First things first, living part time in one state or another does not necessarily count as legal residency. I held dual residency in KS and MN, and then later KS and TX for some time as an adult. I owned property in all 3 states, and owned, registered, and insured vehicles in all 3 states. I also carried RESIDENT hunting licenses in all 3 states. The burden of proof always falls to the individual, so you can always expect to encounter skeptical salespersons and clerks whenever you attempt to prove residency in any state beyond that which is on your driver's license.

If you are "legally residing" in FL at the time of purchase, then no, you will have no trouble buying a long gun OR handgun in FL. However, you WILL have to provide identification showing your legal residency, which is usually the problem. The EASIEST way that I see around this, based on my own experience when I have held dual state residency, is to keep your drivers license in one state, then keep a valid RESIDENT hunting license (which qualifies as a state issued form of ID) in the other. You will have to point out to the seller that you have dual residency and need to use your FL address from your hunting license on your FTR Form 4473. By having your hunting license up front, you will have ALREADY proven your dual residency in some way, so it will look less shady to the gunshop owner, which greases the wheels. That's the method I used when I carried dual residency.

SOME STATES, have laws that their residents may only execute "pay and carry" purchases on longguns in contiguous, meaning IN residents could ONLY buy guns in IL, MI, OH, and KY.

Pay and carry handgun purchases can ONLY be executed in your home state. Does FL really count as your home state of record? See above for my simple technique.

All that said, regardless of the pay and carry restrictions and regardless whether it's a handgun or longgun, if you want to buy a gun in FL, as long as you are not prohibited from owning/purchasing said firearm in your home state, you may purchase the firearm, then have it transferred to an FFL in your home state. Usually adds about $75 to the price of the weapon ($50 shipping, $20 FFL transfer fee).