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Rifles, Reloading, Optics, Equipment
Gunsmithing
338 edge 30 or 40 deg.?
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<blockquote data-quote="J E Custom" data-source="post: 424104" data-attributes="member: 2736"><p>If you read PO Ackleys Books you start to understand why he went to 40o shoulders.</p><p></p><p>Back when he was doing all of his experiments he did not have all of the wonderful cases</p><p>we have today and he was attempting to up the velocity in each case without going to</p><p>a larger case or action.</p><p></p><p>He discovered that 40o's was an absolute MAX and that any more gave you to many </p><p>problems and no gain in total performance.</p><p></p><p>Ackley himself agrees that somewhere arround 35o is optimal and all you gain is volume</p><p>(But not much).</p><p></p><p>Dave Kiff is correct and 35o to 37.5 is all one needs. And with today's larger cases even </p><p>that is not nessary except when shooting the largest bullets, a little more case capacity</p><p>will allow the use of a slower powder.</p><p></p><p>So depending on the use of a rifle the shoulder angle's will vary (Some of the old dangerous</p><p>game rifles had shoulder angles as low as 7o to 12o for ease of feeding and extraction) </p><p></p><p>The Newer cases start at 25o and go up and most are arround 30o.</p><p></p><p>Brass seams to hold up well at 35o. But at 40o fire forming can be problematic at times.</p><p></p><p>So my recommendations would be to stay with the 30o shoulder. Unless you are willing to </p><p>deal with the extra work of a steeper shoulder angle and the cost to gain some velocity.</p><p></p><p>If you want a wild cat then go with 35o to 37.5 if not stay with the 30o shoulder.</p><p></p><p>Just my opinion</p><p></p><p>J E CUSTOM</p></blockquote><p></p>
[QUOTE="J E Custom, post: 424104, member: 2736"] If you read PO Ackleys Books you start to understand why he went to 40o shoulders. Back when he was doing all of his experiments he did not have all of the wonderful cases we have today and he was attempting to up the velocity in each case without going to a larger case or action. He discovered that 40o's was an absolute MAX and that any more gave you to many problems and no gain in total performance. Ackley himself agrees that somewhere arround 35o is optimal and all you gain is volume (But not much). Dave Kiff is correct and 35o to 37.5 is all one needs. And with today's larger cases even that is not nessary except when shooting the largest bullets, a little more case capacity will allow the use of a slower powder. So depending on the use of a rifle the shoulder angle's will vary (Some of the old dangerous game rifles had shoulder angles as low as 7o to 12o for ease of feeding and extraction) The Newer cases start at 25o and go up and most are arround 30o. Brass seams to hold up well at 35o. But at 40o fire forming can be problematic at times. So my recommendations would be to stay with the 30o shoulder. Unless you are willing to deal with the extra work of a steeper shoulder angle and the cost to gain some velocity. If you want a wild cat then go with 35o to 37.5 if not stay with the 30o shoulder. Just my opinion J E CUSTOM [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Gunsmithing
338 edge 30 or 40 deg.?
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