I am getting my .243 threaded for a suppressor, I figured I could get it cut down too.

Whats a good length for this round? Could I cut it down to 16.5" and still have decent velocity?

I want this as a more compact deer hunting rig. Longest shot I will take is probably 300 yards.

What rifle, and what barrel length does it currently have? Sounds like overall length is your target, is it a short or long gun now (think Model 7 vs Model 700)? Personally I wouldn't cut anything under 18", and depending on the suppressor you are looking at, you might even keep it at 20".

What does your smith recommend?

Currently it is a 24" barrel Remington 700. I am going to put on a Silencerco Omega suppressor, adds about 7".

Unless it will be dedicated to using a suppressor, 22" is a very handy length for hunting.

Shorter than that and muzzle blast is very unpleasant.

I've got a couple of 243 carbines and they're both whitetail hammers. If I was cutting one down and putting a can on it, I wouldn't have any issue with an 18" barrel. They've got a little more fireball, but it's nothing that dramatic and the blast has never really been a big deal for me anyway.

My .243 is at 19" and is suppressed as well . If it's for hunting u want it about that short or else with the can it's gonna be a long beast . And don't worry about muzzle blast with a can

This is just my opinion, but I would not cut it shorter than 20", which should still maintain quite a bit of your velocity. Thats just my opinion, hopefully someone who knows more about ballistics will chime in.

Have had a couple Remington 788s with 18.5 inch barrels, they work but you are loosing velocity. The shorter you go the more you will loose per inch. If I ever get another 243 it will not be shorter barreled than 20 inches.