How does .30-06 bullet type (FMJ vs soft-point) affect bone penetration?
Executive summary
Soft-point bullets are designed to expand on impact and therefore tend to transfer more energy into soft tissue and create larger wound cavities, while full‑metal‑jacket (FMJ) bullets are made to retain shape and commonly over‑penetrate; multiple hunting and ammunition guides summarize this tradeoff [1] [2] [3]. Sources describe soft points as offering a balance of expansion and penetration and FMJ as producing deeper, narrower wound channels and a higher risk of passing through targets [2] [3] [4].
1. Expansion vs. “ice‑pick” penetration — the core mechanical difference
Bullet construction controls whether a projectile opens up inside a target. Soft‑point (SP) and jacketed hollow‑point designs expose or thin the front lead core so the bullet mushrooms and increases diameter on entering soft tissue; that expansion “inflicts greater damage” to soft tissue compared with an FMJ [1]. By contrast, FMJ bullets are fully jacketed to hold shape and “maintain velocity,” which makes them “not uncommon[ly] … pass through game animals and leave only a small wound channel” — in short, FMJ favors straight, deep penetration over tissue disruption [2] [3].
2. What the sources say about bone interaction
Available sources do not report controlled, published datasets that isolate bone penetration differences for .30‑06 SP vs FMJ in real bone. Reporting and forum tests infer outcomes from broader terminal‑ballistics behavior: FMJ tends to “eat up” rifling and “penetrates the tissue and exits on the other side” in anecdotal accounts, while SPs are promoted because they “expand and inflict greater damage as it penetrates soft tissue” [4] [1]. Several authors caution that hitting bone can change outcomes — a soft‑point may deform prematurely on bone and fail to reach vitals in some handgun contexts, while hard FMJ or bonded cores may retain penetration after striking hard targets [5] [6].
3. Penetration is bullet design plus bullet weight and construction
Penetration depth is not just SP vs FMJ; sectional density, weight, bonding and core materials matter. Heavy, bonded or solid‑copper bullets and armor‑piercing or hard‑cored loads are specifically designed to retain mass and drive through barriers and bone — sources on .30‑06 penetration emphasize heavier bullets (180–220 gr) and bonded/solid constructions for deeper penetration [7] [8]. Guide articles stress that modern premium soft‑point designs (e.g., Nosler Partition) are engineered to expand while retaining a rear core for continued penetration through heavy shoulders or bone [9] [10].
4. Gel tests and field tests show mixed, counterintuitive outcomes
Ballistic gelatin and community gel tests reported in the sources produced unexpected results: an SP in one gel test still traversed a full 16‑inch block and fragmented, while an FMJ tumbled and stayed intact, producing a sizable cavity [11]. Authors and posters repeatedly warn “not all FMJ or SP are created equal” and that gel is an imperfect proxy for actual bone and anatomy [11] [6]. That variability underlines that simple rules (“SP always stops, FMJ always over‑penetrates”) are often incorrect in specific instances.
5. Hunting practice and legal/ethical guidance favor soft points
Hunting and ammunition guides consistently recommend soft points for game because their expansion creates larger wound cavities and more reliable, ethical kills; they note FMJ is typically reserved for range use or when deep penetration is the priority [1] [2] [3]. Some jurisdictions also restrict non‑expanding military‑style FMJ for hunting because of the higher risk of wounding rather than killing [12].
6. Practical takeaways for someone worried about bone penetration
If your explicit concern is ensuring a bullet passes through bone (shoulder girdle, heavy skulI) to reach vitals, select a bullet designed for weight retention and deep penetration: heavier grain weights, bonded cores, partition designs or solid copper/monolithic bullets are highlighted as better at holding together after striking bone [7] [8] [9]. If you prioritize immediate energy transfer and a larger wound channel in soft tissue, soft points are the recommended compromise [2] [1]. Forum and gel evidence show real‑world outcomes vary by specific load and impact scenario [11] [6].
Limitations and competing views: the available sources include ammunition makers’ guides, hunting outlets and hobbyist/forum reports rather than peer‑reviewed ballistic studies specifically comparing .30‑06 SP vs FMJ bone penetration under controlled conditions; therefore exact numerical penetration differentials for bone are not present in current reporting (not found in current reporting). Sources disagree on absolutes — some gel tests surprised experimenters by showing SP over‑penetration while FMJ fragmented — so individual load testing matters [11] [6].