considering chopping my 6.5 tikka t3x barrel down to 16.5-18 inches.

I have seen this talked about in a few threads just wondering if anyone has done it and if they have regrets.

I am looking at making the rifle handier.

The 6.5 is intended to be a long range cartridge. While you could cut back the Tikka it might be a better choice to pick up a Ruger American in a 16in version like 7.62x39 or 300 BLK or .223 which lend themselves to working with that length barrel .  Or pick up a lever action 44 mag, 45-70 etc with a 16 in.

Im not sure what length the barrel is currently....   If its a 24", I can see the reason for the cut.  If its a 20" , its not worth it...

Ive been hunting with 20" for years with.a whole raft of carbine barrels in 260, 7mm08, 308 and others.  They make for handy little carbines.  Compared to.a 24", youre probably going to see something luke a 100 to 125 fps velocity loss.  Its not huge, but its there.  Is what it is....  The 6.5 Creed isnt a speedy cartridge in the first place.  Factory Hornady 143 eldx loads are chrono-ing roughly 2600 out of my 20" Tikka CTR....

I would not go shorter than 20".   Yeah, I know lots of AR's are running 14.5 and 16",  but 5.56 is not something like 6.5CM, 7mm08 308.etc...  I have not fired 16" 6.5 creeds but have fired 16.5" 7mm 08 and others.  The blast, fireball, and concussive sort of experience is not pleasant.  With.16" barrels you dont gain much handiness but you give up velocity and gain harsher shooting.  

20, 21" is about optimal for these medium capacity cases.  Just my two cents....

Take a 24" down to 20"?  Absolutely.  Take it to 18, 16"?  Hard no.

https://rifleshooter.com/2016/02/6-5-creedmoor-effect-of-barrel-length-on-velocity-cutting-up-a-creedmoor/?fbclid=IwAR3OJcojo6bKRvSs6zt3ttATc0rvwpY04uxdQ5WZ5LRhtITCaRljoifmWvI

I was worried about it as well but looked it up.

I have 6.5s in 24,20,18, and 16.  

If you're suppressed, DO IT!   If you're not suppressed, don't put a stupid brake on it and DO IT!

If it's for hunting, you're still carrying 1000ft/lbs well past 500yrds with a 140 class bullet.   None of the AR-15 sized calibers are doing that from a 16"

You're losing less than 200fps going from 24" to 16".

ETA  I just got a TC compass compact in 6.5 with the 16" for $310 after rebate. I can't believe how much I enjoy this handy little thing.  It's going into the deer hunting rotation this opening weekend.  With multiple tags and 9 days off it should get a chance to kill something.

OP, did you end up chopping the barrel? I just bought a T3X in 6.5CM with the same idea in mind. Planning for it to be my main hunting rifle and will always be shot suppressed so I was looking to go 16.5" with suppressor total length is 23".
With 120gr. class factory loads ballistics are good out to ~425-450 yards for deer-sized game. With 143gr. class factory loads ballistics are good out to ~475yards at 1900fps or ~575 yards for >1000ft.lbs. or ~250 yards for elk-sized game/1500ft.lbs. Seems like plenty of capability for a hunting gun. I think "long-range" hunting is fine if the shooter is experienced enough but I think the better option is just to get a bit closer then shoot. Doesn't seem like I'm neutering the cartridge too badly for my intended use.

So, I ended up doing it... Got a 24" T3X Lite and am chopping it to 16". I used Berger's Stability Calculator and Hornady's Ballistics Calculator to rough out around a dozen different factory hunting loads and I'm getting plenty performance out of the 16" for my skill level and desires. Can't wait to see how nimble it is. If I remember, I'll try to post some before and after pics.