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Rifles, Reloading, Optics, Equipment
Reloading
Neck diameter clearance on tight neck chamber
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<blockquote data-quote="DUSTY NOGGIN" data-source="post: 1837815" data-attributes="member: 89550"><p>you have a 308 necked 7mm rm chamber (( have you measured ?? ))</p><p></p><p>first things first , id measure to see exactly what your chamber measures -</p><p></p><p>but to assume you have and have determined the neck inner diameter to be .308</p><p></p><p></p><p>magman caught the 28 caliber</p><p></p><p>if you gave that chamber .003 clearance .. leaves you with .305 left</p><p>305 - 284 = .021 divided by 2 + .0105 -- ( .303-304 bushing )</p><p></p><p>if you gave that chamber .001 clearance .. leaves you with .307 left</p><p>307 - 284 = .0213 divided by 2 + .0115 -- ( .305-306 bushing )</p><p></p><p>.0105 is a very thin neck !! but so is .0115</p><p></p><p>i would carefully inspect the once fired cases for a slight radius in the neck to shoulder junction... as that will be your area that will give a little leaway . when you make your cut you will want aas big of a transition angle from thick brass to the thin brass as you can get ( that radius is your as big as you can get measurement) , too sharp of a cut at the end of your turn can create a breaking/ shear point when the case expands to seal at the chamber ( that small radius in the corner will give you that )</p><p></p><p>safety aspect of owing that rifle ... id find a way to label, stamp, engrave ... ect. "TIGHT NECK ONLY" in that gun ... not for you but for the ones who dont know ( enter what if's here )</p></blockquote><p></p>
[QUOTE="DUSTY NOGGIN, post: 1837815, member: 89550"] you have a 308 necked 7mm rm chamber (( have you measured ?? )) first things first , id measure to see exactly what your chamber measures - but to assume you have and have determined the neck inner diameter to be .308 magman caught the 28 caliber if you gave that chamber .003 clearance .. leaves you with .305 left 305 - 284 = .021 divided by 2 + .0105 -- ( .303-304 bushing ) if you gave that chamber .001 clearance .. leaves you with .307 left 307 - 284 = .0213 divided by 2 + .0115 -- ( .305-306 bushing ) .0105 is a very thin neck !! but so is .0115 i would carefully inspect the once fired cases for a slight radius in the neck to shoulder junction... as that will be your area that will give a little leaway . when you make your cut you will want aas big of a transition angle from thick brass to the thin brass as you can get ( that radius is your as big as you can get measurement) , too sharp of a cut at the end of your turn can create a breaking/ shear point when the case expands to seal at the chamber ( that small radius in the corner will give you that ) safety aspect of owing that rifle ... id find a way to label, stamp, engrave ... ect. "TIGHT NECK ONLY" in that gun ... not for you but for the ones who dont know ( enter what if's here ) [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Neck diameter clearance on tight neck chamber
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