While copying from 𝓞 to 𝓟, Oliver Cowdery accidentally replaced the singular murmuring with the plural murmurings. This error may have been influenced by the immediately preceding plural form journeyings. The plural noun form journeyings itself is undoubtedly correct; the text prefers the plural journeyings over the singular noun journeying ( 7 to 1).
Elsewhere the text has a variety of examples with the gerundive verbal following the preposition without:
Thus in 1 Nephi 17:2, the singular murmuring in 𝓞 should be accepted as a gerundive verbal since it is preceded by without. On the other hand, the count noun murmuring(s) is always in the plural; for discussion, see 1 Nephi 16:25.
Summary: Restore the gerundive murmuring in 1 Nephi 17:2; the gerundive verbal is perfectly acceptable after the preposition without.