Honestly from the testing I just did I think you are on the right track.  AA9 with a 200gr XTP won out with all my loads.  I tried Longshot (over book), BE-86, there wasn?t any book values for 200gr so I?m not sure if you want to go 220gr but I wasn?t impressed, Power Pistol (max book) and AA9.  AA9 was awesome and velocity well over book value without going max charge.  I think for what barrel length you have 10.4gr of AA9 is probably a good middle of the road loading.  I would lose my shit with that accuracy and have been considering a Just Right Carbine as well, good luck.

RDub01- muzzle flash was minimal with the AA9, Power Pistol was worse.  I do have some Underwood ammo left and wasn?t happy with how the bullet looked (mangled) so I will pull one apart this weekend and report back.

Alabusa- Stock recoil spring assembly, I don?t think anyone makes any options for that model and last I heard Springfield doesn?t offer it, but not sure I would change anything out if they did.  Handles everything I?ve thrown at it just fine.

New to 10mm but not so much to reloading so I went diving into the discussions to see what everyone is running.  Found tons of useful data and powders to try but mainly out of longer barrels.  I decided to do some testing on my 3.8? Springfield elite to see what the actual numbers would be.  I grabbed the usual suspects for pistol powders to try out and see what I could get without going (much) over book on charge.  I was aiming for respectable speed but with a shorter barrel and personal preference towards heavier bullets did all my hand loading with 200gr xtp?s.  I included some test results for factory stuff in 200gr just to see how it stacks up.  Definitely more room to go hotter with the BE-86 and long shot but not sure it?s needed with the AA9 results.  Any suggestions for anything that might be better?  I am very happy with a 200gr xtp doing over 1150 out of a short barrel but never hurts to try something else out.  Disclaimer- I in no way endorse anyone using above manual charges/loads and will not be held responsible for any unfortunate circumstances due to following my load data.  Work your own loads up safely!

Underwood 200gr JHP advertised Velocity- 1250fps
Chronograph avg 3 shot group- 1197fps

Federal punch 200gr JHP advertised Velocity- 1100fps
Chronograph avg 3 shot group- 1049fps

Hand loads-

All new starline brass, CCI 300 primers and Hornady 200gr XTP

BE-86- no advertised loads for 200gr, worked up to 7.0 gr
Chronograph avg 3 shot group- 1074fps
No pressure signs but probably close to what any book might say is max

AA9- couldn?t really stuff any more in there! 12.5 gr
Chronograph avg 3 shot group- 1165fps!
This was my favorite of the group, shot well with impressive speed and bullet performance

Longshot- everyone seems to go way over book for this powder but I kept it reasonable at 7.6gr
Chronograph avg 3 shot group- 1087fps
It was ok but didn?t really wow me

Power Pistol- feels and looks like it should be fast, but wasn?t, hell of a fireball at 7.6gr
Chronograph avg 3 shot group- 1077fps


I took pics of the bullets after recovery so if anyone is interested I could throw them up but I?m sure that?s been done, thanks!