I've been trying to work out the details for a non codex chapter that takes its PDF with it in larger campaigns [why not?] . I'm just quoting my post on B&C to include some statistics.

Well coming back to this idea I've changed my mind.

The scouts will be normalized to a singular company The blooding will take place before the procurement of geneseed. The surviving hundred will be implanted and armored as scouts. However there will be large detachments of storm trooper equivalent serfs attached to the chapter. They'll wear chapter colors and carry hellguns and deploy with Valkyries, Vultures, and Vendettas. For proper force interaction this means that the chapter will be focused on air supremacy and combined arms.

Marines by their nature as being non affiliated with the Imperium to a degree means that legally they can outfit a PDF.

From this, said PDF can be used offensively as a Quasi Imperial Guard under their own direction. The Ultramarines to an extent practice this with the Ultramar PDF, so in that respect this will not be a new concept.

This will lead to an extensive naval force for the transporting of their PDF. Local PDFs are allowed ships (without warp capabilities) although Imperial Guardsmen are not. As the Space Marines have their own fleet and ground forces with some loose interpreting (and some bartering for requisitions as rewards for saving forgeworlds) the marines could garner their own highly trained private navy.

A dozen Dictator class cruisers, a pair of Mars Battle Cruisers, and an Emperor Class Battleship could provide the type of assistance that the force would need.

This would form a significant battle fleet in addition to the three Battle Barges, half dozen strike cruisers and numerous escorts.

Mobilized that would give the following estimate for troop strength.

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PLANETARY DEFENSE FORCE NAVAL DISPOSITION:

--1x Emperor Class Battleship:
--2x Mars Class Battle Cruiser:
-12x Dictator Class Cruiser:
--?x Troop Transport Escorts:
--?x Fury Interceptors (Ship to Ship Fighter Craft)
--?x Starhawk Bombers (Ship to Ship Bombers)
--?x Valkyries/Vendettas/Vultures (Infantry Transports/Close Support)
--?x Marauder Bombers (Dedicated Surface Bombers)
--?x Thunderbolts (Dedicated Surface Fighter Craft)

60 Ten Thousand Man Carapace Regiments [Twelve Brigades: Six Divisions: Two Corps: 1 Army]
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SPACE MARINE NAVAL ASSETS DISPOSITION:

--3x Battle Barges:
--6x Striker Cruisers:
--2x Forge Ships:
-24x Gladius Class Frigates:
--?x Thunderhawk Gunships
--?X Thunderhawk Transporters

Containing (Approx):

300 Tactical Marines- Battle Barge
300 Tactical Marines- Battle Barge
300 Tactical Marines- Battle Barge
100 Tactical Marines- Strike Cruiser
100 Ranger (Scout)- Strike Cruiser
100 Commando (Assault)- Strike Cruiser
100 Support (Devastator)- Strike Cruiser
100 Armor (Dedicated Armor)- Strike Cruiser
100 Household (Ass. Veterans)- Strike Cruiser
40 Techmarines- Forge Ship
40 Techmarines- Forge Ship
I made the decision that 600k infantry plus support and over a thousand marines would be a great dedicated task force for protecting a pretty large area of space. Its nowhere near crusade status of course, but it would have the ability to be sustainable thanks to the borderline hive world they are drawn from.