Get yourself one of the Lee Collet neck sizing dies, they aren't expensive, and give it a try.
When I first started reloading I had a nightmare with neck sizing and eventually came to the conclusion that either the die I was using was faulty or I was doing something really stupid wrong even though I believed I was following the instructions.
I bought the Lee die more on a whim and haven't used anything else since. I did once full length size a small batch of my brass as I thought maybe one of my reloads required a bit more force than usual to close the bolt. However, I have other brass that must have a lot more loadings on it that has never been full length sized so maybe this was me looking for a problem rather than a real event.
I'd heard that I would have to full length size every 4 - 5 loadings but apart from that one incident I haven't found that to be true. I don't count the reloadings on my brass and so am not totally sure but I know how many primers I have gone through and that I've only recently added some new brass to my original lot of 100 Lapua and the numbers tell me that on average my brass must have 10 reloads on it, though some got used more than others. It is several years since the full length die was last out of the box and even then it was only a small batch that it was used on so at the very least I must have brass with over 5 neck sizing events without full length sizing on it and I'd be pretty sure there is some brass in there that most be over 10.
So, it is worth giving it a go. For me I love not having to mess about with lube on the cases, and then cleaning it off and that makes neck sizing worthwhile.