Looking for Hornady Load data
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Hmmm.... You got something there. Looking at the chart it seems like there is not consistent correlation between seating depth and pressure. Some of the charts show increase from left to right and some a decrease. The 30-06 shows an increase in pressure with ball powder and a decrease with extruded powder. What it does prove is that when I made the statement " As a general rule seating a bullet closer to the lands will give you better accuracy and reduced pressure" I was incorrect in regard to pressure. Sorry about that.
The Hornady website has a section on "Internal ballistics". They describe the effect of the distance a bullet is seated and how it affects pressure. Oddly enough I remember reading this a few years ago and am now giving advice to the contrary. Lots of good illustrations and description of internal ballistics.
www.hornady.com/ballistics-resource/internal
The rule of thumb for seating bullets one bullet diameter into the case is an old one. I follow that quite a bit when loading bullets without a cannalure. When there is a cannalure I seat the bullets so a tiny crack of the cannalure is visible. Essentially the neck will be crimped against the top edge of the cannalure.
The old rule of thumb as I remember it was something like: "Seat the bullet at least one diameter into the neck, or as much further as is required to fit the magazine and feed reliably."
Of course since it's a "rule of thumb" there is no set wording for it and there will always be a little wiggle room. You can just use the SAAMI COAL's for all cartridges but most get better accuracy with reduced bullet jump. Some bullets, VLD or very low drag long range match bullets in particular, are very jump sensitive and you really want to reduce the jump for optimum accuracy.
If the rounds fit in your magazine and feed properly, your COAL is just fine, all you have to do is keep it consistent for consistent results.
The safest COAL that most firearms will be designed to work well with (especially semi autos) is the SAAMI published COAL. For 223 I believe it's 2.26" but I haven't double checked that. You can find listings online or at the SAAMI website. Some reloading manuals use the SAAMI length, others use their made up COAL's. Generally I totally ignore any listed COAL's in any reloading manual as they are either SAAMI or just totally made up (really). Keep it consistent and you will get consistent results, the actual value doesn't matter. You seem to be putting a lot more thought into this than you have to. If you pick one COAL and keep it the same for all your reloads, then start at the starting load and work up to find whatever optimum you are looking for (accuracy or velocity usually) and once you find it, keep the COAL the same, you will never have to think about it again.
The only time I try changing the COAL is for reducing bullet jump to try to increase accuracy. I usually end up with a cartridge that is too long for my magazine and I have to single feed them into the chamber. SAAMI for 308 is 2.800" but my loads with the bullet touching the lands is 2.950" and will no longer fit in the magazine. My 6.5x55 is even longer because of the European style long throats. Published COAL is 3.150" and I'm at a little past 3.500". Cartridges are over 1/4" too long for the magazine. I only do this for match style bullets to see what the rifle can do. In general I do get better results with this method but of course it's less practical for many applications.
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TL;DR
Pick a COAL, it REALLY doesn't matter which (SAAMI, book, whatever) and stick with it for all your reloading of that cartridge. Don't change it and don't think about it ever again unless looking at advanced reloading.
The old rule of thumb as I remember it was something like: "Seat the bullet at least one diameter into the neck, or as much further as is required to fit the magazine and feed reliably."
Of course since it's a "rule of thumb" there is no set wording for it and there will always be a little wiggle room. You can just use the SAAMI COAL's for all cartridges but most get better accuracy with reduced bullet jump. Some bullets, VLD or very low drag long range match bullets in particular, are very jump sensitive and you really want to reduce the jump for optimum accuracy.
If the rounds fit in your magazine and feed properly, your COAL is just fine, all you have to do is keep it consistent for consistent results.
The safest COAL that most firearms will be designed to work well with (especially semi autos) is the SAAMI published COAL. For 223 I believe it's 2.26" but I haven't double checked that. You can find listings online or at the SAAMI website. Some reloading manuals use the SAAMI length, others use their made up COAL's. Generally I totally ignore any listed COAL's in any reloading manual as they are either SAAMI or just totally made up (really). Keep it consistent and you will get consistent results, the actual value doesn't matter. You seem to be putting a lot more thought into this than you have to. If you pick one COAL and keep it the same for all your reloads, then start at the starting load and work up to find whatever optimum you are looking for (accuracy or velocity usually) and once you find it, keep the COAL the same, you will never have to think about it again.
The only time I try changing the COAL is for reducing bullet jump to try to increase accuracy. I usually end up with a cartridge that is too long for my magazine and I have to single feed them into the chamber. SAAMI for 308 is 2.800" but my loads with the bullet touching the lands is 2.950" and will no longer fit in the magazine. My 6.5x55 is even longer because of the European style long throats. Published COAL is 3.150" and I'm at a little past 3.500". Cartridges are over 1/4" too long for the magazine. I only do this for match style bullets to see what the rifle can do. In general I do get better results with this method but of course it's less practical for many applications.
--------------------------------------------
TL;DR
Pick a COAL, it REALLY doesn't matter which (SAAMI, book, whatever) and stick with it for all your reloading of that cartridge. Don't change it and don't think about it ever again unless looking at advanced reloading.
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Be very careful looking for "overpressure" from signs or markings on the brass. Different brands of cases will show "signs of overpressure" at different pressures regardless of what the maximum rated pressure for a given cartridge is. The brass or primer can't know what the maximum pressure of the cartridge it happens to be sitting in is rated for. How can it, it's an inanimate object?
A 30-30 is a 42,000 psi cartridge
A 308 is a 60,000 psi cartridge
A 270 is a 65,000 psi cartridge
All take large rifle primers.
A federal one will partially flatten in a 30-30, really flatten in a 308, and totally flatten in a 270.
A CCI one will not flatten at all in a 30-30, barely flatten in a 308, and partially flatten in a 270.
So if a primer is partially flattening in a 30-30 it could mean you are at a perfectly safe pressure, or you are at 150% pressure and at risk of damaging or destroying your rifle.
Cratering around the indent from the firing pin can be a sign of overpressure. Or it can be a sign of bad headspace. Or it can be a sign that the hole in your bolt face the firing pin moves through is too large. Or it can be a sign that your primers are too soft for this rifle. Or it can be a combination of any of them. Cratering is not a good way to look for overpressure.
Some Hornady brass will start to stick in the chamber at only 60,000 psi.
Federal brass will show extractor marks in the case heads at only 60,000 psi.
Harder brands of brass wont have either until you are past 70,000 psi.
At the end of the day, the only "pressure sign" you can somewhat rely on is the reading on an accurate chronograph when comparing it to the maximum velocity for your barrel length in the published data. Any sort of sign on the case or primer is effected by so many other variables it's like trying to read chicken blood for prophecies. You do have to remember that different powders produce different velocities with the same pressures so you can't just use any velocity data for this comparison; you need to use data specific to your barrel length, bullet weight/construction, and specific powder.
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hometownhero
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Speed also depends if you have a quick barrel or a slow one. Also how tight the chamber is.
Im loading sierra 40gr hp with 28.5gr of h335. In a cz american 21.9" barrel and getting a lot more velocity then the sierra data suggests form a higher charge.
Sierra data shows a max of 29.1gr and that is their hunting load at 3700fps. Barrel length 24"
Im loading sierra 40gr hp with 28.5gr of h335. In a cz american 21.9" barrel and getting a lot more velocity then the sierra data suggests form a higher charge.
Sierra data shows a max of 29.1gr and that is their hunting load at 3700fps. Barrel length 24"
There's nothing in a barrel that can make it faster or slower. You can have a "faster" or "slower" twist rate but that effects the RPM and will have a negligible effect on velocity. If you have a loose bore you can get gas leakage around the bullet and loose pressure and thus velocity. If you have a tight chamber you will increase pressure because there is less volume for the gas to occupy when it is produced. That is why a load needs to be developed for each rifle individually; there are dozens of different major, and hundreds of different minor things that effect how your load performs.
I likewise have a rifle that shoots higher velocity than that published in books. I can reach the published max velocity with a load barely half way between start and max loads. That doesn't mean I have a "fast" barrel or "quick" rifle. It means my rifle is producing higher pressures than the test gun/barrel the lab used to develop the data. I could have thicker brass, a tighter chamber, a barrel with less leakage, a slightly faster burn rate on my lot of powder, or any of many other factors or a combination of them. The velocity measured from my rifle tells me infinitely more than a book written and published with no testing done on my specific rifle can possibly have. I can exceed the maximum published velocity while still below the max published load. I also start to get stiff extractions at that point which could mean I'm at 65,000-70,000psi in a rifle meant for 60,000psi. That's within proof testing ranges but still isn't good for the rifle so I stopped and backed my load down.
I likewise have a rifle that shoots higher velocity than that published in books. I can reach the published max velocity with a load barely half way between start and max loads. That doesn't mean I have a "fast" barrel or "quick" rifle. It means my rifle is producing higher pressures than the test gun/barrel the lab used to develop the data. I could have thicker brass, a tighter chamber, a barrel with less leakage, a slightly faster burn rate on my lot of powder, or any of many other factors or a combination of them. The velocity measured from my rifle tells me infinitely more than a book written and published with no testing done on my specific rifle can possibly have. I can exceed the maximum published velocity while still below the max published load. I also start to get stiff extractions at that point which could mean I'm at 65,000-70,000psi in a rifle meant for 60,000psi. That's within proof testing ranges but still isn't good for the rifle so I stopped and backed my load down.
Maybe i am overthinking it , just diff info in the hornady manual , same bullet weight, diff bullet= diff COL. I'm going to get a chronograph for sure. I'm guessing the load data I'm looking at , on the hornady pages , were done using a 24 inch barrel? ( it didn't say). And I'm using a 181/2 inch barrel. So without ripping me a new AHole , my reloaded 55g vmax , would have less pressure and velocity than a 24 inch barrel.( using the same ammo)
Your pressure will be the same with a shorter barrel because peak pressure is produced usually only when the bullet has moved a few inches. A shorter barrel means there is less time for that pressure to act on the bullet and accelerate it so you will have less velocity. That's why a shorter barrel is usually louder and has a larger muzzle flash. More of the energy is being released by the gas into the air instead of being put into the bullet even though the amount of energy released by the burning powder is the same.
With a 223 you can get complete burn of the powder down to I think less than 10" of barrel.
Are you looking for best accuracy or best velocity?
For best accuracy I just load a bunch of sets from starting to maybe 2/3 to 3/4 published max loads and shoot them. Usually 10rnds of each load for 2 groups of 5 shots each. Those that are promising I make more of and shoot more groups of. Usually I find the peak accuracy load within the first 1/4 to 1/3 of the published load range (fairly low down). Some rifles prefer hotter loads for best accuracy. This is 100% a trial and error process.
For best velocity you can buy some known "warm" factory ammo that is within safe pressure limits (since it's factory ammo this is usually a given). You'll need to do some research to find out which brands are hotter than others. Chrony it and use that as a baseline for your load development. You can also use published data if you have a similar barrel length and load until you hit the velocity they list in the book as the achieved with the max load. Sometimes you will reach it before you reach the actual max load, sometimes you need to go a touch above the max published load before reaching that velocity. Either way if you have the same barrel length (give or take an inch) and are using the same powder the pressures should be close once the velocities match even in a different rifle. If you have a drastically different barrel length than that in the book (like you seem to being almost 6" shorter) you can try to find data elsewhere for velocities with your barrel length. 18"-ish barrels are somewhat common for 223 so you should be able to find some somewhere.
Personally, for 223, I would buy a box of Norinco ammo (known to be quite hot), chrony it in my rifle, and use that as an upper limit when doing load development. I've read reports of it doing 3200fps out of 20" barrels but of course each rifle is different.
With a 223 you can get complete burn of the powder down to I think less than 10" of barrel.
Are you looking for best accuracy or best velocity?
For best accuracy I just load a bunch of sets from starting to maybe 2/3 to 3/4 published max loads and shoot them. Usually 10rnds of each load for 2 groups of 5 shots each. Those that are promising I make more of and shoot more groups of. Usually I find the peak accuracy load within the first 1/4 to 1/3 of the published load range (fairly low down). Some rifles prefer hotter loads for best accuracy. This is 100% a trial and error process.
For best velocity you can buy some known "warm" factory ammo that is within safe pressure limits (since it's factory ammo this is usually a given). You'll need to do some research to find out which brands are hotter than others. Chrony it and use that as a baseline for your load development. You can also use published data if you have a similar barrel length and load until you hit the velocity they list in the book as the achieved with the max load. Sometimes you will reach it before you reach the actual max load, sometimes you need to go a touch above the max published load before reaching that velocity. Either way if you have the same barrel length (give or take an inch) and are using the same powder the pressures should be close once the velocities match even in a different rifle. If you have a drastically different barrel length than that in the book (like you seem to being almost 6" shorter) you can try to find data elsewhere for velocities with your barrel length. 18"-ish barrels are somewhat common for 223 so you should be able to find some somewhere.
Personally, for 223, I would buy a box of Norinco ammo (known to be quite hot), chrony it in my rifle, and use that as an upper limit when doing load development. I've read reports of it doing 3200fps out of 20" barrels but of course each rifle is different.
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As I've only been at this , for a little over a wk, I'm going to just stick with the basics. Since I'm going to be using hornady vmax projectiles, I'll just follow hornady data for now. Once I get a good handle on this , then I'll do more testing. There's a lot to learn.
There is a lot to learn. Ballistic engineers go to school for years and spend decades becoming proficient in this stuff. I'm just scratching the surface as a hobby. Just don't be like some reloaders and go by myth and rumour instead of looking up facts (scientific/laboratory data).
Lutnit your a wealth of knowledge. Thank you for all the info. And Brian im in the same boat as you. Just got a RCBS supreme deluxe kit and have started reloading myself. I got lucky for my .223 rifle (Browning XBolt varmit) and my buddy who has been reloading for a couple years helped tailor a load for me which consists of Winchester Brass, 205M primers, 24.5 gr of Benchmark and Nosler 55gr Ballistic tips. It shoots consistent 5/8" groups at 100yards. So my work for that gun is done. But the reason I asked for Hornady info was that my old man with an identical rifle came to me with a pound of varget. Hornady 55gr vmax and a pile of Hornady once fired brass. So I took the 5 loads listed for that and made 5 rounds of each grain/load. Next step is range and see which is tightest
I'm more of an Accuracy over Velocity guy.
I'm more of an Accuracy over Velocity guy.
