Neck tension and accuracy

98cwitr · May 18, 2026

Well, FML .342 is still too loose. Ordered a .338 now. Brass must be springing back. Ill get these annealed ASAP

WTNUT · May 24, 2026

98cwitr said:
Still working on load dev, and found a sweet spot for the CBTO at 2.860" (300wsm). However, I realized I was putting WAY too much neck tension on the cases. Outer diameter loaded is 0.345", and I was using a Redding .335 neck bushing (standard for 308win), which even resulted in .332 actual sized outer diameter. No wonder it was shaving copper off the bullets.

I've now ordered a .342" bushing in hope it will shore up some cold bore fliers and weird grouping behavior.

Anyone found that playing with solely the neck tension affected their accuracy a great deal?

Yes, on every rifle I own. I will add it changes from rifle to rifle depending on brass and the rifle. Some like 5/1000s some like 2/1000s and some in between. Neck tension is the last tweak in my load development.

Neck tension and accuracy

98cwitr

Well-Known Member

WTNUT

Well-Known Member

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