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Belted Vs Non Belted Cartridges

Belted Vs Non Belted Cartridges
« on: October 28, 2018, 06:15:30 AM »
I own a Weatherby 338-378 RC rifle that I purchased 2 years ago.  I had a gunsmith remount the scope and clean the bolt, barrel, etc.  He has won many awards at long range shooting competitions.  He told me that a belted cartridge is not as accurate as ones without a belt.  Is this true?  Is the 338-378 accurate out beyond 1000 or even 1500 yards?

Also, even though the 338-378 has a belt, is the headspace determined by the belt or the shoulders.  I only ask this as I have read conflicting reports on this question.

Thank you for any thoughts.

dubyam

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Re: Belted Vs Non Belted Cartridges
« Reply #1 on: October 28, 2018, 08:41:22 AM »
I hear this fairly frequently. My experience is that this entire idea is founded upon a potential minuscule difference, and relates far more to brass consistency than any other factor. What does this mean? It means that quality brass, in a carefully cut chamber, with or without a belt, is capable of excellent accuracy.  If everything is kept equal (which would be nearly impossible) a beltless round might have a very minuscule (think in terms of less than a tenth of a minute of angle) better accuracy potential, but even that is suspect. That the military has used and still uses the 300WinMag for sniper use confirms for me the idea is without much merit.

For all belted rounds, headspace occurs at the belt, technically. But that's for folks using factory ammo. For handloaders, we can adjust the sizing dies (using neck dies, shoulder bump dies, and FL size dies) to move the shoulder back .001-.002" from fired case measurements, creating a shoulder headspacing situation. At that point, in my specific rifle, with my specific handloads, headspacong occurs at the shoulder, not the belt.
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Re: Belted Vs Non Belted Cartridges
« Reply #2 on: October 29, 2018, 06:36:00 AM »
When I rebarreled my 270 and 340 Bees I had my Smith cut the belt -.002 since the brass manufacturers don't hold to SAAMI specs on the belted cartridge cases very well. I adjusted my sizing dies to headspace on the belt and the shoulder (took a few tries to achieve this). I know it's overkill but what the heck. GJ
« Last Edit: October 29, 2018, 06:40:38 AM by GrandeJuan »