The 7600 bbl is not threaded into the reciever, but is "bolted" to the reciever by a stud located under the barrel opening in the front of the reciever. This bolt is usually locked by a thread locker that requires heating to remove the nut that is also tightened by a torque wrench.
A couple of years ago, I had the opportunity to tinker around with a 7400 I picked up cheap from a pawn shop that was reportedly "messed" up.
After carefully peening out some locking lug damage to the barrel hood and generally tuning it up including some massive cleaning, I got it back to full functioning without the bolt jamming open from the "peening" of the bolt against the barrel extension/hood.
It is critical to be sure that you use some type of lock-tite to re-install the barrel after removal and to torque it well, or it WILL shoot loose in short order. You'll know if it gets loose as it will group WILDLY. BTDT.
It is not a "SWAP" barrel situation either, as you'll have to headspace any new barrel, which will probably mean a different bolt head of an unknown tolerances range. I'm not familiar with any source of replacement boltheads except for Remington, which will probably require that you send the rifle to them, which will negate the option of switching barrels.
If it needs barrel replacement or servicing, contact Remington.