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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
LUCKY.....GROUP......CLUB ( BI - PODS - ..ONLY )
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<blockquote data-quote="Cybra" data-source="post: 24878" data-attributes="member: 936"><p>Sr90</p><p></p><p>Varget is a good powder choice. So is H380; I have tested them both in .308s and in a 7-08 Rem, and a couple other cartridges. One thing I have noticed, and this is dependent on seating depth, is primers. Try different ones. Believe it or not, but I get some of my best accuracy from LR Winchesters, particularly when using some rather unusal "reduced loads" of faster powders. I have also had good success with ball powders using those primers. I would advise you to seat into the rifling. In fact, seat your bullets a little long, and chamber a few, letting the rifling push them back into place upon bolt closure. Most people shy away from this approach for hunting ammo/tactical, for obvious reasons; but, for benchwork, it can be useful; once you determine the length the rounds end up at, back that figure off perhaps .002"-.005", and give it a try--they will chamber and eject smoothly, without hanging in the lands. If you're not using a single shot, then you either need a.) a hefy amount of neck tension, or b.) increase the distance back to .010" or more. It will probably increase your pressure anywhere from 4000-8000 psi, depending on all kinds of fun things, like jacket/core hardness, bearing surface length, bullet runout, etc, etc, BUT the one nice thing is it often reduces variations in bullet movement prior to primary ignition. It will also help alignment, assuming you're not using cases that are bent like a limp...noodle. Case prep is everything; if you're getting velocity variations YOU think are unacceptable, but the accuracy is there, the first things I'd do would be a.) seat bullets to the lands, and ticker minutely with the load for a few grain-variations, or a.2.) a change of primers. Crazy stuff, for sure; hence the addiction, I guess. <img src="http://images/icons/rolleyes.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> Primers, I suppose, would be my top guess, but you may find, once the bullet is seated to contact the lands, that the variations go away. I had a .257 Wby I rechambered to rid myself of the freebore. Before cutting her back, I could only get a 120gr flatbase to within .011" of the lands, and got average swings in Vel. of about 35fps. Afterwards, I got the little bugger down to around 10fps, which made me a whole lot happier--the rifle seemed pleased, also. <img src="http://images/icons/grin.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> </p><p></p><p>S1 You're going to have to write a book on this torque reduction theorism; seriously, now. I would buy it. I love all those technical write-ups. Hell of it is, there isn't enough out there!! Clear up one cob-web for me; was the break designed primarily to aid in bi-pod shooting, or is its effects documented off of a solid, bench-style rest as well?</p></blockquote><p></p>
[QUOTE="Cybra, post: 24878, member: 936"] Sr90 Varget is a good powder choice. So is H380; I have tested them both in .308s and in a 7-08 Rem, and a couple other cartridges. One thing I have noticed, and this is dependent on seating depth, is primers. Try different ones. Believe it or not, but I get some of my best accuracy from LR Winchesters, particularly when using some rather unusal "reduced loads" of faster powders. I have also had good success with ball powders using those primers. I would advise you to seat into the rifling. In fact, seat your bullets a little long, and chamber a few, letting the rifling push them back into place upon bolt closure. Most people shy away from this approach for hunting ammo/tactical, for obvious reasons; but, for benchwork, it can be useful; once you determine the length the rounds end up at, back that figure off perhaps .002"-.005", and give it a try--they will chamber and eject smoothly, without hanging in the lands. If you're not using a single shot, then you either need a.) a hefy amount of neck tension, or b.) increase the distance back to .010" or more. It will probably increase your pressure anywhere from 4000-8000 psi, depending on all kinds of fun things, like jacket/core hardness, bearing surface length, bullet runout, etc, etc, BUT the one nice thing is it often reduces variations in bullet movement prior to primary ignition. It will also help alignment, assuming you're not using cases that are bent like a limp...noodle. Case prep is everything; if you're getting velocity variations YOU think are unacceptable, but the accuracy is there, the first things I'd do would be a.) seat bullets to the lands, and ticker minutely with the load for a few grain-variations, or a.2.) a change of primers. Crazy stuff, for sure; hence the addiction, I guess. [img]images/icons/rolleyes.gif[/img] Primers, I suppose, would be my top guess, but you may find, once the bullet is seated to contact the lands, that the variations go away. I had a .257 Wby I rechambered to rid myself of the freebore. Before cutting her back, I could only get a 120gr flatbase to within .011" of the lands, and got average swings in Vel. of about 35fps. Afterwards, I got the little bugger down to around 10fps, which made me a whole lot happier--the rifle seemed pleased, also. [img]images/icons/grin.gif[/img] S1 You're going to have to write a book on this torque reduction theorism; seriously, now. I would buy it. I love all those technical write-ups. Hell of it is, there isn't enough out there!! Clear up one cob-web for me; was the break designed primarily to aid in bi-pod shooting, or is its effects documented off of a solid, bench-style rest as well? [/QUOTE]
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