #299153, which I use in my Marlin 1891; the Heel
diameter is .299", but the bore-riding surface is .313". Oddly, the .44 S&W "American" Ideal Mould
#419180 casts a .419" Heel-less bullet, while all cartridges that I've seen, and found illustrated,
were "Heeled" bullets.
Why would MH manufacture such over-bored barrels for the NM? Why would Ideal / Lyman cut
undersized moulds? So that the bullets will "ride over" heavy fouling? Eh, maybe... I'm not satisfied
with that answer, however.
"I read somewhere" (on another website, but repeated in the article above), that when the Evan's
Repeater manufacturing ceased, repeaters were assembled from existing parts; could it be that we
have NM arms with OM barrels? Hmmm... I also recall reading that some folks used .44 S&W "American"
cartridges in OM arms.
If I decide to shoot my NM Carbine, I'll likely use .41 Mag Brass, with BP, a Mag Primer,
and a Heeled bullet mould that I had custom cut years ago for my old Frank Wesson 2-Trigger rifle.
I'll use .41 Mag brass, because it chambers in my Evan's nicely, whereas none of the .44Spl, Mag, etc
brass would never chamber without extreme swaging or turning.
M.T.Marfield