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Posted: 5/12/2012 9:39:58 AM EDT
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Where can I find one? I have the Hornady gauge but can't find what headspace is supposed to be for 25-06, 30-30 etc. The reloading manuals seem to leave this number out of their specs. |
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Where can I find one? I have the Hornady gauge but can't find what headspace is supposed to be for 25-06, 30-30 etc. The reloading manuals seem to leave this number out of their specs. You'll need to find the 'technical drawings' for each cartridge. Preferably one that specifically tells you where the datum line is 'at' for that cartridge. Don't count on being able to figure it all out, or even measure it. Go/No Gages would allow you to test your chambers for safety, as well, if you're worried. If it's a new (read: safe) weapon, take fired cases, measure them with your Hornady headspace bushing and then take that measurement and set your sizing die up to bump your shoulders back .002"-.003" from the fired measurement and you'll be peachy. That's how those gages are to be used. Chris |
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Quoted: That's what I did. I found one on-line source for the head space numbers putting it between 2.0487 and 2.0587, Factory 25-06 measures about 2.041, my once fired cases are 2.045 and the ones I full length sized with Redding dies are 2.047. I found it odd because the once fired came from the same full length sized group. It appears my cases are shrinking. Rifle is a Remington 700 maybe 100 rounds fired and it shoots fantastic. The once fired cases I measure gave a group size of 3/4" at 100 yards at published Hornady velocity with no pressure signs. I did notice the tight fit when closing the bolt so I bought the gauge. The sizing die was just touching the shell holder.Quoted: Where can I find one? I have the Hornady gauge but can't find what headspace is supposed to be for 25-06, 30-30 etc. The reloading manuals seem to leave this number out of their specs. You'll need to find the 'technical drawings' for each cartridge. Preferably one that specifically tells you where the datum line is 'at' for that cartridge. Don't count on being able to figure it all out, or even measure it. Go/No Gages would allow you to test your chambers for safety, as well, if you're worried. If it's a new (read: safe) weapon, take fired cases, measure them with your Hornady headspace bushing and then take that measurement and set your sizing die up to bump your shoulders back .002"-.003" from the fired measurement and you'll be peachy. That's how those gages are to be used. Chris |
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Where can I find one? I have the Hornady gauge but can't find what headspace is supposed to be for 25-06, 30-30 etc. The reloading manuals seem to leave this number out of their specs. Go to this link - SAAMI web site. Under the heading of "Information and Specifications", click the "Cartridge and Chamber Drawings" link This opens a pdf file listing all the cartridges. Select the one you are interested in and click the line item. It opens an engineering drawing of the cartridge showing all the dimensional data. The NRA sells a paperback book with all these chamber and cartridge drawings in the back. They are great to have on hand. The drawings are worth the purchase price of the book, alone. |
| Your Hornady/Stoney Point gauge uses a "Comparator" to measure the case. A comparator is just that, it compares. It compares or measures the changes you make at YOUR loading bench. It does not measure to the SAAMI exact Datum line of the shoulder. If the "Comparator" was to land exactly on the SAAMI datum line of the shoulder Hornady would have to make one for each and every cartridge made. They do not, they have a few that work with dozens of different cartridges, all of which have different SAAMI datum measurements. Some handloaders have even made their own "Comparitors" out of straight walled pistil cases. |
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my once fired cases are 2.045 and the ones I full length sized with Redding dies are 2.047. I found it odd because the once fired came from the same full length sized group. It appears my cases are shrinking. Do you mean, that after sizing the 2.045 cases they come out of the die at 2.047? If so, you are not pushing the shoulder back when you resize. The case is being "squeezed" and the shoulder is moving forward. If not, disregard! If so, read on. You mentioned that the "sizing die was just touching the shell holder". That is where your issue is occuring. There is some slack in the press when setup this way. The press typically needs to "cam over" a bit. Start by running the die in until it touches the shell holder. Then check the length of the fired case from base to datum line. Resize the case. Check the measurement again and adjust the die down in small increments, re-measuring until you have "bumped" the shoulder back the desired amount. I use .001 under for precision rifles, .002 for bolt action hunting rifles and .003 for semi's. |
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Quoted:
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my once fired cases are 2.045 and the ones I full length sized with Redding dies are 2.047. I found it odd because the once fired came from the same full length sized group. It appears my cases are shrinking. Do you mean, that after sizing the 2.045 cases they come out of the die at 2.047? If so, you are not pushing the shoulder back when you resize. The case is being "squeezed" and the shoulder is moving forward. If not, disregard! If so, read on. You mentioned that the "sizing die was just touching the shell holder". That is where your issue is occuring. There is some slack in the press when setup this way. The press typically needs to "cam over" a bit. Start by running the die in until it touches the shell holder. Then check the length of the fired case from base to datum line. Resize the case. Check the measurement again and adjust the die down in small increments, re-measuring until you have "bumped" the shoulder back the desired amount. I use .001 under for precision rifles, .002 for bolt action hunting rifles and .003 for semi's. Good catch, this if very important. If your brass measured at the shoulder is growing you need to adjust your FL die deeper into the press. |
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Quoted:
Quoted:
That's what I did. I found one on-line source for the head space numbers putting it between 2.0487 and 2.0587, Factory 25-06 measures about 2.041, my once fired cases are 2.045 and the ones I full length sized with Redding dies are 2.047. I found it odd because the once fired came from the same full length sized group. It appears my cases are shrinking. Rifle is a Remington 700 maybe 100 rounds fired and it shoots fantastic. The once fired cases I measure gave a group size of 3/4" at 100 yards at published Hornady velocity with no pressure signs. I did notice the tight fit when closing the bolt so I bought the gauge. The sizing die was just touching the shell holder.
Quoted:
Where can I find one? I have the Hornady gauge but can't find what headspace is supposed to be for 25-06, 30-30 etc. The reloading manuals seem to leave this number out of their specs. You'll need to find the 'technical drawings' for each cartridge. Preferably one that specifically tells you where the datum line is 'at' for that cartridge. Don't count on being able to figure it all out, or even measure it. Go/No Gages would allow you to test your chambers for safety, as well, if you're worried. If it's a new (read: safe) weapon, take fired cases, measure them with your Hornady headspace bushing and then take that measurement and set your sizing die up to bump your shoulders back .002"-.003" from the fired measurement and you'll be peachy. That's how those gages are to be used. Chris The cases expand to fill the chamber upon firing, and since they don't spring back to their original dimensions, the overall length will be shorter even though a measurement from the head to shoulder datum is longer than the unfired cases. After sizing the shoulder has been set back and the body squeezed down, so the overall length increases a few thousandth's. Plus, each time the case is fired, some of the brass in the neck migrates toward the end, causing the neck to become slightly thinner. These are the reasons brass must be trimmed after sizing. When we discuss "headspace" with respect to reloading, it refers to the actual dimensions of the fired cases, sized cases, and the actual chamber they were fired in. So, we measure the length of the fired cases, determine the distance to set the shoulder back, and then adjust the sizer die to produce that dimension. The rule of thumb is to set the shoulder back 0.002 to 0.008 inches for most any rifle (except tight chambered guns with custom chambers operated by experienced reloaders), however I have measured new Winchester White Box .223 Rem ammunition 0.014 inches shorter than the fired cases from a couple of rifles, one a off the rack Colt, the other a custom rifle. An AR will operate reliably with 0.0015 to 0.002 inches of headspace, and that's generally where I set my die, but if it lands on 0.003 inches I press on. Good lube and uniform lube is required to control the dimension. We don't need the drawings for a chamber headspace gage or chamber reamer by operating this way. To insure operation in a large number of rifles just a little more case headspace might be required, say 0.004 to 0.005 inches, but I've not run across one in my own shooting. What we do need is a method for measuring headspace. The fixed drop in gages made by Wilson and Lyman cause the sizer die to be set up to produce 0.008 inches. The adjustable gages with a caliper can be used to set the case headspace at any length desired, and this is the type I recommend, either the Hornady tools or the Sinclair tools. |
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Quoted: They were longer after sizing. Today I turned the die until it just touched the shell holder than just a little more, the cases came out at 2.042. So it appears I was just not turning the die down enough. I will now set it to size .003 under the once fired. Thanks again.Quoted: my once fired cases are 2.045 and the ones I full length sized with Redding dies are 2.047. I found it odd because the once fired came from the same full length sized group. It appears my cases are shrinking. Do you mean, that after sizing the 2.045 cases they come out of the die at 2.047? If so, you are not pushing the shoulder back when you resize. The case is being "squeezed" and the shoulder is moving forward. If not, disregard! If so, read on. You mentioned that the "sizing die was just touching the shell holder". That is where your issue is occuring. There is some slack in the press when setup this way. The press typically needs to "cam over" a bit. Start by running the die in until it touches the shell holder. Then check the length of the fired case from base to datum line. Resize the case. Check the measurement again and adjust the die down in small increments, re-measuring until you have "bumped" the shoulder back the desired amount. I use .001 under for precision rifles, .002 for bolt action hunting rifles and .003 for semi's. As a side note any ideas on where I should set my dies for my M1A. The headspace is 1.632 same with the once fired brass. Factory brass is 1.618-1.620. Where can I set it and still be safe and reliable? And will it even make a difference in case life as I understand the M1 action is rough on brass? |
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Your Hornady/Stoney Point gauge uses a "Comparator" to measure the case. A comparator is just that, it compares. It compares or measures the changes you make at YOUR loading bench. It does not measure to the SAAMI exact Datum line of the shoulder. If the "Comparator" was to land exactly on the SAAMI datum line of the shoulder Hornady would have to make one for each and every cartridge made. They do not, they have a few that work with dozens of different cartridges, all of which have different SAAMI datum measurements. Some handloaders have even made their own "Comparitors" out of straight walled pistil cases. I don't understand why you would think this. The SAAMI datum diameter is manifest in the gage insert. |
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Quoted:
Quoted:
Your Hornady/Stoney Point gauge uses a "Comparator" to measure the case. A comparator is just that, it compares. It compares or measures the changes you make at YOUR loading bench. It does not measure to the SAAMI exact Datum line of the shoulder. If the "Comparator" was to land exactly on the SAAMI datum line of the shoulder Hornady would have to make one for each and every cartridge made. They do not, they have a few that work with dozens of different cartridges, all of which have different SAAMI datum measurements. Some handloaders have even made their own "Comparitors" out of straight walled pistil cases. I don't understand why you would think this. The SAAMI datum diameter is manifest in the gage insert. Doesn't matter. Pick a diameter on the shoulder that isn't on the tangency of the corner to the body or neck, and press on. I'm not going to pore over dozens of chamber drawings to find out whether the 5 datum diameters ranging from 0.330 to 0.420 inches sold by Hornady are used for every cartridge in the SAAMI catalog, because it's apparent they can't be. |
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As a side note any ideas on where I should set my dies for my M1A. The headspace is 1.632 same with the once fired brass. Factory brass is 1.618-1.620. Where can I set it and still be safe and reliable? And will it even make a difference in case life as I understand the M1 action is rough on brass? You might want to post this question in the M1/M1A forum for a more complete answer, but my understanding is that the Hornady comparator is not to be used for fired brass from your M1A in the same way as you'd use it for a bolt gun because the extraction will actually stretch the case to bigger than chamber dimensions. This will lead to cases that are not sized enough and they will be tough as shit after the cheese party at the retirement home to extract, if you can get them to chamber at all - ask me how I know  (not the part about the tough shit after the cheese party, the tough extraction part) 
For my M1A, I used it to compare to Federal gold medal match and set my die up to match that measurement. I might play around with the headspace later after I get more experience reloading, but for now its working. Good luck. |
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<snip> I'm not going to pore over dozens of chamber drawings to find out whether the 5 datum diameters ranging from 0.330 to 0.420 inches sold by Hornady are used for every cartridge in the SAAMI catalog, because it's apparent they can't be. Actually, the gage inserts are to the SAAMI spec for each cartridge. For example, that is why the .308 Winchester insert (0.400" diameter) is different than the .30-06 insert (0.375" diameter). The inserts work for all cartridges which have the same datum diameter. For example, the 0.400" insert also works for 7mm-08 and 243 WInch and many others. However, sometimes, there are other issues at play which are not self-evident. If he knows of some, I'd like to see them. |
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<snip> I'm not going to pore over dozens of chamber drawings to find out whether the 5 datum diameters ranging from 0.330 to 0.420 inches sold by Hornady are used for every cartridge in the SAAMI catalog, because it's apparent they can't be. Actually, the gage inserts are to the SAAMI spec for each cartridge. For example, that is why the .308 Winchester insert (0.400" diameter) is different than the .30-06 insert (0.375" diameter). The inserts work for all cartridges which have the same datum diameter. For example, the 0.400" insert also works for 7mm-08 and 243 WInch and many others. However, sometimes, there are other issues at play which are not self-evident. If he knows of some, I'd like to see them. They will also work on any cartridge where the gage bushing doesn't ride on the radius at the transitions, or even on a Weatherby case with a near hemispherical shape. These are comparators and absolute dimensions are not required for sizing a case. I have used 5/16th's and 3/8th's ID bushings out of a bin and a caliper when I needed to troubleshoot someone's ammunition and the "proper" gages weren't handy. It works, and it also points up that reloaders don't really need to buy the Hornady or Sinclair kit to accomplish the same thing, although their gages are a little easier to handle when trying control the bushing, case, and calipers and get everything squared up. Works with measuring bullet ogives, too. Hornady sells bushings in 0.330, 0.350, 0.375, 0.400, and 0.420 inch diameters. I arbitrarily grabbed two cartridges without hunting in ANSI-SAAMI Z299.4; 7.62X39 has a 0.3622 inch diameter datum, 8mm Mauser has a 0.392 inch datum, 218 Bee has a 0.2875 inch datum, .22-250 has a 0.347 inch datum, 220 Swift has a 0.335 inch datum, and so on. Some cartridges have mid shoulder datums defined, and some do not. The 0.375 datum for .30-06 is very close to the neck transition, the diameter at the body transition is 0.4425, and I have no doubt I would use the 0.400 bushing from the Hornady kit, and have. |
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Absolute measurements of chamber length are a real PITA (and rarely made).
Even when chambering we just use gauges and make to stay between the go and no-go. We get a lot of relief by only needing relative measurements to size cases. You are just trying to create enough case clearance to allow easy chambering, without allowing excessive brass stretch on firing. |
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