Ballistic gel is made from one of two materials: organic gelatin derived from animal collagen (typically porcine) or a synthetic polymer-based substitute. The organic version, which remains the scientific standard, is essentially unflavored powdered gelatin mixed with water at a specific ratio, then chilled into a dense block. Its density of about 1.06 to 1.08 g/cm³ closely matches human skeletal muscle at 1.04 g/cm³, which is exactly the point.
Organic Gelatin: The Standard Formula
The traditional recipe is simpler than most people expect. The FBI standard calls for a 10% concentration by weight of 250 Bloom Type A gelatin, which is a food-grade porcine gelatin powder rated for its firmness (the “Bloom” number). The rest is water. For a typical 10-kilogram block, that means roughly 1 kg of gelatin powder dissolved in about 6.5 liters of water. Some formulations also include vegetable glycerin (around 25%) to adjust the block’s mechanical properties, but the core two-ingredient version is what most ballistics labs use.
The gelatin itself is the same basic substance found in gummy candies and Jell-O, just at a much higher concentration. It’s made from collagen extracted from pig skin and bones, processed into a dry powder. The 250 Bloom rating indicates a specific gel strength. Lower Bloom numbers produce softer gels; higher numbers produce firmer ones. The 250 Bloom standard was chosen because, at the right concentration and temperature, it responds to projectile impacts almost identically to living muscle tissue.
How It’s Prepared
Making a usable block takes patience more than skill. Water is brought to a boil, then poured into a mixing container with a few drops of defoamer (to prevent air bubbles that would compromise test results). The gelatin powder is stirred in gradually and mixed until fully dissolved. After the solution cools below about 40°C, an optional preservative can be added to slow bacterial growth.
The mixture then goes into a mold and into a refrigerator. After a minimum of two hours, the gel has set enough to hold its shape, but labs typically refrigerate blocks overnight for full curing. The finished block must be tested at 4°C (about 39°F), which is a critical detail. Temperature changes the gel’s firmness significantly, and a block tested at room temperature will give very different results than one tested cold.
How Labs Verify a Block Works
Before any ammunition test, each gelatin block has to pass a calibration check. The FBI protocol fires a .177-inch steel BB at 590 feet per second (plus or minus 15 fps) into the block. If the BB penetrates between 7.5 and 9.5 centimeters (roughly 3 to 3.7 inches), the block is certified as a valid tissue simulant. A block that’s too firm or too soft gets rejected. This standardization is what makes ballistic gel useful: every properly calibrated block responds to impacts the same way, so results are comparable across different labs and tests.
The NATO Alternative: 20% Concentration
Not everyone uses the FBI’s 10% formula. NATO specifies a 20% gelatin concentration, which produces a denser, firmer block that can be tested at higher temperatures (around 10°C to 20°C rather than 4°C). The trade-off is that the two formulations don’t automatically produce equivalent results. Research published in the Journal of Forensic and Legal Medicine found that a 20% concentration of 285 Bloom gelatin at 20°C, after 100 hours of curing, matched the FBI’s calibration standard for the 10% formulation at 4°C. But other 20% combinations at lower temperatures failed to meet the same penetration criteria. Getting the concentration, Bloom rating, temperature, and curing time aligned correctly matters enormously.
Synthetic Ballistic Gel
Synthetic alternatives have become increasingly popular, especially outside of formal government testing. The best-known brand, Clear Ballistics, produces transparent polymer-based blocks that don’t require refrigeration and can be melted down and recast three to five times while maintaining consistent mechanical properties. A 2024 study in the forensic science literature confirmed that 20% synthetic gelatin is an acceptable tissue simulant for penetration testing, comparing favorably against both porcine tissue and post-mortem human subjects across hundreds of test impacts.
The synthetic version’s main advantages are practical. Organic gelatin blocks decompose. They grow mold. They need to stay refrigerated until the moment of testing. Research has shown that storing prepared organic gelatin for just four weeks significantly changes how deep projectiles penetrate, meaning old blocks give unreliable results. A preservative called methyl 4-hydroxybenzoate can slow microbial growth, but it doesn’t stop the gradual stiffening that degrades accuracy over time. Synthetic blocks, by contrast, sit on a shelf at room temperature indefinitely.
Clarity is the other big selling point. Organic gelatin is translucent and yellowish, which makes it difficult to photograph bullet paths clearly. Synthetic gel is optically clear, so high-speed cameras can capture the entire wound channel, temporary cavity expansion, and bullet fragmentation in sharp detail. For YouTube creators, ammunition reviewers, and product demonstrations, this visibility is a major reason synthetic gel dominates outside the lab.
Why Gelatin Mimics Human Tissue
The match between gelatin and muscle isn’t a coincidence. Gelatin is literally made from the same structural protein (collagen) that forms a significant component of animal connective tissue. When dissolved and set at the right concentration, it produces a material with nearly identical density to skeletal muscle. Calibrated 10% gelatin measures between 1.06 and 1.08 g/cm³, while human muscle sits at about 1.04 g/cm³. That 2 to 4% difference is close enough that a bullet passing through a properly prepared gel block creates a wound channel with the same depth, diameter, and shape as one passing through living soft tissue.
This is also why ballistic gel has uses well beyond ammunition testing. Ammunition designers use it to evaluate bullet expansion and fragmentation. Body armor manufacturers test whether their materials can reduce penetration depth below dangerous thresholds. Forensic investigators use it to reconstruct shooting incidents, matching recovered bullets to observed wound characteristics. Medical device developers test surgical instruments and implants against it. The common thread is that any field needing a safe, repeatable, ethical substitute for human muscle tissue ends up using some version of the same gelatin block.