You can definitely make sabots hold on long enough to get past the end of the suppressor and that's really all that matters 

All you really need is something to keep the sabot in place until it's clear of the bore. I've seen pictures of shotgun suppressors around, where the bore is lined with guide rods to do just that. For a rifled barrel you'll want these surfaces to match the rifling.

As for the polymers and pressure, they should be fine. Thirty years ago sabot polymers weren't adequate for service, but they did what they needed to most of the time. These days it shouldn't be too hard to formulate a polymer with the exact characteristics you need. You can do FEAs to figure out what those characteristics are, and do computational chemistry to figure out how to get them. (Computers really are something, aren't they?)

Yeah I know of some guys who have done FEA's on a few sabot designs that look pretty favorable from a strength, function, and parasitic mass stand point (as low as 5% sabot weight to projectile weight) 

It's just a matter of getting everything together to start testing and small scale prototyping at this point.

There's a whole bunch of stuff that's absolutely possible, it's just a matter of the will and funding to get it past the digital validation phase.

All we need now is for the real Elon Musket to stand up and deliver us from this archaic status quo. 

Or something similar sure.

There's kinda no denying that we have a problem at this point.

How we solve it is not my department though.

Revive Springfield Armory.

Regarding l/d ratio, the FN 15mm had really long bullets for their APDS....look at the pics.

Im unsure as to whether a 4mm steel rod would be best (no jacket) or perhaps add a jacket to increase it to 5mm

and as as for expensive tungsten, why not blend it with a steel alloy so your only using 15 grains of tungsten

Lol Springfield was the epicenter of the worst of the worst unfortunately Stan.

The shenanigans they pulled and the good designs they screwed us out of are legendary in their own right.

You can drastically outperforn a light 5mm, go with a .22 or 6mm thats only 45grains, with an ogive long enough to retain the BC.

if you can solve the barrel wear issues, you have a 3800-4300fps round.  And no heavier than 556 with alum or poly case.

I noted that the 6mm unified, 30mm GAU, and some others have SUCCESFULLY used aluminum cases...how did they solve the problems i wonder

smg762 said:

Regarding l/d ratio, the FN 15mm had really long bullets for their APDS....look at the pics.

I did, and that is indeed a 5-ish calibre long projectile. And I don't remember that project being cancelled for something other than the sudden lack of a need for a weapon that outperforms .50 BMG but isn't an autocannon yet. That sabot is a lot bigger relatively than you'd want for an infantry weapon though.