For most big game species in the United States there is a minimum legal caliber where in order for a cartridge to be used for hunting it has to be of a certain size.

For example,

For all big and trophy game species, legal firearms also include any cartridge of at least .35 caliber and at least 1.5 inches in overall length, or a cartridge that generally delivers 500 foot-pounds of impact at 100 yards.


The reason is to make sure that people are using cartridges that are big enough to get a clean kill and not just wound the animal.

How is the minimum caliber determined?

  • 3
    This is state by state. No reason to assume they use a common criteria.
    – paparazzo
    Commented Jan 3, 2018 at 21:02
  • I agree with paparazzi that this varies greatly from state to state, in Texas you can use a .223 for deer yet in several other states (such as Pennsylvania) you can not. Although .223 has plenty of punch to drop a deer effectively and humanely with proper shot placement.
    – Nate W
    Commented Jan 3, 2018 at 22:56
  • 2
    I also agree with @Paparazzi that it varies by state, but much like this answer a general approach to how how the decision is made should be possible. I look forward to a good answer. I have wonder the same myself. Commented Jan 4, 2018 at 13:47

1 Answer 1


I don't have great answers, but I thought that I would post what I have found so far.

Sorry for my delay on your question and I don’t have a very good answer. It was determined by the commission with probably some input from FWP staff. It would of went out for public comment and then the commission would of voted on the proposal.

Answer I got back from the Montana Fish, Wildlife and Parks

The caliber and bullet weight restrictions were determined by what would be the minimum acceptable energy to reliably harvest an elk sized animal.

Answer I got back from the Pennsylvania Game Commision

Thank you for contacting Colorado Parks and Wildlife. Caliber restrictions are discussed, voted on, and ultimately decided by the wildlife commission. Commission meetings are open to the public and there is the opportunity for public input on issues.

Answer I got back from the Colorado Parks and Wildlife

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