deux à deux

11:37 Apr 15, 2021 

Quite right, reading patents is not always obvious, even the first part of this sentence ¬"tir du projectile dans l`arme" is bizarre. We are not firing the projectile into the weapon.
Fitting the sabot in pairs would make sense, i.e. two halves fitted around the rod and not slid over the length of the rod.

11:35 Apr 15, 2021 

Well explained!
I'd see it as "one to another", which would cover most instances, and certainly fit the logic of the explanations.

11:09 Apr 15, 2021 

To me, 'two by two' would suggest that the parts are joined together in pairs rather than each section of the sabot being connected to the neighbouring section - but then again, this is a patent and I find it difficult to get my head round the wording in patents sometimes. The way the pieces of the sabot are connected can be seen in this video. https://www.youtube.com/watch?v=yHbf-Eb3xak (just after 1min in)

Here, 'deux à deux' is translated as 'with each other' -

"Théorème 4.1.8. Soit X un espace de Banach, et 1 ≤ p ≤ +∞, p 6= 2. On a :
(i) Les éléments de Pp(X) commutent deux à deux...
Theorem 4.1.8. Let X be a Banach space, and 1 ≤ p ≤ +∞, p 6= 2. We then have
(i) All elements of Pp(X) commute with each other"

http://perso.eleves.ens-rennes.fr/~vaign357/Recherche/Memoir...

Here, 'deux à deux' is translated as 'from each other'

"get arbitrarily far separated from each other...s’éloignent asymptotiquement deux à deux"

http://www.numdam.org/article/AIHPA_1985__42_1_39_0.pdf

I have seen it translated as 'pairwise' in this summary of mathematical English.
https://webusers.imj-prg.fr/~jan.nekovar/co/en/en.pdf