help with martial flexibility

[4BR4]

HI Ground,

I'm starting a Jade regent advenuture, and I'll play a crossbowman.

I'll start from lv.9 and the adventure will probably finish at lv.14

My first build was a Gunslinger Bolt Ace 5 / Fighter Weapon Master 9 riding a battle Dog and shooting a Minotaur Double Crossbow.

But then I didn't like what a 9th level of Weapon Master will offer me.

Looking for something for replace the 9th level of Weapon Master, I found the Brawler, and Martial Flexibility:

Martial Flexibility (Ex)

A brawler can take a move action to gain the benefit of a combat feat she doesn't possess. This effect lasts for 1 minute. The brawler must meet all the feat's prerequisites. She may use this ability a number of times per day equal to 3 + 1/2 her brawler level (minimum 1).

This seems fantastic to me, with the opportunity to take the needed feat for each situation.

So, I decided to go for a Gunslinger Bolt Ace 5 / Brawler 1 / Fighter Weapon Master 8

My ability scores are 8/22/14/12/20/3 and I'll go with the following feats:

1. Bolt Ace Point Blank Shot
3. Bolt Ace Rapid Reload: Minotaur Double Crossbow
4. Bolt Ace Rapid Shot
5. Bolt Ace Crossbow Mastery + Crossbow Training. Minotaur Double Crossbow
6. Brawler Martial Flexibility + Brawler's Cunning
7. Weapon Master Precise Shot + Deadly Aim
8. Weapon Master Weapon Focus
9. Weapon Master Hammer the Gap
10. Weapon Master Clustered Shot
11. Weapon Master Snap Shot
12. Weapon Master Improved Snap Shot
13. Weapon Master Combat Reflexes
14. Weapon Master Improved Initiative

Now I'd like to ask you which feats I can select with Martial Flexibility.

Right now I'm thinking to Clustered Shot until I'll reach lv.10 and I'll take it, then to Combat Reflexes between lv.12 and lv.13.

I'm not a big expert of fighter characters, so any suggestion will be appreciated.

Thank you.

[Extra Anchovies]

The Brawler level does little for your ranged combat ability. Instead, consider taking Barroom Brawler (http://www.d20pfsrd.com/feats/combat-feats/barroom-brawler-combat) and applying the Abundant Tactics Advanced Weapon Training (http://www.d20pfsrd.com/classes/core-classes/fighter#TOC-Advanced-Weapon-Training) option.

Because the Bolt Ace uses crossbows in place of firearms, ask your DM if you could do the same with Trench Fighter (http://www.d20pfsrd.com/classes/core-classes/fighter/archetypes/paizo---fighter-archetypes/trench-fighter). If they're open to it, that would let you get Dex to damage while staying single-classed Fighter (resulting in a better weapon training bonus and more Advanced Weapon/Armor Training choices).

As for which feats to pick up through Barroom Brawler or Martial Flexibility, the Item Mastery (http://www.d20pfsrd.com/feats/item-mastery-feats) feats are very nice to have available on demand. Each of them provides a magical effect a few times per day, including SLAs of Dimension Door, Fly, Dispel Magic, and See Invisibility. What's more, you get all of a feat's daily uses each time you select it for martial flexibility.

[4BR4]

Thank you for your suggestions, unluckily the Item Mastery feats are not Combat feats and cannot be selected with Martial Flexibility.

[Extra Anchovies]

Oh, right, I forgot a step! Instead of Barroom Brawler directly picking up the item mastery feat, you use it to gain Advanced Weapon Training (http://www.d20pfsrd.com/feats/combat-feats/advanced-weapon-training-combat) and select the Item Mastery AWT option, which grants one item mastery feat for which you qualify and allows the selected feat to be used with any magic weapon you wield instead of just the ones with the proper magical effects. It does require that you forgo one of your allowed instances of the AWT feat (taking something else in its stead), but for the tools it provides it's definitely worth it.