Title says it all. How about a line of shields for gunners? (Defensive and health values are all relative to other similar * level shields)

Scouting Shield (2*)
Defense: Medium normal, stun resist
Health: Medium
Bonus: Low gun ASI
Description: A stealthy shield for the speedy shooter.

Scouting Shield MkII (3*)
Defense: Medium normal, stun resist
Health: Medium
Bonus: Low gun ASI
Description: An upgraded Scouting Shield ruggedly reinforced for the rigours of combat

Barrage Buckler (4*)
Defense: Medium normal, stun resist
Health: Medium
Bonus: Low gun ASI
Description: A ballistic barrier for sharpshooting snipers.

Peacemaker Pavise (5*)
Defense: High normal, stun resist (should hit visual maximum at heat level 10)
Health: High
Bonus: Medium gun damage
Description: A powerful protector used by gunslinging crusaders from an older age.

Grimshot Guard (5*)
Defense: Medium shadow/normal (equivalent to BTS)
Health: Medium
Bonus: Medium gun damage
Description: A shadowy shield for skillful agents that prefer to stay unseen.

Blitz Buckler (5*)
Defense: Medium pierce/normal (equivalent to BTS)
Health: Medium
Bonus: Medium gun ASI
Description: An upgraded Barrage Buckler incorporating sophisticated cooling technology to boost the firing rate of Spiral armaments.

The 'standard' line would be Blitz Buckler, with the other two 5*s being slightly rarer, or recipe rewards from an upcoming (Wild West themed!) boss.