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Rifles, Reloading, Optics, Equipment
Reloading
.375 H&H Fireform to .375 WBY?
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<blockquote data-quote="MagnumManiac" data-source="post: 900915" data-attributes="member: 10755"><p>As I stated, the testing that I did was with factory ammo! I was using Weatherby factory ammo, and my buddy was using Remingtom factory ammo, the difference between the 2 were 20-30 fps with 300gr pills.</p><p>And, yes, you are correct that the RUM case SHOULD produce higher and higher velocities with handloading, but my buddies rifle gets pressure signs well before I do. Even on my Pressure TraceII his rifle is running at max pressure with factory velocities, which I believe is due to the case capacity, or better put, the expansion ratio not being able to burn the powder efficiently enough to sustain the push for those higher velocities. A slower progessive powder is needed to get the full potential out of the RUM case in 375, I think the same is true of the 338 RUM to a lesser extent, maybe RL17 is the type of powder needed, but a slower version?</p><p>There is a point when adding more powder just doesn't increase velocity because the burning rate influences the peak pressure to rise too sharply and the bullet just doesn't accelerate as fast as the pressure rises, what was coined overbore is nothing more than the expansion ratio being too large for the powder to burn progressively for maximum bullet acceleration.</p><p></p><p>Longestrange,</p><p>The 375Weatherby actually has a longer neck than the H+H, but due to fireforming, the neck actually is pulled back and shortened when the rest of the case and shoulder are blown out to match the new chamber, with a few loads the brass grows back to proper length.</p><p>Also, the standard 375Weatherby chamber has 1/2" of freebore, which is what mine has and my rifle has not suffered in any way from this, it shoots one hole groups regularly and clover leafs the rest of the time. As long as you headspace off the shoulder after fire forming you will have good case life.</p><p>I seat my bullets to max mag length, in my case 3.610", with all bullet weights and it doesn't make any difference to accuracy if I juggle seating depths, so I just leave mine as is.</p><p></p><p>Cheers.</p><p>gun)</p></blockquote><p></p>
[QUOTE="MagnumManiac, post: 900915, member: 10755"] As I stated, the testing that I did was with factory ammo! I was using Weatherby factory ammo, and my buddy was using Remingtom factory ammo, the difference between the 2 were 20-30 fps with 300gr pills. And, yes, you are correct that the RUM case SHOULD produce higher and higher velocities with handloading, but my buddies rifle gets pressure signs well before I do. Even on my Pressure TraceII his rifle is running at max pressure with factory velocities, which I believe is due to the case capacity, or better put, the expansion ratio not being able to burn the powder efficiently enough to sustain the push for those higher velocities. A slower progessive powder is needed to get the full potential out of the RUM case in 375, I think the same is true of the 338 RUM to a lesser extent, maybe RL17 is the type of powder needed, but a slower version? There is a point when adding more powder just doesn't increase velocity because the burning rate influences the peak pressure to rise too sharply and the bullet just doesn't accelerate as fast as the pressure rises, what was coined overbore is nothing more than the expansion ratio being too large for the powder to burn progressively for maximum bullet acceleration. Longestrange, The 375Weatherby actually has a longer neck than the H+H, but due to fireforming, the neck actually is pulled back and shortened when the rest of the case and shoulder are blown out to match the new chamber, with a few loads the brass grows back to proper length. Also, the standard 375Weatherby chamber has 1/2" of freebore, which is what mine has and my rifle has not suffered in any way from this, it shoots one hole groups regularly and clover leafs the rest of the time. As long as you headspace off the shoulder after fire forming you will have good case life. I seat my bullets to max mag length, in my case 3.610", with all bullet weights and it doesn't make any difference to accuracy if I juggle seating depths, so I just leave mine as is. Cheers. gun) [/QUOTE]
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.375 H&H Fireform to .375 WBY?
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