I got my stamp back and I need to setup my spacer and cone stack in the 5.8” tube I have (technically 6" with the end caps). I am using the 1.355” ti skirtless cones from totality and want to use 8 cones, at least (first 3 steel the rest ti). It will be mounted with a Griffin Armament flash comp taper mount.

I would appreciate help determining the space I need for the expansion chamber, spacers and cone setup to get optimal performance.

The build is listed as a .308 but I anticipate it being used mostly for 5.56/.223 on a 10.5" barrel.

You don't have enough space for 8 baffles.
Your 5.8" tube, minus the endcap thicknesses, will yield approx 4.75" internal length. Less if your threads are >1/2" LG
You'll want around 2" for a blast chamber, especially for a 10.5" 5.56mm or 308 setup. This would give you approx 1-1/8" for a muzzle device (with cone almost touching device) or 3/4-7/8" for device w/ space to Blast Cone.
This leaves approx 2.75" for cones. 8, 3/8" spacers would need 3".

If this was a dedicated 5.56mm design, I'd say a .375-.4 baffle spacing would suffice. Since you might use this on 308, I'd try to keep the spacing closer to 7/16-1/2".

What kind of cones, straight 60 degree, or curved radial cones?  Many radials have a minimal close spacing and won't stack as close as straight 60 degree cones.

You are going to have a hard time getting 8 cones into that short of a tube and that long of a muzzle device.  Your blast baffle tip can be as close as an eight of an inch off the muzzle device.  You can experiment with card board tube spacers to get this spacing.  I'd guess close to 2.5".

The SiCo Omega 300 with very thin and contoured baffles gets uniform spacing as fine as 0.375". Commercial cans go with uniform spacing for economical parts and assembly.  Fewer baffles with more spacing can work well. Generally the first spacing at 0.75" and closer spacing as you move toward the front cap.  A larger space between the last baffle and the front cap is nice to have but if necessary you can have that last cone butt right up to the cap threads.

You can lay it out on paper and then when cutting spacers adjust the blast baffle spacer or first spacer to get it all to fit tight.

I'll be using straight 60 degree skirtless cones from Totality.

Is is better to have more cones with less space or less cones with more space?

Efficient baffles with turbulence inducing clips is the most important design feature once a given tube size and volume are fixed.  There are suppressors from 10 years ago with only 3 baffles that don't sound too bad.  I believe a Sandman S has 5 baffles, Thunderbeast Ultra 7 has 6, the Griffin Optimus Micro only has 5 in a narrow tube.  I've also heard freeze plug cans stuffed full of cones that do ok but those are longer than yours.  Sixty degree cones theoretically can pack so close that you have no void volume off the bore so there is a point of diminishing returns.  More baffles take up space but they also provide a heat sink.  More baffles makes sense in a longer tube as there isnt just space for them, but more time before the bullets uncorks the front cap.

You can gain some space by using a flatter blast baffle or a cone that starts smaller inside a 'hat' brim.  Then a .75" first spacer, then half inch from there on out. You might be able to get 6 baffles, but even 5 good baffles can do well.

Is there a minimum recommended spacing?

I've worked with the folks at Totality and they've been great. I have a spacing for a 5 cone tube.

However, they have a 7 come kit and I could reduce the width of the spacers from .375 to enough to fit the other two cones.

I just don't know if this would hurt performance or cause pressure issues?

Honestly if don't know if there's a minimal spacing where the clips on the cone tips stop working as well.

The more you pack into the can the void volume goes down.  So less volume theoretically will increase pressure. But realistically the highest pressure is in the blast chamber and drops rapidly in time and distance after that. In a non-welded can the blast chamber pressure 'thrust' is transmitted down the stack and born by the threads of the front cap and rear as well. Reducing the post blast baffle can volume just means the slope of pressure decrease has a flat spot and a rapid drop to ambient. Your can holds pressure a little longer and releases a higher pressure faster, making it potentially louder.  This effect could be minimal if only adding the volume of 2-3 cones. So I'd be more concerned how putting the cone tips closer together impacts gas flow.  I've never seen designs packed closer than 0.375" spacing but maybe 0.275" also works fine.

Maybe Rusty has had some experience with this.

@Rustyand

I agree with your assessment. I just finished a build for a 9mm on a 1.5 x 5.8" tube. It is a handgun can with a booster so the blast baffle tip was only .2 off the booster tip. The bc spacer is .780. To get 6 baffles in I used an rsc as the first and last baffles since the rsc are .230 shorter than the totality cones.  The spacers are as follows .650, .625, .600, .560, .500, 375, and .400 between the endcap and last baffle.

For the op can using a ga flashcomp will be very restictive. The flashcomp is 2.375 long and protrudes in the can 1.750 past the base of the thread adapter. The totality cone is .650 tall. So we add .650+1.750. .250 (past the flashcomp tip) so the bc spacer will be 2.5 long. The overall tube is 5.8" - the endcap and thread adapter. 440 each subtract .880. You are left with 5.8 -.880 - 2.5 = 2.42 for the rset of the cones. Using .60 for the base of the cone to support the spacers. For 6 cones is .360. 2.42 -.360 = 2.02. Using 5 .375 spacers leaves .125 spacer for the last spacer between the cone and endcap.

Imho this would not be a very effective rifle can. I have built a 5.8 tube using all rsc allows longer spacers that did turn good but used a ga minimalist brake also.

Using the GA minimalist gains approx 1 inch of extra spacing. Using a shorter cone could gain another 1" of spacing which would improve the overall performance.

Theoretically, could a suppressor designed for a 2.375 flash comp work on another rifle with a GA minimalist?  In other words, if I already have a flash comp and want to buy a GA minimalist for another rifle can I design a suppressor that works with both muzzle devices?

If I Understand what you are asking, a minimalist in that blast chamber woukd just increase the distance from the tip of the muzzle device to the blast baffle tip. Shouldn't be an issue of fit, and I Doubt you'd hear any difference.

Yep, that's what I was wondering, and I'm sure it's sort of a basic question but I just wanted to make sure I wasn't trapped into buying one length of muzzle attachment for multiple rifles that will see this particular can.  Thanks!