OKay, so I guess this makes it a bit clearer...or as clear as one can get when it comes to these things...as to how 26" maximum OAL applies.
From:
30831Federal Register / Vol. 86, No. 110 / Thursday, June 10, 2021 / Proposed Rules
BILLING CODE 4410–FY–C
Overall Length. The overall length of
a weapon is relevant in classifying it as
a ‘‘rifle’’ or a ‘‘pistol’’ because, as a
firearm becomes excessive in length, it
is increasingly difficult to fire with one
hand. The AR-type pistol has an overall
length between 18 and 25 inches,
depending on barrel length (due to the
necessary inclusion of the buffer tube).
Other large frame pistols range between
14 and 22 inches, such as the AK-type
DRACO, HK SP5, and CZ Scorpion
EVO. Firearms possessing an overall
length between 12 and 26 inches may be
considered pistols for which a
‘‘stabilizing brace’’ could reasonably be
attached to support one-handed fire.
Firearms with an overall length of less
than 12 inches are considered too short
to indicate any need for a ‘‘stabilizing
brace.’’ Conversely, firearms exceeding
26 inches in overall length are
impractical and inaccurate to fire one
handed, even with a ‘‘stabilizing brace,’’
due to imbalance of the weapon.
So it seems that just being over 26" disqualifies the weapon from any possible compliant configuration with a brace since according to them there's no sense in even having one for the purposes of one-handed firing - the gun's too big and heavy for it. Essentially, for 'others', put a pistol buffer tube and no brace on, or start booking boating trips.