Lead Free
Pilot Program
In 2023, the Colorado state legislature passed House Bill 23-1036, the “Nontoxic Bullet Replacement Hunting Program, .” This legislation tasked CPW with working with nongovernmental partners to design a two-year ‘pilot’ program to encourage hunters to voluntarily switch to lead-free ammunition. CPW and partners have met monthly to develop outreach and educational materials for hunters, coordinate strategies and communications, and provide range demonstrations. In fall 2025, a targeted sample of deer and elk rifle hunters will be surveyed on their use and opinions of lead-free ammunition. A report will be available in 2026.
No new regulations on lead ammunition have been enacted. This resource is meant to provide what we believe is the most relevant information for making a fully informed individual choice.
Crowd at a CPW hosted lead-free demonstration at Cameo Shooting Range
Comparing Lead with Lead-Free Ammo
An effective, high-performance round is one of the most important factors in a clean, ethical harvest. Most traditional rounds used by hunters are made of two materials: a lead core and a copper jacket. Some rounds are made of a single metal, often copper, for big and small game; steel, bismuth and tungsten are used for waterfowl and upland birds.
Colorado Parks and Wildlife has hosted range demonstrations, comparing the performance of lead and copper ammo using ballistics gels . Using ballistics gels representatives from Sporting Lead-Free and the North American Non-lead Partnership have shown the difference. These gels are excellent models for living animals, as they imitate muscles and vital organs very closely.
Fragmentation
When a lead bullet hits ballistics gel, it loses weight as it mushrooms out, leaving small pieces of lead along its path. In one demonstration, lead bullets lost 30% of their weight after impact; copper bullets remained almost entirely intact, losing only 1% of their weight, but still mushroomed. Lead is softer than other expandable bullets and erodes extra fragments.Copper bullets don’t leave lead fragments behind.
Swift, Ethical Kill
While it’s commonly believed the amount of weight loss and fragmentation lead bullets undergo is necessary to do enough damage to down a big-game animal, this is not true. The bullet paths visible in the gels show that lead and copper bullets both expand into a mushroom shape, creating a broad pathway, and radiate enough energy into the animal for a swift, ethical kill. In fact, the weight that copper bullets maintain actually provides superior penetration compared to lead, ensuring a clean harvest.
Efficiency
After being hit in the heart or lungs with an effective, well-placed, humane gunshot, a big-game animal tends to travel a certain distance — its “standardized animal flight distance” — before it collapses. Research has shown that moose, brown bear, red deer (similar to elk) and roe deer all travel their standardized flight distances whether shot with a lead or copper bullet: Neither type causes excessive suffering.
Cost and Availability
Mid- and top-tier rifle ammo, whether lead or lead free, are comparable in price. Lead-free ammunition, both as loaded ammunition and bullets for reloading, is available in all popular calibers through many manufacturers.Lead-free is often available at local stores and online. Plan in advance to make sure you have ammunition in time for your hunt.
Lead Concerns
Beyond the Bullet
Because lead bullets fragment on impact, tiny pieces of lead are left along the bullet's path through the animal but some can spread much farther. Hunters pride themselves on leaving the land better than they found it. As conservationists committed to protecting natural heritage, many hunters are choosing lead-free ammunition to benefit wildlife and support healthy ecosystems.
Lead fragments are often so small we don’t notice them as we’re preparing, cooking or even chewing meat. Confirmed lead fragments are found in approximately 20% of ground game meat.
Talk to your doctor if you’re concerned about the effects of lead on you or your family’s health.
Learn more about how lead affects human health:
Lead-based ammo can have negative effects on nontarget wildlife.
- Gut piles can be a great source of food in the fall and winter months for raptors like eagles and hawks. Mammals like foxes, fishers and black bears will also partake. It’s one of the innumerable benefits of hunting: Nothing goes to waste.
- Even when a big-game animal is shot through the heart or the lungs, the gut pile left after field dressing can contain stray fragments of lead. A lead fragment as small as 20 mg, about the size of a grain of rice, can be fatal to an eagle.
- Lead is well known as a neurotoxin, a substance that causes brain damage. As it dissolves in the stomach and is absorbed into the bloodstream, tissues and bones, lead harms the nervous system. Animals can suffer tremors, convulsions, delays in brain development, poor coordination, stomach muscle paralysis and even death.
- Because lead stays in the bloodstream temporarily, blood lead level is an accurate indicator of recent lead exposure. Though it exits the bloodstream after a short period, lead never leaves the body, accumulating in the bones over the animal’s lifetime.
- Lead-free ammo reduces lead exposure in raptors. In one experiment, scientists distributed lead-free ammo to hunters for two seasons and measured the blood lead levels of bald eagles in the area. They found that when more hunters used lead-free ammo, blood lead levels in the local eagle population decreased.
- Many research studies from across the globe have shown that blood lead levels in raptors are higher during big-game hunting seasons, with lead from gut piles as a major source of lead exposure.
- Even a perfect shot can leave lead fragments in the gut pile of an elk, deer, moose or other big-game animal. Lead fragments can travel as much as 18 inches away from the main wound channel, making it impossible to remove all lead from the meat or gut pile.
Choosing What's Right for You
If going lead free is right for you, here are some ways to make a smooth transition.
Making the Switch
Because lead is heavier, you’ll have to adjust for bullet weight when switching to copper to maintain performance. Start with copper bullets one grain weight lighter than the lead bullets you currently shoot. Every bullet type has limitations. Know what your ammo is capable of and use it accordingly.
Learn MoreSticking with Lead
There are ways to mitigate the negative effects if you choose to continue using lead. Use high-quality hunting-grade ammo with a “bonded” or “partition” construction. These bullets still fragment and can pose a risk, but they usually fragment less than the typical “cup-and-core” lead bullet. Bury or pack out gut piles and other remains to prevent nontarget wildlife from ingesting lead.
Shooting Activities
Even if you decide to hunt lead free, lead can still be a great option for shooting practice. Shooting ranges, like those administered by CPW, have standards that mitigate lead impacts at the range.
Resources
Learn more about lead-free hunting by visiting our partner websites