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Rifles, Reloading, Optics, Equipment
Reloading
"Jamming" bullet into the lands?
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<blockquote data-quote="BountyHunter" data-source="post: 448200" data-attributes="member: 12"><p>You need to define the discussion a little more.</p><p> </p><p>"Jamming into the lands" is commonly referred to soft seating with minimal neck tension and letting the bullet seat itself into the lands and still withdraw. That is what is formally defined as "the jam" by Tony Boyer in his book. Mike Ratigan in his BR booke defines it similar except he wants not visible marks on the bullet while looked at with a magnifying loop. </p><p> </p><p>That is also done with the bolt stripped and firing pin removed.</p><p> </p><p>That normally measures out as far as .050-.070 from the start of the lands.</p><p> </p><p>That is the two most common ways to define jam and seating depths from the jam by BR shooters.</p><p> </p><p>It is interesting to note that those two are probably the two best SR BR shooters today and both use a lot of neck tension. Most LR BR shooters are using a minimum of .0015 to .003 as the norm also.</p><p> </p><p> "Seating into the lands from the start" can be anywhere from .005 to .040 into the lands as the norm. Normally that is done with enough neck tension and that you will not pull a bullet out. Final step of load tuning is normally neck tension over the .001 some use to as high as .004. Yes that can be used very successfully by LR shooters shooting single shot and with the right neck tension tuned load.</p><p> </p><p>Key in all of this is an accurate measurement from the "start of the lands" ie, touching. </p><p> </p><p>Soft seating a bullet in a case then measuring from that is normally a minimum of .040 into the lands to start and then if you go another .020 and only .001 neck tension, you will leave a bullet in the neck. </p><p> </p><p>Big fallacy that it will produce a pressure spike always. Many pressure tests report the opposite as it is more air space in the case. Plus it depends on the powder as to what type of pressure spike it gives as a norm.</p><p> </p><p>Yes it will it you use a max load with it way off and then jam into the lands. But then that goes against common sense reloading.</p><p> </p><p>However, if you are going to run singleshot, start into the lands and work your way off. you will never be wrong.</p><p> </p><p>If going to run a magazine, start a max magazine COAL and work back.</p><p> </p><p>Bergers guidelines for jumps from in to .020, then .040, .080 and .120 off to find a sweet spot (and then narrow down) make good sense. </p><p> </p><p>You will burn the barrel out moving .001-.005 at a time initially for most people.</p><p> </p><p>Neck tension is important in load tuning for KLR hunting and if you are seating bullets where they can be pushed back in by hand, you are asking for trouble IMO. You should be running at least .0015 to .003 tension depending on what your load likes.</p><p> </p><p>Now that fine tuning calls for neck bushings and annealing or you are just fooling yourself that you are controlling neck tension.</p><p> </p><p>BH</p></blockquote><p></p>
[QUOTE="BountyHunter, post: 448200, member: 12"] You need to define the discussion a little more. "Jamming into the lands" is commonly referred to soft seating with minimal neck tension and letting the bullet seat itself into the lands and still withdraw. That is what is formally defined as "the jam" by Tony Boyer in his book. Mike Ratigan in his BR booke defines it similar except he wants not visible marks on the bullet while looked at with a magnifying loop. That is also done with the bolt stripped and firing pin removed. That normally measures out as far as .050-.070 from the start of the lands. That is the two most common ways to define jam and seating depths from the jam by BR shooters. It is interesting to note that those two are probably the two best SR BR shooters today and both use a lot of neck tension. Most LR BR shooters are using a minimum of .0015 to .003 as the norm also. "Seating into the lands from the start" can be anywhere from .005 to .040 into the lands as the norm. Normally that is done with enough neck tension and that you will not pull a bullet out. Final step of load tuning is normally neck tension over the .001 some use to as high as .004. Yes that can be used very successfully by LR shooters shooting single shot and with the right neck tension tuned load. Key in all of this is an accurate measurement from the "start of the lands" ie, touching. Soft seating a bullet in a case then measuring from that is normally a minimum of .040 into the lands to start and then if you go another .020 and only .001 neck tension, you will leave a bullet in the neck. Big fallacy that it will produce a pressure spike always. Many pressure tests report the opposite as it is more air space in the case. Plus it depends on the powder as to what type of pressure spike it gives as a norm. Yes it will it you use a max load with it way off and then jam into the lands. But then that goes against common sense reloading. However, if you are going to run singleshot, start into the lands and work your way off. you will never be wrong. If going to run a magazine, start a max magazine COAL and work back. Bergers guidelines for jumps from in to .020, then .040, .080 and .120 off to find a sweet spot (and then narrow down) make good sense. You will burn the barrel out moving .001-.005 at a time initially for most people. Neck tension is important in load tuning for KLR hunting and if you are seating bullets where they can be pushed back in by hand, you are asking for trouble IMO. You should be running at least .0015 to .003 tension depending on what your load likes. Now that fine tuning calls for neck bushings and annealing or you are just fooling yourself that you are controlling neck tension. BH [/QUOTE]
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"Jamming" bullet into the lands?
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