...she is the only one to blame for her pain if she is raped...
Poor choices can have unpleasant consequences, but that's entirely different from assigning blame.
Saying she's to blame for her pain is all kinds of messed up. The person who committed the crime and caused her pain is to blame, not she.
If I forget to lock my door when I leave for work in the morning and someone walks in and takes my TV, I will bear the unpleasant consequences of my inattention. But I'm not to blame for the fact that a thief decided to perpetrate a crime against me. The burglar is to blame for committing the crime.
If I sell a gun to an apparently qualified person who uses the gun in a crime, I am not to blame for his criminal behavior or the results of it as long as I complied with the laws that govern the sale of firearms between non-dealers. The person who purchased the gun from me and chose to use it in a crime is to blame.
Would you expect it to happen?
Expectaction is not a reasonable criteria for assigning the blame for criminal acts. We can always expect criminals to commit crimes, but the fact that we don't take every possible precaution to prevent crime doesn't mean we're to blame when we fall victim to crime.
Criminals are to blame for criminal behavior and the results of it. It's fashionable in our society to try to shift blame for various reasons but that doesn't mean it makes sense or that it's the right thing to do.
Hodgdon puts its products on the market in an unsafe manner.
No, that's an overstatement. Hogdon may not have taken every possible step to prevent someone from tampering with their product, but that doesn't mean their product is "on the market in an unsafe manner". We are not required to take every possible step to prevent crime or to avoid being targeted by crime before we can escape being blamed for crime. We simply have to avoid committing crime to avoid being blamed for crime.
And that's a very fortunate thing. If that weren't the way things are, who would be given the power to "create crimes" that aren't on the books by deciding when someone is not doing enough to prevent people from committing crimes and is therefore to blame for the crimes? We have enough laws and rules to assign blame; we don't need to make up new ways to blame people for crime. Especially people who haven't done anything worthy of being blamed for crime.
Part of the problem with our society is that people aren't satisfied unless they can find someone to blame even when the real culprit isn't available. The person to blame for this situation is whoever mixed the powders and resealed the container. The fact that he can't be located doesn't make it right/reasonable/acceptable to try to blame Hogdon for what he did by trying to make it look like they're culpable for not making it impossible to tamper with their product.
Hogdon is as much a victim as cornbush. Moreso, in fact. He's out only the cost of a few rounds of ammunition and a canister of powder. They are out the cost of a new rifle and in addition to that, they are now being blamed because someone tampered with one of their products and resealed the container.