GAJO Games published WW1 adaptations, which are a good starting point for Bolt Action v2 (
http://gajominis.com/rules/rulesgajo.html). I totally endorse the point that 'the [Bolt Action] rules as published do not need significant changes to reflect World War One actions'. Here are some additional comments and suggestions, FWIIW:
1. Air Support was divided into two broad categories:
a. Artillery fire control, typically controlled by aerial observers in aircraft and/or captive balloons. Normally this type of fire was directed at enemy forces identified off-table. Firing at enemy in close combat with friendly forces, which is what Bolt Action represents, was not encouraged because of the very high risk of blue-on-blue. That said, Bolt Action is about introducing a taste of some of these elements of battle. The variant, as described, is ok from this perspective bearing in mind that the Air Force Forward Observer would actually have been in the air in reality.
b. Strafing and low level bombing runs from ground attack aircraft. Fighters and dedicated fighter-bombers began operating this way in 1916.
2. The Chauchat LMG has been given a 'jam' Special Rule. All LMGs were prone to this in muddy conditions. There is a famous video of a German MG08/15 being set up and fired in a training exercise. It jams multiple times in the minute or so of the clip. The French army conducted a thorough review of all weapons systems, including the Chauchat, when Pétain took over in 1917. There were lots of positive reports about the Chauchat. The issue of maintaining cleanliness during battle was emphasised but this was not unique to the Chauchat. Furthermore, the Chauchat was highly prized by Stosstruppen, who would receive financial and other rewards for capturing these weapons for re-use in their units. I recommend not using this Special Rule.
3. 'Infiltration Tactics' are frequently referred to in relation to German Sturmtruppen. The term is used to imply that units could slip between frontline defences. The attacks on British Fifth Army during Operation Michael in March 1918 are often cited as an example. The 'infiltration' achieved by German attackers was not down to something inherent in the units themselves. It represented the very dispersed nature of the British defences. In other words, you would model this by spreading out the defender rather than apply a Special Rule to the attacker. Operation Mars was a complete failure because 'Infiltration Tactics' could not work against normal defences.
4. Mk V* (often referred to as Mark Five Star). Apply the same stats as the Mk V but add the 'transporter' Special Rule. It transported MMG teams. The A7V transported a wider range of assault troops.
5. Captured Weapons - also allow the Germans to swap for the Chauchat LMG. The Madsen LMG can also be used.
6. Stosstruppen, Elite Stormtrooper, and Assault Squads should not have different Special Rules from their British, Dominion, and French counterparts. German histories refer to these counterparts as 'Sturmtruppen', reflecting the similar nature of assault tactics across all major nations on the Western Front.
7. Granatwerfer should have 3 crew, mirroring the requirements for the 37mm Infantry Gun Team.
8. Americans and French should have the Schneider as an option: 1 x MMG on each side; 1 x light howitzer - otherwise same as Char St Chamond Tank. Note that French tank forces used pioneers to turn difficult terrain into 'normal' terrain.
9. All tanks can disembark MMG teams when bogged.
10. The French should have the equivalent of 'elite' assault troops, reflecting the dedicated assault teams and/or the use of colonial troops such as the Sengalese for this capability.
11. Bergmann SMGs were very rare. I would leave them out or make them much more expensive to include in a squad.
12. Flammenwerfer are better modelled as separate teams IMHO. The French and Americans should have an option to include dedicated flamethrower teams as well (French flamethrower teams were attached to the Americans, eg the Big Red One's attack on Cantigny).
Robert