The third part of the PoliceOne study that 03RN linked above:
Ballistic gelatin v. clear gel, part 3
The conclusions are not unexpected: Clear gelatin overstates penetration and understates expansion. It should be noted that none of the Clear Gel blocks met calibration standards, with the calibration BB penetrating an average of 25% farther than the standards allow. In theory, we could just apply a 25% correction, but that doesn't seem to be the case.
Testing showed that the overpenetration averages 35.5% in the bare test (range 34.4 - 36.3%), but 48% deeper in the clothed test, with a rather wide range of 38 - 56% more penetration in clear gelatin than in calibrated ballistic gel. Compare that to the more limited Brass Fetcher findings of 20 - 25% deeper penetration in bare clear gel (study liked above by 03RN).
So, despite my hopes, there is no apparent reliable "correction factor" from these tests. Clear gelatin will show a penetration increase of anything from a couple inches to 6 inches greater than calibrated ballistic gelatin. The
sine qua non of a useful test medium is reproducibility. Ballistic gelatin is definitely a bit of a PITA regarding preparation and handling, and many still argue against the validity of "jello testing", but it doesn't look like clear gel is a viable substitute at this point.