Exactly - set up your FL die to only partially size the body and just barely all of the neck, but not quite.
If you don't push the shoulder back each time, your brass will last a LOT longer.
The cases should be annealed about every 4 to 5 shots or so.
I would suggest they should last upwards of 20 shots each, if cared for.
The reason for partial sizing only.
Belted magnum chambers are usually long in the body length as the case supposedly headspaces on the belt.
Due to this over length body, once a case is fired, it stretches forward at the web to 'fill' the chamber.
If you bump the shell holder against the die, you will likely push the shoulder back down again (short die body). Reloading and firing again, again stretches the case at the web - thus the case get thinner and thinner at the web and case life of 4 shots or less is common with many belted magnums. This is less of a problem with rimless cases, as chambers are held to tighter standards as the body is the headspace for that style of ctg. In Europe the headspace laws are very similar to the SAMMI suggestions of .006" maximum.
That means with a belted case, only the distance from the base to the front of the belt needs to be within this limit. The body does not matter. Many mfg'ers are sloppy with the body measurement on the reamers. They do not care about handloading- especially if they sell ammunition as well.