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September 20, 2018, 05:37 PM | #1 |
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30-30 Win OFB excessive case stretch ?
I bought about 300 pcs of once fired 30-30 Win brass and i'm observing that I need to push the shoulders back approx .022" to get them to SAMMI spec ?? Is this common for lever guns to stretch the brass this much ? I'm loading 30-30 cowboy loads for my new production Henry 30-30.
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September 20, 2018, 06:18 PM | #2 |
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Not sure because I never measured before and after sizing. I just FL Resize and trim them all to uniform length for a consistent roll crimp. I don't worry about the shoulder because it's a rimmed cartridge in a lever action. I do carefully inspect the brass the same as any other rifle cartridge.
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September 20, 2018, 09:33 PM | #3 |
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If you're needing to "push" the shoulders back .022" to get them to SAMMI, how far would you need to "relocate" the shoulder back so that they measure .002" shorter than once fired brass from your own rifle?
Just wondering what your chamber does for your own once fired brass?.... Last edited by eschafer; September 22, 2018 at 09:10 PM. |
September 21, 2018, 05:41 AM | #4 | |
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"To be old an wise you must have been young and stupid" Last edited by Road_Clam; September 21, 2018 at 05:49 AM. |
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September 21, 2018, 06:59 AM | #5 |
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Determine what is most important--case life or functionality. Then proceed accordingly.
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September 21, 2018, 08:52 AM | #6 | |
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There is no manufacturer that sells cases to reloaders that know what they are doing; I do not want cases that will allow the bolt to close, I ant cases that will not allow the bolt to close. SO? When I start to size a case I am forced to reduce the length of the case from the shoulder to the head if the case (or as bumper say; bump the shoulder back), difference: I have to know when to quit sizing. .022" is a good number to start with. A variety of cases: Manufacturers do not manufacturer cases with a variety of case rim thickness. If they did I would prefer using the case with the thickest rim. I do not want my rimmed case heads moving. That brings us back to the full length sizing of cases for a chamber you do not have. Increasing the length of the case from the shoulder to the case head can off set the length of the chamber with the case. That does not change the design as in the 30/30 head spaces off of the rim and that leads me to believe they had little interest in what happened the case in front of the rim 'or belt'. The rim was designed to hold the case to the rear and the case body was designed to fill the chamber. F. Guffey |
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September 21, 2018, 09:01 AM | #7 | |
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F. Guffey |
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September 21, 2018, 09:14 AM | #8 | |
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I know; reloaders move the shoulder back when sizing and move the shoulder forward when firing. To me this proves reloaders do not have a clue. F. Guffey |
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September 21, 2018, 09:59 AM | #9 |
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"I am wondering why you are trying to size your cases for a chamber you do not have. Time and time again I have claimed my favorite cases are cases shot in trashy old chambers. I have purchased cases from firing ranges, one range would allow me to measure the length of the cases from the shoulder to the case head; again, I was only interested in cases that were ling from the shoulder to the case head. They charged me by the hundred but threw in an extra 10 for every hundred.
There is no manufacturer that sells cases to reloaders that know what they are doing; I do not want cases that will allow the bolt to close, I ant cases that will not allow the bolt to close. SO? When I start to size a case I am forced to reduce the length of the case from the shoulder to the head if the case (or as bumper say; bump the shoulder back), difference: I have to know when to quit sizing. .022" is a good number to start with. A variety of cases: Manufacturers do not manufacturer cases with a variety of case rim thickness. If they did I would prefer using the case with the thickest rim. I do not want my rimmed case heads moving. That brings us back to the full length sizing of cases for a chamber you do not have. Increasing the length of the case from the shoulder to the case head can off set the length of the chamber with the case. That does not change the design as in the 30/30 head spaces off of the rim and that leads me to believe they had little interest in what happened the case in front of the rim 'or belt'. The rim was designed to hold the case to the rear and the case body was designed to fill the chamber. F. Guffey" Mr. Guffey.... As you may know, I'm very new to all this (see my post count ) and trying to capture all I can from these threads, but above, in your 1st reply, are you suggesting that these cases he purchased may or may not be once fired cases, but they surely are not just stretched .022' but are rather cases that have been HAMMERED with heavy loads, and are best discarded and not used? To me, .022" of stretch seems excessive, if at all possible with a standard chamber?? Likewise with the original poster, just trying to get this all understood... Thank you in advance.. eschafer Last edited by eschafer; September 21, 2018 at 10:19 AM. |
September 21, 2018, 10:56 AM | #10 |
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Road Clam,
This is a common issue with both rimmed and belted cases because of cumulative tolerances in the combination of headspace and shoulder fit. The standards are set up so a manufacturer can make ammunition that will work in any gun chambered for 30-30. Because rimmed and belted cartridges are meant to seat on the rim headspace surface or the belt headspace surface in the chamber, they have to make sure the shoulder of the case does not reach the shoulder of the chamber even when the rim or belt tolerances are at their most extreme looseness in order to be relying on the gauged headspace surface and not on a randomly located shoulder. So, where rimless cartridge headspace determines both fit and excess shoulder space (excess headspace in these cartridges) at the same time, the rimmed and belted cases have to be designed to first take the worst case tolerance for excess headspace to the rim or belt seat, then add minimizing the shoulder length enough to avoid stopping against the chamber shoulder of a minimum shoulder dimension chamber first. In other words, they have to plan for a chamber with the shortest shoulder and the deepest rim or belt headspace at the same time. This means making an extra short shoulder. Standard resizing dies are set up to put a case back to approximate factory new condition. But since you own the rifle, you can ignore all that stuff the manufacturers need to worry about and test feed without having to make the ammo to fit all 30-30 chambers. So you can simply back your resizing die out of contact with the shell holder by, say, a quarter turn (about 18 thousandths), and see if the resized cases coming out will still chamber smoothly. If so, back out a bit more. Find where the cases stop feeding as smoothly as you want or where the closing the bolt on them starts to give you resistance in the lever. This will minimize how much you resize the brass. Incidentally, to further preserve brass and maybe improve accuracy, a lot of rimmed and belted cartridge shooters intentionally resize to let the case seat on the shoulder instead of the rim, as described in an earlier post. I know of no reason not to do this unless it worsens your group sizes or interferes with feeding.
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September 21, 2018, 11:48 AM | #11 | |
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There is another length that is measured from the datum to the end of the neck; a good understanding of the different length of the case helps the reloader understand what happened to the case when fired. F. Guffey |
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September 21, 2018, 12:17 PM | #12 |
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Case length is not measured to or at the shoulder. They're measured from the case mouth to the flat part of the case head. SAAMI Max case length for the .30-30 is 2.0395" -.020". That makes the minimum 2.0195".
SAAMI spec length from the flat of the case head to the shoulder is 1.4874" -.015. That's a MAX of 1.4874" and a minimum of 1.4724". Full length resizing is all you need to do. Lever actions require FL resizing every time anyway. "...Larry Willis digital headspace gauge..." That is not a headspace gauge. Like F. Guffey says, it's a dial indicator that tells you nothing you need to know. Cases do not have headspace. And the .30-30 headspaces on the rim, not EVER on the shoulder.
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September 21, 2018, 12:33 PM | #13 | ||
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However, H&R/NEF single-shot .30-30s tend to be the most common source of brass fired in really sloppy chambers. If you bump the shoulder back and keep it there, the brass should be just as good as anything else. Quote:
Lever guns can be run just like bolt actions. Depending upon the load, brass, chamber, etc., neck-sizing may be all that's necessary Take it case-by-case. .30-30 can quite easily be set up to headspace on the shoulder, by a reloader that knows what they're doing - especially if using brass that has minimum-spec rims, in a rifle at or near maximum headspace. Doing so greatly reduces case stretch, prolongs case life, and can improve accuracy.
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September 22, 2018, 06:56 AM | #14 |
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Thanks for the creative feedback guys, 30-30 lever is new to me . Like i commented im going to re-size the shoulders just enough to allow a nice clean chambering. Common knowledge is dont work the brass any more than necessary.
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September 22, 2018, 09:09 AM | #15 |
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You've got the right idea. Again, forcing the shoulder back so the case has to headspace on the rim is just a manufacturing consideration since the rim seating surface is the only one the rifle maker can be certain to have gauged, leaving the shoulder a variable location. You don't have to rely on gauged values because you own the rifle and can fit the ammo to it. It's really that simple. Not having to limit oneself to manufacturer's considerations is one of the benefits of handloading in general, so take advantage of it.
BTW, a lot of 303 British owners stick thin O-rings over their new brass and down against the rim so that when they chamber it forces the case head back against the breech and lets the shoulder blow forward so they can then do exactly what you are talking about doing, but never have any initial expansion ring stretching near the head. You can also make a steel excess headspace filling shim washer to do this within a thousandth for your exact chamber and brass tolerances. That and periodic annealing and using a bushing neck die will make the brass last almost indefinitely with CAS loads.
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September 22, 2018, 11:09 AM | #16 | |
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Again, I do not know how your guys do it with all of the bumping going on; moving the shoulder back and moving the shoulder forward. My life is not complicated with things I do not understand. F. Guffey |
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September 22, 2018, 01:33 PM | #17 | |
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They new most new shooters were going to buy one anyways so why should they. The sales of the 94's proved this. If the shells you were given came from one of those old Winchesters then, Yeah, It could be considered normal. There is a but load of them out there. I headspace off the shoulder for all my 30-30s but they are JM Marlin's, I get better accuracy with them by head spacing off the shoulder. |
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September 22, 2018, 07:34 PM | #18 |
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Concepts, which can have multiple descriptions....
Cases are not ever "shortened" (unless trimmed). Shoulders are never bumped back (but rather, "relocated"). Brass stretch is better referred to as, "dimension stretch" or rather, "fire formed to fit the chamber". "Case size" and "Headspace" are often referred to as being the same concept (but with different choice of words)... Cases do not have "Headspace" (but their multiple measurements/multiple dimensions can be used to describe and offset those dimensions of a given "Headspace"), in an explanatory way.... Finally, I think I'm grasping this all.. Thanks... Last edited by eschafer; September 22, 2018 at 09:50 PM. |
September 23, 2018, 07:34 AM | #19 |
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Resize the cases and see if they fit your rifle's chamber......If they chamber easily it doesn't really matter what SAMMI says . Rimmed cases "head space" on the rim not the case shoulder .
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September 23, 2018, 10:28 AM | #20 |
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There seems to be a lot of angst about the shoulder terminology. Here's an exaggerated illustration I made of what happens to brass during resizing:
Note that when a bottleneck rifle case expands in a chamber it typically sticks to the sides and stretches at the pressure ring. This lengthens the distance from the head to the shoulder. This is said to be moving the shoulder forward, even though it actually moves the head back from the center of the case volume. That measurement change is true anyplace on the shoulder that you choose to measure it. It'll be true if you measure from the head to the datum diameter on the shoulder or if you improvise by measuring a diameter that falls someplace else on the shoulder, as shown below. But either way, as long as you measure the same diameter, you will see that length changes. When you resize, because the stretched pressure ring is thicker than the brass at the shoulder and neck, the pressure ring is not pushed back to size. Instead, as the case is forced into the die it is first squeezed a little narrower and longer and then, when the shoulder of the case meets the shoulder of the die, the brass begins to be extruded up into the neck. This means a little of the brass that was part of the top end of the shoulder flows into and becomes part of the neck or part of the internal donut ring at the neck and shoulder junction, and a little of the brass that had been the sides of the case at the bottom edge of the shoulder is flowed up to become part of the shoulder. So Mr. Guffey is correct to say the shoulder is not moved or bumped back in the sense of relocated the exact same atoms of brass alloy up or down, but rather the shoulder comes to be comprised of mostly the same atoms with some new ones coming from the sidewalls of the case body by extrusion. The location of the datum diameter (or any other diameter on the shoulder) is then changed with respect to the location of the head. It's a plastic flow. But to the layman it certainly appears the shoulder changed location so that is how it came to be generally described as setting a shoulder back or, if the setback is very small, "bumping" it back.
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