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Rifles, Reloading, Optics, Equipment
Reloading
6.5x55 Ackley
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<blockquote data-quote="Trickymissfit" data-source="post: 778737" data-attributes="member: 25383"><p>I just didn't agree with Bob's notes. Some by experience, and others by simply looking at the loading data. The one that really surprised me was his 6mm data, and yet it had points that a lot folks won't pick up. Most load data in the manuals at max is not max in any way. The 6mm Remington is a 65K psi round, yet most loads you see are well under 57K psi, so that maybe where Bob was comming from. I have shot both the standard 6mm and the 6mmAI in the past, and I've found that the most you get with the Ackley is about 175fps, with one exception and that was maybe 215fps. The standard 6mm case is about it for the 24 cailber bore without going into overbore. The Ackley case takes it beyond that condition and into overbore unless you are talking about 100 grain and heavier bullets. Then there's a difference. Personally I've long felt that the ideal case for the 6mm would be the 6.5x55 necked down to 6mm, and blown out in the ackley configuration. But with a 1.65" shoulder length and a .33" neck length (or .35"). This round will sorta bridge the gap between the .243 and the 6mm; yet be like the 6/250AI on steroids. Better neck length is gonna help guide those 107 grain bullets, and I honestly think it's gonna produce close to 3200fps with the 107 grain Sierra bullet. A fireformed case ought to drop right in with a .330" neck length after shrinkage.</p><p> </p><p>I did find out that I had some other .257 RBT's +P data in a Speer manual, but it's almost identical to what AA published. But Bob is right in that the Ackley 257 is good for maybe another 200fps on a good day although AA claims about 300fps difference with a 117 grain bullet</p><p> </p><p>To further touch base on the improved 250 Savage case design. I shoot that case necked down to 6mm, and it is one efficient little case! It will push a 105 grain Amax to 3000fps without excessive pressures (still pretty hot). Needs a longer neck for the longer bullets. I don't use 250 Savage cases, but use generic .243 cases. I tried necking up 22-250 brass, and fireforming it, but case shrinkage was excessive! Looking at a reloading manual oneday I noticed the shoulder deninsions and angles of the .243 case verses the </p><p>22-250 case.Using the .243 case instead of the 22-250 displaced a lot less brass. Thus far less shrinkage (about 40% less). I shoot the standard 22-250 a lot. I've long felt that the case was getting very close to overbore, but still acceptable. Looks to me like the gains made with the 22-250 AI are minimal unless you are lucky enough to have a 1:9 twist Savage barrel. Then you could make use of the extra powder capacity. By the way that 250 improved case has gone from 20 caliber to at least 30 caliber over the years. I'd like to think that a .300 Savage case necked down to .257, and run thru a .250 Savage die might be a better combo. Cut the necks back to about .33" after fireforming.</p><p>gary</p></blockquote><p></p>
[QUOTE="Trickymissfit, post: 778737, member: 25383"] I just didn't agree with Bob's notes. Some by experience, and others by simply looking at the loading data. The one that really surprised me was his 6mm data, and yet it had points that a lot folks won't pick up. Most load data in the manuals at max is not max in any way. The 6mm Remington is a 65K psi round, yet most loads you see are well under 57K psi, so that maybe where Bob was comming from. I have shot both the standard 6mm and the 6mmAI in the past, and I've found that the most you get with the Ackley is about 175fps, with one exception and that was maybe 215fps. The standard 6mm case is about it for the 24 cailber bore without going into overbore. The Ackley case takes it beyond that condition and into overbore unless you are talking about 100 grain and heavier bullets. Then there's a difference. Personally I've long felt that the ideal case for the 6mm would be the 6.5x55 necked down to 6mm, and blown out in the ackley configuration. But with a 1.65" shoulder length and a .33" neck length (or .35"). This round will sorta bridge the gap between the .243 and the 6mm; yet be like the 6/250AI on steroids. Better neck length is gonna help guide those 107 grain bullets, and I honestly think it's gonna produce close to 3200fps with the 107 grain Sierra bullet. A fireformed case ought to drop right in with a .330" neck length after shrinkage. I did find out that I had some other .257 RBT's +P data in a Speer manual, but it's almost identical to what AA published. But Bob is right in that the Ackley 257 is good for maybe another 200fps on a good day although AA claims about 300fps difference with a 117 grain bullet To further touch base on the improved 250 Savage case design. I shoot that case necked down to 6mm, and it is one efficient little case! It will push a 105 grain Amax to 3000fps without excessive pressures (still pretty hot). Needs a longer neck for the longer bullets. I don't use 250 Savage cases, but use generic .243 cases. I tried necking up 22-250 brass, and fireforming it, but case shrinkage was excessive! Looking at a reloading manual oneday I noticed the shoulder deninsions and angles of the .243 case verses the 22-250 case.Using the .243 case instead of the 22-250 displaced a lot less brass. Thus far less shrinkage (about 40% less). I shoot the standard 22-250 a lot. I've long felt that the case was getting very close to overbore, but still acceptable. Looks to me like the gains made with the 22-250 AI are minimal unless you are lucky enough to have a 1:9 twist Savage barrel. Then you could make use of the extra powder capacity. By the way that 250 improved case has gone from 20 caliber to at least 30 caliber over the years. I'd like to think that a .300 Savage case necked down to .257, and run thru a .250 Savage die might be a better combo. Cut the necks back to about .33" after fireforming. gary [/QUOTE]
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6.5x55 Ackley
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