Thread: Fire forming 270 to 280ai

Originally Posted by grandpamac

Greetings @Trav-6mmrem,
Don't worry about a donut forming as the .280 is longer to the base of the neck than the .270 which will prevent this.

Regards Grandpamac.

While shifting the original neck shoulder junction to the new shoulder might takeaway the initial risk ,should the shoulder brass be thicker than the original neck, steep shoulders have a higher propensity for donuts to form. Iv had them form after one firing in an early lot of nosler 280ai factory brass while latter batches have not. Iv also had to deal with them in factory norma 6.5x284 brass. While it isn't that common, its very easy to keep an eye so I would say ignore donuts at your peril. I have had success preventing it by neck turning with a 40 deg cutter and nipping a few thou into the shoulder.