sister was pulled over for stupid reason (don't want to write)
The reason does not matter, so long as it was a legitimate violation.
Officer asked if she had any guns or drugs. She said no drugs, but there is probably gun that is her husband's (he is hunter) and there ispermit and gun is legal.
The correct answer was "No".
Whether or not the gun was legally owned, there are still laws regarding the transport of weapons that she may have been in violation of. As the driver, she is responsible for EVERYTHING in that car, whether she owns it or not.
They searched car for 15 minutes - would not let her be near the car while they did it.
This suggests the gun was concealed- probably in a false compartment.
Did she consent to the search? (She probably did without realizing it)
Did she at any time tell the officers to stop searching? (believe it or not you can do that, though if they have good cause they can hold the vehicle while they attempt to get a warrant)
They then said they found loaded weapon. Falsely accused.
Well did they find one or didn't they? Are you saying they planted one or are you saying that what they found wasn't loaded?
In report they wrote they stopped her because seat belt not the original reason they told her they were pulling her over - so they lied in their report.
Was she wearing her seatbelt? Perhaps there were multiple reasons for the stop.
They did not read her rights
This would not have been necessary unless they continued to question her after she was taken into custody. She was not arrested until after the gun was found, and by then they likely had all the info they needed- so I wouldn't be surprised if they did not ask more questions. She already told them she knew a gun was in the car and then they found one.
they would not let her make phone call when she asked.
Nor should they.... was she going to call in the troops to come rescue her? For officer safety reasons cell phones are often separated from their owners while they are being detained- or they are otherwise not permitted to make calls. The last thing the police want is a bunch of friends and family showing up to complicate things.
They questioned her for a while - she kept telling her innocence. They took her to jail.
They found a loaded weapon in the car. She wasn't innocent- unless you are suggesting they planted it.
The nature and timing of the questions could determine whether Miranda was required or not, though it sounds like she was questioned while detained during the search.
She's out on bail. We have trial date. Please help us - we need good lawyer to fight this injustice - they can't do this to people - we have very little faith in our system if this can even happen, we are afraid.
Hire an attorney and plead not guilty. Make them prove their case.