I'm really torn ..... I have a stamp for a 9mm can that will live on my Glock lower AR SBR. I keep going back and forth between 60* cones and stuffing as many as I can in a tube, and making K's. My plan is either 1.625" or 1.5" OD. Im not trying for as short as possible, but rather just long enough to do a good job. Barrel is 5.5". I would really like to keep overall length under what a standard 16" barrel would be.

I thought I had seen a decent drawing of a K here but can't find it now, maybe lost in all the photobucket issues. I'm not interested in "cups" or anything "trap" related. I have a lathe and mill.

Can folks give me some direction?

Plenty of images on your favorite search engine.

I played with quite a few K baffle designs in pistol cans. Ultimately, tightly spaced double radius clipped 60° cones outperformed all the K baffle designs. I was actually happy about that, because even though Ks are more material efficient, I can make cones in about 1/3 the time, including the indexing features.

A 1.5 x 8 running about a dozen cones with ~1/2" skirts should do quite well for you.

If you do decide to go with K baffles (allowing that ECCO is undoubtedly correct), taking an hour or more to poke around at the links in the completed build thread will be an education. Especially the last pages of the thread, as a lot of the earlier images have been lost due to various image hosting changes and user bad practice (moving images to a subfolder, deleting them, whatever).
viewtopic.php?t=79895

ECCO Machine wrote: ↑Fri Feb 28, 2020 11:32 pm I played with quite a few K baffle designs in pistol cans. Ultimately, tightly spaced double radius clipped 60° cones outperformed all the K baffle designs. I was actually happy about that, because even though Ks are more material efficient, I can make cones in about 1/3 the time, including the indexing features.

A 1.5 x 8 running about a dozen cones with ~1/2" skirts should do quite well for you.

I'm a little surprised, but also very happy to hear that. When you say "double radius clipped" I'm understanding 2 scoop type clips 180* apart. Would that be correct?

mr fixit wrote: ↑Sat Feb 29, 2020 6:33 pm When you say "double radius clipped" I'm understanding 2 scoop type clips 180* apart. Would that be correct?

Yup

ECCO Machine wrote: ↑Sun Mar 01, 2020 10:39 am Yup

Thank you sir. With that configuration, have you found blast chamber to be an issue with first round pop? I'm assuming putting the face of the blast baffle about 1/4-3/8" off the muzzle.

mr fixit wrote: ↑Mon Mar 02, 2020 4:32 pm

ECCO Machine wrote: ↑Sun Mar 01, 2020 10:39 am Yup

Thank you sir. With that configuration, have you found blast chamber to be an issue with first round pop? I'm assuming putting the face of the blast baffle about 1/4-3/8" off the muzzle.

Thereabouts for rimfire, a little more for centerfire pistol in most tubes.