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October 15, 2013, 05:49 PM | #26 | |
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One thing that IS important is that the bullet be precisely seated against the lands. T.J. Jackson reported this fact in the May 1987 issue of Precision Shooting. In a letter to the Editor, T.J. wrote, “...in all our testing in that Houston warehouse... and the dozens and dozens of groups that Virgil King shot in there ‘in the zeroes’... he NEVER fired a single official screamer group when he was ‘jumping’ bullets. All his best groups were always seated into the lands, or at the very least... touching the lands.” I can't help but think that what held "back then", ain't necessarily so today... VLD's, secant and hybrid ogives are more recent developments, are they not? I wasn't shooting back when this old research was done. Your personal experience?
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October 16, 2013, 04:55 PM | #27 |
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My experience is 99+% with Sierra bullets. I and most others feel they shoot most accurate gently pushed into the lands when chambered/fired.
Berger's VLD bullets seem to prefer a few thousandths jump to the lands as they explain in their web site. The difference is the angle the rifling makes with the bullet's ogives. Bergers are different than Sierras. Here's Berger's Brian Litz's Effects of Cartridge Over All Length (COAL ) and Cartridge Base To Ogive (CBTO ) on such stuff: http://www.bergerbullets.com/wp-cont...13/03/COAL.pdf One thing I don't see him mentioning is the bullet's ogive position relative to the bolt face or lands is determined by the shoulder on cases headspacing there. As virtually all such cases have a few thousandths inch spread in their head-to-shoulder length, that also will be present in the chamber when the round fires. The bullet's contact point on the ogive will have the same dimensional spread relative to the lands. As detailed and intelligent he is regarding all this stuff, I find it amazing he doesn't address this part of the equasion unless he thinks is not an issue. But its the only reference that gives accurate bullet jump to the lands measurements. |
October 17, 2013, 05:24 AM | #28 | |
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Bart B., why don't you try an experiment, neck size one case, and full length size another, then use a seating die to seat the same brand/make of bullet in each, to prove to yourself that the bullet ends up in the same position in each case. Jimro
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October 17, 2013, 10:31 AM | #29 |
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Seater die
I believe that all the full length sizing dies are about equal i.e. use what you like. The one die I think is worth buying is the Forster "Ultra micrometer seater die" I use them in 3 different calibers and have found the precision of adjustment excellent and repeatable. http://www.midwayusa.com/product/395...308-winchester
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October 17, 2013, 11:02 AM | #30 |
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Jimro,
What Bart's pointing out is that when you fire, the cartridge moves forward and stops against whatever surface it's headspacing on. That, in turn, determines how far the case neck and bullet move forward in the chamber and therefore how far the bullet is from the lands. So, theoretically, you want to know the distance of the bullet ogive from the headspacing surface, be it the shoulder, belt, rim or case mouth for greatest consistency. Most of the time, if your cases have the same load history, they are sized within a couple thousandths of being the same, and so the method of measuring from the base of the cartridge to the bullet ogive doesn't tend to introduce more error than that. The instances where I've seen that go awry were where a case head had a significant rim bend that survived resizing, and therefore cause a bullet to be seated deeper with respect to the headspace than was intended. Where a case used to gauge the ogive was a different length to its headspace stopping surface than the cases being fired. Where brass was growing either due to neck sizing or increased spring-back with work hardening. I suspect it is unusual for these errors to exceed a hundredth of an inch, but it's not impossible. I finally made a seating depth measuring tool that registers off the case shoulder for rimless bottleneck cases. It makes it quicker to set up a seating die and then serves as a go/no-go gauge on finished ammunition to final check for any loading process error that may hae caused an unexpected bullet position.
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October 17, 2013, 11:51 AM | #31 |
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Most shooter know the length to the ogives from the CBTO. If the head to shoulder length was a factor and I'm sure some may figure that in but in the accuracy game how important is that?
Reading this loading data Q: What’s your match load for the .300 WSM? Shiraz: I use Norma brass with turned necks. At the Berger SW Nationals I used Berger 215gr Hybrids, Fed 215 LR magnum primers, and a stout load of Hodgdon H4831 SC. This drives the 215s at around 2910 FPS. If that sounds fast, remember I’m using a a 32″-long barrel. Q: Can you tell us about your chamber and your fire-forming process? Shiraz: On the .300” WSM [I run] a tight-neck .336” chamber for turned necks. Basically, I fire-form all my brass in a fire-form barrel and save the good barrels for matches. Gordy is so good that he can chamber different barrels to within .0002” in the headspace dimension. That way I can have several same-caliber barrels and can use the same brass for all those barrels. I use a .0005″ shoulder bump for my brass. I load the bullets so that the bearing surface sits above the doughnut ring. Here is the full article http://bulletin.accurateshooter.com/...sm-f-open-rig/
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October 17, 2013, 12:13 PM | #32 | |
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Neck only sized fired cases, bullet seated in a sizer, loaded round headspace from head to shoulder datum; 1.631", case head to bullet ogive contact point from the seater, 2.600". Full length sized fired cases with a .003" shoudler setback, bullet seated in a sizer, loaded round headspace from head to shoulder datum; 1.628", case head to bullet ogive contact point from the seater, 2.600". I agree, both have the bullet the same distance forward of the case head. But one's shoulder is .003" closer to the bullet ogive contact point from the seater when fired. The loaded round with the full length sized case will position the bullet .003" further forward in the chamber than the neck only sized one. Both have their shoulder hard into the chamber shoulder when the primer fires. It's the head to shoulder difference that causes this. The full length sized case will also have its head .003" further away from the bolt face than the neck only sized one; head clearance for that round will be greater. With new rimmed and belted cases, their headspace point spread from the case head is no more than about .001" for a given lot of brass. Only when belted or rimmed cases are full length sized so they headspace on their shoulders does the above matter come into play as far as where the bullet rests in the chamber when fired. Otherwise, its the head to belt/rim front surface dimension spread that determines the spread in where the bullet is in the chamber. Unclenick, your tool's much fancier than the one I used to measure the same thing. I just wedged a dial indicator into a seating die for mine. Last edited by Bart B.; October 17, 2013 at 02:04 PM. |
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October 17, 2013, 02:59 PM | #33 |
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"IME, cheap dies are hard to adjust precisely and change adjustment quickly. Better dies have more adjustability. Also, I can't say for sure, but better dies IME are cut to build a slightly larger case. Cheaper dies are basically just machined to provide a safe, non-issue product for the maker."
If you mean mic head seaters seaters, say so. Otherwise that whole pasaage becomes pure mush. But they are all fully adjustable! You're assumption that others have no better skills at adjusting seaters than you is unwarranted . "When I say cheaper, I'm talking RCBS and Hornady basic sets. When I say better, I'm talking Forster dies with the ultra seater. Redding high end sets are a level beyond, but I don't like the process." Without a clue what you don't like about "Redding high end sets" being a level beyond" (what "sets", and "beyond" what?) but you don't like the "process" (what process?), this too is a meaningless mush that helps no one. To me, I want an FL die which will minimally change the outer case wall, bump the shoulder back and pull the neck id to the proper size. IME, this gives me good exterior case runout and good bullet runout. We would all like that! But chambers and dies (both sizers and seaters), including Forsters and Reddings, all have standard SAAMI manufactoring tolerances and NO maker has a lock on being making more 'precise' ammo than another. The specific dimensions we may get from any die set (sizer and/or seater) is pure luck of the draw, not the brand. Die makers all strive to stay within standard SAAMI tolerance points and anything inside that range is as 'precise/tight' as anything else. And which end of the tolerance range do you think manufactors should try for anyway? Anyone thinking we can predict how much accuracy improvement someone might expect from a costly die set just doesn't understand the way it all works. If the present set closely matches what's needed there will be little or no improvement with any other set. But, IF the present dies don't match the chamber, you might cut groups in half ... but that much is unlikely and you might actually do just as well with any other conventional set. Most likely it will be somewhere in the middle but none of us have a valid clue about that! The only thing we can say for sure is Redding/Forster comp seaters will always do a good, if not perfect, job (but no seater can make straight ammo from cases with bad necks)! Just buying more expensive reloading tools doesn't guarantee anything at all unless they are properly used and reloading skill doesn't come from a box of any color or price. Bottom line, if you have reason to believe your present dies are the limiting factor on your accuracy, try another set and hope for some degree of improvement but don't do it expecting to decrease group sizes by 5/8", etc. ?? Last edited by wncchester; October 17, 2013 at 03:23 PM. |
October 18, 2013, 08:26 AM | #34 | |
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There are no reloading tool standards in SAAMI specs I'm aware of; if there is, it's a well-kept secret. Reloading tool companies set their own specs based on their objectives. As consumers put the reloading tools together to do things with all sorts and varieties of components, nobody has any control over the results except the consumer. Companies that follow SAAMI specs do so voluntarily; no regulations require they comply. SAAMI has dimensional tolerances for cases, chambers, bullets, bore and groove dimensions. Barrel and ammo manufacturers set their own dimensions and tolerances for them. Same for people making chambering reamers. Last edited by Bart B.; October 18, 2013 at 08:40 AM. |
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October 18, 2013, 08:34 AM | #35 |
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I hate to say this but it's pretty simple if companies that made dies didn't follow SAAMI spec on their dies who would buy them.
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October 18, 2013, 08:52 AM | #36 |
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Old Roper, that's a good question.
What about this issue? 30 caliber bullets for the .308 Win. are SAAMI spec'd at .3090" - .0030"; they can be any diameter from .3070" to .3090". What diameter does the bullet chamber in seating dies have to be in order to follow a SAAMI spec? I've never measured one but my 30 caliber seaters have enough clearance in that chamber to easily let .3092" diameter bullets go in. To say nothing about the die's neck or body diameters that need to be smaller than those of the chamber else they won't size down fired cases. Last edited by Bart B.; October 18, 2013 at 12:23 PM. |
October 18, 2013, 07:03 PM | #37 | |
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October 18, 2013, 09:03 PM | #38 |
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Bart B, I don't do the what if's.
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October 19, 2013, 08:31 AM | #39 |
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Old Roper, I didn't ask a "what if" question.
SAAMI has no affiliation with nor voting, associate and supporting members manufacturing only reloading tools and they list no reloading tool standards or specs. Which of their chamber and/or cartridge specifications and standards do reloading tool manufacturers follow? |
October 19, 2013, 09:39 AM | #40 | |
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Once the brass has filled the chamber, the distance of the bearing surface to the lands is the same even if the headspace shoulder datum is off initially between two different cartridges, so the distance the bullet has to travel to engage the lands is the same in each case. If firing pin can shove the brass forward, and either there isn't enough pressure to cause the brass to fill the chamber, or the bullet leaves the brass before the cartridge has stretched to fill the chamber, then the distance from the bearing surface to the shoulder datum does matter. Based on what I know of modern high pressure ammo, I believe the first scenario is more likely, that the case has filled the chamber before the bullet significantly moves (the thinner brass towards the shoulder expands first, pushing the case head back against the bolt face) before the pressure can significantly overcome the inertia of the bullet and get it moving. I could definitely be wrong about this. Jimro
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October 19, 2013, 09:55 AM | #41 |
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You buy a set of dies ONCE.... Why cut corners. I buy only Redding bushing dies. You pay extra,but like I said-You buy dies once. Take care of them and they will out last you. You buy Match primers,Match Bullets,Match Brass and then assemble them them with cheap Dies???. WHY??
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October 19, 2013, 10:03 AM | #42 | |
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It does seem logical that the pressures needed to first unseat the primer, and then what we would assume to be even higher pressures needed to expand the case, would be greater than that needed to unseat the bullet and begin moving it forward. Seems to boil down to the pressure required to expand the case, being less than that required to unseat the bullet? Does the fact that the powder ignition first happens at the case head, and then moves forward as the powder burns have anything to do with it? This article doesn't really address it...anyone have the "facts"? http://www.hornady.com/ballistics-resource/internal
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October 19, 2013, 11:33 AM | #43 |
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In all my tests with different charge weights, those with about 10% below max in well polished .308 Win cases start coming out of the chamber with the primer pushed out past the case head. The more the charge is reduced, the more the primer's out past the case head. At about 15% below max, primer stuck out several thousandths of an inch and were easily seen that way.
Note those well polished cases showed total chamber markings on them all the way from shoulder to pressure ring with maximum loads. As loads were reduced, the case body in front of the pressure ring began staying smooth and shiny; no chamber finish marks on the case until further forward on the case body. Mild loads only had the front third or so of the case body marked with chamber irregularities. That's evidence to me the bullet leaves the case long before the case expands to fill the chamber as long as the bolt face is considered part of the chamber. |
October 19, 2013, 11:50 AM | #44 |
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Bart B, Here is your question
What about this issue? 30 caliber bullets for the .308 Win. are SAAMI spec'd at .3090" - .0030"; they can be any diameter from .3070" to .3090". What diameter does the bullet chamber in seating dies have to be in order to follow a SAAMI spec? I've never measured one but my 30 caliber seaters have enough clearance in that chamber to easily let .3092" diameter bullets go in. To say nothing about the die's neck or body diameters that need to be smaller than those of the chamber else they won't size down fired cases. _________________________________________________________________ Like I told you I don't do the what if's and not sure what your not understanding. In SAAMI spec drawing they show bullet dia .3090" -.0030" according to you that means can be anywhere from .3070" to .3090" dia. http://www.saami.org/specifications_...wnload/206.pdf Sure there no SAAMI spec member that just makes reloading tools but Hornady is a voting member and doesn't voting member own RCBS. I sure know the dia of my bullet seater.
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October 19, 2013, 03:45 PM | #45 |
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Roper, no way do I think 30 caliber bullet seaters' chamber diameter should be the same size as any 30 caliber bullet.
What I didn't understand was what SAAMI specs reloading tool companies choose to follow. Dimensions for the same part of SAAMI's drawings and its specs are different between chamber and cartridge ones. Surely sizing die dimensions have to be smaller than case dimensions else they would never size fired cases enough to fit in the smallest chamber. My interest was finding out what differences reloading dies were spec'd to, if there was an industry standard. For all I know brand A may well be different than brands B, C, D and E. ATK owns RCBS but I don't know if they pass on to RCBS any SAAMI specs and standards for reloading tools. Same thing for Hornady. Measured my seven bullet seaters for .308 Win., .30-.338 Win Mag and .300 Win Mag to get the bullet chamber diameters at the mouth juncture: Wilson BR chamber type .308, circa 1966; .3105" RCBS standard .308, circa 1966; . . . . . . .3100" RCBS standard .308, circa 1979; . . . . . . .3115" RCBS competition .308, circa 1980's; . . . .3107" RCBS standard .300 Win Mag, circa 1999, .3104" RCBS standard .30-.338, circa 1967, . . . .3102" Bonanza BR .30-.338, circa 1980; . . . . . .3093" Lapua D46 185-gr. FMJRB match bullets I shot were all .3092" diameter. They easily slid up into the Bonanza seater's bullet chamber. As Sierra's 30 caliber match bullets have been in the .3082" to .3084" range for decades, no 30 caliber commercial bullet seater I know of has a bullet chamber smaller. I know better to think a commercial seater's bullet chamber would be the same size as a bullet; half of them would probably stick in the seater chamber. At least I've never heard of one not letting a Sierra bullet slide easily into nor out of one. Last edited by Bart B.; October 19, 2013 at 03:52 PM. |
October 19, 2013, 05:33 PM | #46 | |
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But life is not perfect, the bananas I buy at grocery stores are straighter than the cases that come out of my Lee full length 30-06 sizing die. Since I found small base dies, all my 223, 308 and 30-06 cases are sized with Lyman or RCBS small base dies, and on good days, I will shoot sub MOA. I really like the Bonanza competition seating dies, that is the only "competition die" that I will pay extra for.
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October 19, 2013, 08:13 PM | #47 | |
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October 19, 2013, 09:38 PM | #48 | ||
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Never tried the other seaters, they look to be the same micrometer adjustment type, probably work fine. I like the micrometer seating dies, have paid more for them, but as for sizing dies, I have Redding dies and Bonanza match and can't say the ammo is any better for having gone through them.
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October 19, 2013, 10:51 PM | #49 | |
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October 20, 2013, 10:21 AM | #50 |
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I recently asked myself the same question. Over the years I've found that some Premium dies aren't worth the money and others are, depending on the task.
I recently rebarreled my rifle and the barrel maker cut the chamber to minimum SAAMI specs. This allows me to Full length size each and every case. The differences in sized and fired are very little so the brass isn't worked all that much. I also have cases that haven't had the shoulder creep out to the point I can't easily close the bolt. In Full length sizing dies, of which I have 4 for my caliber, I found that the Hornady Custom Grade New Dimension gave the best results. Even less case neck runout than the Forster Bench Rest F/L sizing die. When it comes to seating bullets nice and straight the honor goes to the Forster BR Seating die. The Hornady, even thought he sizing die was superior, was way down the list of "straightness". Of the four sets of dies I have I size with the Hornady (total cost for set ~$30) and seat with the Forster (cost for single die ~$40). When it comes to seating, Lee dies are OK but not quite as accurate as the Forster (bonanza design). Lee sizing dies also are OK but they are so roughly finished the sized brass looks like it's been scraped with sandpaper. The Hornady sizing die is a mirror finish inside and the cases look great.
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