"Ringing the neck" may happen when any filler is used in bottleneck cases. The filler is pushed forward into the neck by the initial ignition before being consumed with the powder. An actual ring will form at the base of the bullet in the rifles chamber neck. If severe enough the ring can affect...
You might want to try polyfill that is used in the sewing crafts for stuffing pillows. All that is needed is about one grain by weight or just a small pinch.
Do not use it in bottlenecked cases. There is a real possibility of ringing the neck in your chamber.
You may have unreal expectations. One inch groups from a stock Ruger .270 without working up a load are better that I'd expect.
The one thing that needs to be considered before letting a gunsmith pillar bed or epoxy bed that rifle is he may makes things worse. It's not always a panacea.
I had the same problem when I began reloading for the .223. I found that my RCBS dies were contacting the bullet at the very tip instead of the ogive. I ran a drill into the seating stem for a very short distance.
Then I noticed that the altered stem was marring the ogive where it contacted it...
Never crimped a round loaded for semi-auto rifles and have fired several thousands in competition.
I see no reason to crimp any rifle round except those fired in guns with tubular magazines. I have a Lee Crimp die in .375 H&H gathering dust.
The longer I reload, the less sense I see in having multiple loads for each caliber. Since I prefer complete penetration, I go with a heavy for caliber bullet like the 180gr Partition in .30-06 and use it on everything. Works well on elk, but doesn't destroy too much meat on whitetails.
I will...
My 7mm WSM requires that I set my dies to cam over. Anything less and I have cases that will not chamber.
FWIW, the guys on ShortMags.Org recommend against neck sizing because of the difficult chambering issue.
To be able to measure land-to-ogive distance with both precision and repetition, you will need special gauges like those made by Stoney Point. This is necessary because the land-to-ogive distance will change with different bullet shapes even when seated to the same depth. Actual bullet length...