short barrel choke?

[Franklin7x57]

Looking to add a Mossberg mini bantam with a 18.5" barrel in 20 ga. My question is does the short barrel change which choke you would choose?  I'm not looking for the tightest core, I really spend more time studying the 20" circle than the 10".
If you had a 26"- and 20"-barrel shooting the choke, would you expect similar patterns? I know it really depends lol. I'm shooting an affinity 3 20 ga. 26" barrel, a Trulock .585 and I'm pleased with the pattern. I'm shooting TSS 

[compton30]

Looking to add a Mossberg mini bantam with a 18.5" barrel in 20 ga. My question is does the short barrel change which choke you would choose?  I'm not looking for the tightest core, I really spend more time studying the 20" circle than the 10".
If you had a 26"- and 20"-barrel shooting the choke, would you expect similar patterns? I know it really depends lol. I'm shooting an affinity 3 20 ga. 26" barrel, a Trulock .585 and I'm pleased with the pattern. I'm shooting TSS

Give Mr. Sumtoy a call and he'll get you lined out on this. He may even see this and respond just because he's an active member of the forum

[Ihuntoldschool]

Anytime you change anything patterns likely to change.

Barrel length included. Also load, fast powder vs slow powder, velocity, wad, buffering, crimp , ported vs non ported..  Anything.

You're changing choke systems so won't necessarily get same patterns as you got before. 

Start in 575 to 585 range and experiment from there as needed. 

Barrel harmonics , vibrations change short vs long barrel as well.