In brief, strict scrutiny is the most stringent level of scrutiny, and rational basis the least stringent. Operating a vehicle on public roads is decidedly a right, but not a constitutionally enumerated one, so it is only held to rational basis. Rational basis scrutiny allows a right to be curtailed it, on a rational level, the curtilage is related to a legitimate government interest.

When strict scrutiny is applied, it means that a much more stringent justification must be met. Not only must it further a legitimate government interest, but it must also be the least restrictive possible means of doing so, and not fundamentally burden the right.

Banning teflon coated bullets does not fundamentally infringe the right, and is narrowly tailored enough that it survives the least restrictive means test. Banning all ammunition cripples the right, fundamentally, and is nowhere near tailored enough to survive heightened levels of scrutiny.

Just to nit pick it is not teflon coated bullets that are banned (at the federal level), but bullets made of certain hardened materials that are banned. The teflon is there just to stop the gun barrel being damaged.

I am not suggesting banning all ammunition (as a tactic), but degrading the killing power of bullets by legislating what they can be made from and how fast they can leave the muzzle. How much could the killing power of bullets be degraded before the law would be considered an infringement on the second amendment?