After 55 years of reloading and shooting, I confess to being no expert...or dummy...but do admit to being lucky on a few occasions. The following are my own observations using "primerless/powderless" cartridges in my rifles. My notes will, hopefully, give some of my fellow novices something to ponder upon and perfect.
Have noticed, with something of a smile, all the refs on this and other forums re the subjects of seated bullet concentricity and seating depth...mutually exclusive and mutually inclusive subjects, whot?
For the "Newbie", like me, first of all satisfy yourself on these matters....absolutely determine, whatever it takes, the indicated runout of your bullets as they come out of the box,, but polished,) the indicated runout of your case necks as they come out of the neck-body sizer and, finally, the loaded bullet runout as measured at a consistent point on the neck and at some consistent position on the curve,ogive) of a nominal loaded, but primer-less, and powder-less bullet.
Record all measurements you can make up to this point.
Be astute enough to perform the above measurements when your barrel and chamber are new...it won't get any better than this! If your barrel has had quite a few rounds through it...all bets are off. Why?....because some of the lands will erode more or less than the others.....You did record the longest and shortest, and the widest and narrowest land scuffs, didn't you????
So, then....Joe Blow says for his cartridge, just like yours, he greases flies on his target at 200 meters with vv.v grains of www powder with bullets XXX seated at .YYY inches with scuff .ZZZ?
So, you make up a powderless, primerless round per Joe's parameters, chamber the round, close the bolt, open the bolt, extract the round and start measuring the rifling scuff on your polished bullet with your OptiVisors on your head and your best digital calipers in hand.
Huh?....What the Hey, Over?...Is Joe measuring from a new barrel or giving me the longest, shortest, or average scuff from the lands on his polished bullet ogive?....Trust me, or try it yourself, there can easily be .020 difference depending on which land-scuff you and/or he measure, especially when you get down to the scuff measurements on the more deeply,into the neck) seated bullet. That .020" difference can amount to quite a bit of pressure difference in a fired round. Wisht Joe had mentioned if his barrel was new or not.
If you are working from a barrel with a "few" rounds through it, you will note that as you seat the bullet deeper into the case,while also recording the bullet run-out associated with each seating), you will reach a point where,with your magnifying glass) you will see that chambering the dummy cartridge results in scuffs on the polished bullet from only 1 or more lands, but not all. Mark the beginning and end of such scuffs with a felt tip marker and put the cartridge on your run-out guage and note where the beginning and ending of the maximum and minimum of the run-out begins and ends. When you get down to the fine hairs,...with a "lightly" seated bullet... what you will likely be measuring will be the run-out of the bullet, as originally seated.
Soooo....want to correct any neck-sizing/bullet-seating abnormalities/un-concentricities by seating your bullets long so as to get them going down the barrel straight without distortion?.....err, ummm, you did measure just exactly where, from your breech, all the lands measured the same width on your polished bullets, didn't you???? And just what was the resulting velocity, ES, SD and agg of those groups?
BTW: Heaven forbid!!!... rather than see "the rifling straighten" a crookedy bullet, have even seen an "un-crookedy" bullet sometimes get more crookedy after chambering.....this from an otherwise perfect 6BRX chamber which will spit out shell after shell which will measure perfectly to spec.
Oops! Just what are the +/- tolerances on that spec?? Oh, you say you use Military Spec 105 D?....was that with a sample size of 200 and an AQL 4.0 or AQL 2.5? Hmmmm. Unless the AQL on all those pieces/parts is 0.0, don't you just graze the surface of the Moon with your landing module, kick up a little dust and go flying on past the Moon into Eternity instead of landing on Moon????
Is this a Great sport or what?
Have noticed, with something of a smile, all the refs on this and other forums re the subjects of seated bullet concentricity and seating depth...mutually exclusive and mutually inclusive subjects, whot?
For the "Newbie", like me, first of all satisfy yourself on these matters....absolutely determine, whatever it takes, the indicated runout of your bullets as they come out of the box,, but polished,) the indicated runout of your case necks as they come out of the neck-body sizer and, finally, the loaded bullet runout as measured at a consistent point on the neck and at some consistent position on the curve,ogive) of a nominal loaded, but primer-less, and powder-less bullet.
Record all measurements you can make up to this point.
Be astute enough to perform the above measurements when your barrel and chamber are new...it won't get any better than this! If your barrel has had quite a few rounds through it...all bets are off. Why?....because some of the lands will erode more or less than the others.....You did record the longest and shortest, and the widest and narrowest land scuffs, didn't you????
So, then....Joe Blow says for his cartridge, just like yours, he greases flies on his target at 200 meters with vv.v grains of www powder with bullets XXX seated at .YYY inches with scuff .ZZZ?
So, you make up a powderless, primerless round per Joe's parameters, chamber the round, close the bolt, open the bolt, extract the round and start measuring the rifling scuff on your polished bullet with your OptiVisors on your head and your best digital calipers in hand.
Huh?....What the Hey, Over?...Is Joe measuring from a new barrel or giving me the longest, shortest, or average scuff from the lands on his polished bullet ogive?....Trust me, or try it yourself, there can easily be .020 difference depending on which land-scuff you and/or he measure, especially when you get down to the scuff measurements on the more deeply,into the neck) seated bullet. That .020" difference can amount to quite a bit of pressure difference in a fired round. Wisht Joe had mentioned if his barrel was new or not.
If you are working from a barrel with a "few" rounds through it, you will note that as you seat the bullet deeper into the case,while also recording the bullet run-out associated with each seating), you will reach a point where,with your magnifying glass) you will see that chambering the dummy cartridge results in scuffs on the polished bullet from only 1 or more lands, but not all. Mark the beginning and end of such scuffs with a felt tip marker and put the cartridge on your run-out guage and note where the beginning and ending of the maximum and minimum of the run-out begins and ends. When you get down to the fine hairs,...with a "lightly" seated bullet... what you will likely be measuring will be the run-out of the bullet, as originally seated.
Soooo....want to correct any neck-sizing/bullet-seating abnormalities/un-concentricities by seating your bullets long so as to get them going down the barrel straight without distortion?.....err, ummm, you did measure just exactly where, from your breech, all the lands measured the same width on your polished bullets, didn't you???? And just what was the resulting velocity, ES, SD and agg of those groups?
BTW: Heaven forbid!!!... rather than see "the rifling straighten" a crookedy bullet, have even seen an "un-crookedy" bullet sometimes get more crookedy after chambering.....this from an otherwise perfect 6BRX chamber which will spit out shell after shell which will measure perfectly to spec.
Oops! Just what are the +/- tolerances on that spec?? Oh, you say you use Military Spec 105 D?....was that with a sample size of 200 and an AQL 4.0 or AQL 2.5? Hmmmm. Unless the AQL on all those pieces/parts is 0.0, don't you just graze the surface of the Moon with your landing module, kick up a little dust and go flying on past the Moon into Eternity instead of landing on Moon????
Is this a Great sport or what?
