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Long Range Hunting & Shooting
300 yard range(WIND) test with 257 AM
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<blockquote data-quote="Fiftydriver" data-source="post: 83610" data-attributes="member: 10"><p>TommyB,</p><p></p><p>Dan is getting me barrels on average 8 weeks after ordering them. He has supprised me with a few as soon as 6 weeks after order but that is not the norm. IT is pretty consistant with the 8-9 week shipping time.</p><p></p><p>Yes there is a 7mm Rem Mag improved. I believe it is called the 7mm Mach IV. There is an entire family on this case design including the 6mm, 6.5 and 7mm. There may be others, these are the three I am familiar with.</p><p></p><p>TO be honest, my recommendation would be against this round. The reason, and this is from an accuracy minded gunsmith so take it for that please, is that the current production belted magnum brass is relatively inconsistant in the headspace measurement, that being from the base to the forward edge of the rim. </p><p></p><p>Now we all know that a belted magnum headspaces off the shoulder once fired in the chamber which is as it should be but with my rifles, I chamber the barrels very tight. Doing this with a belted magnum round can result in a certain percentage of brass not fitting the chamber because their headspace dimensions are out of spec, often by a fair margin.</p><p></p><p>TO get around this problem, you chamber deeper then I like to because this headspace measurement will not conform to the chamber when fired, it will always be this way as the belt is part of the solid case head.</p><p></p><p>Now, non belted brass is the same way, in fact it generally has a wider variation in headspace BUT... The soft thin shoulder WILL conform under fireforming pressure. What this means is that the first time you fire the case it may be a tight fit chambering but after that it will drop in perfectly because it can conform to the chamber specs.</p><p></p><p>I do not know if this would interest you but I just drew up a reamer print and submitted it for a custom dimensioned 7mm Dakota reamer. It is throated to take advantage of the Rem 700 receiver length.</p><p></p><p>This in my opinion would be a vastly superior choice over the 7mm Mach IV. The 7mm Dakota will match the 7mm STW in same length barrels and do so with a case length no longer then the standard 7mm Rem Mag. It also gets rid of the belt and all the problems associated with it.</p><p></p><p>The brass is more expensive but starting late this fall and winter, Norma will be making Dakota brass for them, at least that is the rumor going around.</p><p></p><p>Other advantages of this round, no fireforming needed, standard dies instead of having custom dies built, much higher performance then any 7mm Rem Mag based wildcat and I will have the reamer here in a couple months so that would not cost you extra either.</p><p></p><p>In a lightweight rifle it is alot of power but with a Holland QD brake it would be a ***** cat to shoot. The lighter the rifle, the better the brakes work.</p><p></p><p>Just another idea to muddy the waters a bit more /ubbthreads/images/graemlins/grin.gif!!</p><p></p><p>Kirby Allen(50)</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 83610, member: 10"] TommyB, Dan is getting me barrels on average 8 weeks after ordering them. He has supprised me with a few as soon as 6 weeks after order but that is not the norm. IT is pretty consistant with the 8-9 week shipping time. Yes there is a 7mm Rem Mag improved. I believe it is called the 7mm Mach IV. There is an entire family on this case design including the 6mm, 6.5 and 7mm. There may be others, these are the three I am familiar with. TO be honest, my recommendation would be against this round. The reason, and this is from an accuracy minded gunsmith so take it for that please, is that the current production belted magnum brass is relatively inconsistant in the headspace measurement, that being from the base to the forward edge of the rim. Now we all know that a belted magnum headspaces off the shoulder once fired in the chamber which is as it should be but with my rifles, I chamber the barrels very tight. Doing this with a belted magnum round can result in a certain percentage of brass not fitting the chamber because their headspace dimensions are out of spec, often by a fair margin. TO get around this problem, you chamber deeper then I like to because this headspace measurement will not conform to the chamber when fired, it will always be this way as the belt is part of the solid case head. Now, non belted brass is the same way, in fact it generally has a wider variation in headspace BUT... The soft thin shoulder WILL conform under fireforming pressure. What this means is that the first time you fire the case it may be a tight fit chambering but after that it will drop in perfectly because it can conform to the chamber specs. I do not know if this would interest you but I just drew up a reamer print and submitted it for a custom dimensioned 7mm Dakota reamer. It is throated to take advantage of the Rem 700 receiver length. This in my opinion would be a vastly superior choice over the 7mm Mach IV. The 7mm Dakota will match the 7mm STW in same length barrels and do so with a case length no longer then the standard 7mm Rem Mag. It also gets rid of the belt and all the problems associated with it. The brass is more expensive but starting late this fall and winter, Norma will be making Dakota brass for them, at least that is the rumor going around. Other advantages of this round, no fireforming needed, standard dies instead of having custom dies built, much higher performance then any 7mm Rem Mag based wildcat and I will have the reamer here in a couple months so that would not cost you extra either. In a lightweight rifle it is alot of power but with a Holland QD brake it would be a ***** cat to shoot. The lighter the rifle, the better the brakes work. Just another idea to muddy the waters a bit more [img]/ubbthreads/images/graemlins/grin.gif[/img]!! Kirby Allen(50) [/QUOTE]
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300 yard range(WIND) test with 257 AM
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