Sabots
Plastic / nylon sabots are still around. Google sabot accellerator and you should find some hits.
A few points you may want to consider:
1: not for short range
Sabots take between 25 to 50 yards to reliably separate from their payload.
2: crown critical
These things begin to open up upon leaving the muzzle. The crown of your rifle is critical to accuracy.
3: squeaky clean!
Sabots LOVE squaky clean, no fouling, fresh bare steel barrels. The plastic they are made of is softer than the copper that could be fouling the rifling of a barrel, and that fouling can and will scrape and cause irregularities in the sabot that can impact accuracy.
4: Twist!
Be sure that you are stabelizing the sub caliber payload properly, or accuracy may suffer!
5: Muzzle break
I have heard no definite reports, but it seems a bad idea to fire this flowering, expanding bit of nylon through a baffled muzzle break. This, by the way, is the reason I still havn't tried a .50 sabot down to .30. Imagine, 4900 FPS with a 250 Gr .308 bullet! But without a really good break, kiss your shoulder goodbye! Maybe in a really big railgun type setup, but not shoulder fired!
