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Posted: 1/18/2014 7:12:21 PM EDT
| I'm new to reloading, <500 rounds under my belt. I started with just a speer manual because thats what my rock chucker came with. Over the past year I've acquired a hornady, sierra, and lyman manual. Tonight I put together some test loads for a browning abolt 2 target in .308 using hornady 168gr hpbt. Hornady shows much lower charge weights than the others. Are hornady's bullets that different. Are they overly cautious? I know, work up.And yes, I enjoy load development. But just starting out in the past year and a half I don't exactly have a lot of powder to burn. When the Hornady max falls almost in the middle of other manuals minimums and maximums it makes me think that I could burn through a lot of powder going by the hornady manual. Is this a non-issue? Should I always go by bullet manufacturer info? Should I only go by powder manufacturer info. Should I use an average of the bullet and powder manufacturer info? I guess what I'm saying is I'd like to be as effecient as possible with my time and resources and the large difference in charge weights between the manuals makes that impossible with a spread of about 13 grains between manuals. |
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If you care to narrow the topic down to a real specific bullet + powder (+ primer) combination, we could give you more specific advise.
Your point is very good. Sometimes the differences are just safety margin and sometimes the performance is due the test rig chambers and bores (not to mention bbl lengths). For the most common powders and designs these days, the pressure results would be much more reproducible from lab to lab if the test rigs were more identical. We really have some fantastic powders and components to work with these days. However, you can see that with differences in how the authors deal with test rigs and margins, the books will show significant differences in the charges and velocities. There are too many differences to discuss, but it may be possible to help with a more specific recipe and gun. |
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You might want to get a Lee Reloading manual. IIRC they test and publish the widest variety of load data across a broader spread of powders, bullets, and such. Also look at the manuals you have to see if they have a chart showing RELATIVE burn rates for various powders. Look carefully at all of the components in case there are differences in cases, primers, bullets etc. Wth any manual the basic assumption is that the loads were safe in the particular set up that company used during their testing.
Caveat #1Always reduce your start load by 10% from the published maximum. Caveat #2. You will never know what your loads are doing without a chronograph. Good ones can be had for $100-$150, adequate for 85% of all reloaders Caveat #3. Visible pressure signs not generally repeatable, and only a very coarse guide. Caveat #4. Own a reliable and accurate dial or digital caliper. It will tell you if you have abnormal case expansion, sometimes. IMH experience if their is more than 3-4 grains difference from manual to manual, I' probably going to look for other recipes. Generally I look for loads that give me 90% or better load density, and not getting into compressed loads. In loading for 7 rifle calibers and 5 pistol calibers, I have never had a load that was the most accurate load at maximum load capacity. YMMV. I look for economy and accuracy first. I hope this helps. 44-40pro |
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There are some difference in manuals and some differences in components. 308 Winchester cases can vary in case capacity. Primers can vary in strength. Hornady has a, "308 Winchester Service Rifle" section based on gas port pressure of an M1A1 rifle using Hornady A-Max bullets. They are a bit longer than standard match HPBT bullets. The Hornady manual is set up in velocity columns. If a powder can't make the next column of velocity and stay within pressure limits, then the top load for that powder is the previous column of velocity. The top load in the Hornady may not be the absolute maximum load. 50 feet per second won't make any difference out to 600 yards. 100 fps may not make much difference. The Speer manual is rounded off or rounded up. The data in the Speer manual and Lyman manual haven't been updated often. The Sierra manual hasn't been updated in a while. The Hornady number nine manual is one of the newest, but much of its data is from earlier versions. Some data in it is very new, with newer powders.
Avoid current production Winchester primers. They leak around the primer cup. Avoid Federal and Nosler (also made by Federal) cases. They are soft and thin in the case head and expand excessively around the primer pocket. Remington cases are soft but seem to hold up fairly well. Winchester cases have the largest capacity and are thin but usually have proper heat treatment and hardness. Most 168 grain HPBT bullets are very similar. Sierra, Hornady, Speer and Nosler are all very similar in design. The, "Mil Spec" brand and Prvi 168 grain bullets are very different and often difficult to load. They don't have much bearing surface for case neck tension. Seating them properly can be difficult. Military cases have about the smallest capacity. Federal cases have similar capacity but with thick, soft walls and weak, thin case heads. Remington cases can vary quite a bit in weight and capacity but have slightly larger capacity than military cases. Not much though. Winchester cases have the largest capacity. Winchester cases are the same as Black Hills and most Hornady and Frontier cases. Federal cases are the same as Nosler cases. The best primers are Federal and CCI. While Remington primers can be acceptable. Winchester primers can be nothing but trouble these days. There is also load data on the powder company websites. They usually make their own powders look best, or strongest, so the maximum loads they show can be hot. The Sierra 308 Winchester load data isn't usually the hottest but the Sierra data and velocities are about right for the 26 inch barrel they use. Used military and government contract type (law enforcement) cases will often, if not usually, have crimped primers. These will require removing the crimps after decapping the old primers before seating new primers. There are different tools and methods for doing this. |
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For starters -
Hornady switched to piezo gage pressure measurement several years ago and as a result the maximum loads in their manual reflect the peak measured pressure. Crushers cannot pick out the true peak pressure, but what they do measure is the total work during the ignition - burn cycle. No one is blowing up guns by carefully applying basic reloading principles and using CUP based data. Here's the method I recommend for handling disparate data from several sources - - Gather up the maximum charge weights from all your sources - Let the minimum charge and the maximum charge from your sources represent the range of possible maximum charge weights; in other words, the maximum charge weight you find from working up a load could occur anywhere in that range. - Calculate the average of the maximums - Calculate a charge weight 90% of the average of the maximums. If that weight is greater than all of the minimum charge weights found, then use that as the starting charge weight. If it is less, then use the minimum of the published charges. - Proceed with your load work up. The standard modern rule of thumb for reducing start loads is 10% down from the maximum. I use that when I load a new cartridge that I've never loaded before or when I use a new gunpowder I've never used before. But if I'm loading a familiar cartridge with a familiar gunpowder I usually use a start load 5% less than maximum, or sometimes 7% if I think there's something snakey about the load, say using a copper bullet or one that I know has a thick jacket, blunt ogive, or unusually long bearing surface. New reloaders burn up lots of components, barrels, and time by using too much caution when incrementing charge weights, and although that is instructive once or twice as it gives some sense about the differences from load to load, after a while it's time to start shooting. We've seen lots of new reloaders using 0.1 or 0.2 grain increments, and when that is combined with a matrix of primers and gunpowders, the amount of work is enormous and it might lead to no conclusion. Try that with over bore cases and you'll find the throat is shot of the barrel about the time you've settled on a load. |
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My newest Hornady manual is the 8th edition. Before that it was the 3rd. Yes the new one seems to be lower across the board or at least for many loads. This is why its good to use several sources. You must also keep in mind that these are "reference manuals" that provide you with a safe starting point.
Most of them also state that the data does not exceed the SAMMI max. But that was in what ever they used to test it with. You have to do your own development. This does not mean you ignore the "max" listed data but in some cases you may find that your best load IS over the max in at least one data source. It happens. If you used my 1985 Speer manual as your only data source and loaded to max you would be over max in just about anything published for the last 15 years or more. There are also occasional misprints. Another good reason to cross reference. |
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The Hornady data is very good and reflects my experience regarding velocity produced with their loads when using a chronograph. In particular, their service rifle data, M1-A and M-1 Garand loads are GTG.
They are not reduced to prevent us from "putting our eyes out". It reflects their testing in their rifle, brass, powder charge, primer and bullet combination. This difference is greatest when changing primers. Winchester standard large rifle primers, Federal's 210M and CCI's military primers are the hottest. CCI-200, CCI-250, Remington 9 1/2 and Wolf (Russian) large rifle primers are milder. Almost 6000 psi reduction (or increase) in pressure depending on which primer is used. Hot primers increase pressure, milder primers reduce it. |
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Quoted:
I'm new to reloading, <500 rounds under my belt. I started with just a speer manual because thats what my rock chucker came with. Over the past year I've acquired a hornady, sierra, and lyman manual. Tonight I put together some test loads for a browning abolt 2 target in .308 using hornady 168gr hpbt. Hornady shows much lower charge weights than the others. Are hornady's bullets that different. Are they overly cautious? I know, work up.And yes, I enjoy load development. But just starting out in the past year and a half I don't exactly have a lot of powder to burn. When the Hornady max falls almost in the middle of other manuals minimums and maximums it makes me think that I could burn through a lot of powder going by the hornady manual. Is this a non-issue? Should I always go by bullet manufacturer info? Should I only go by powder manufacturer info. Should I use an average of the bullet and powder manufacturer info? I guess what I'm saying is I'd like to be as effecient as possible with my time and resources and the large difference in charge weights between the manuals makes that impossible with a spread of about 13 grains between manuals. It helps us when reading your post if you break the sentences up with double spacing after you ask a specific question or change topic slightly. It's much easier to respond if we don't have to fight through a wall of text. 42.0 grains of IMR-4064 under a 168 grain match bullet is a standard .308 accuracy load. So is 41.5 grains of IMR-4895, or 41.0 grains of H-4895. Reduce these charge weights by 1.0 whole grain if you use Lake City (military) brass. |
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Quoted:
For starters - New reloaders burn up lots of components, barrels, and time by using too much caution when incrementing charge weights, and although that is instructive once or twice as it gives some sense about the differences from load to load, after a while it's time to start shooting. We've seen lots of new reloaders using 0.1 or 0.2 grain increments, and when that is combined with a matrix of primers and gunpowders, the amount of work is enormous and it might lead to no conclusion. Try that with over bore cases and you'll find the throat is shot of the barrel about the time you've settled on a load. This is what I am trying to avoid. I like your method of averaging, reducing, and seeing where that compares with printed loads. If I was working up a plinking load I wouldn't worry about this, but this load in this gun is about accuracy and I'd like to be as efficient as possible while finding that load. Especially when I'm having to figure out which powder works best. For example, if I test varget using just five shot groups moving up in .5gr increments, I would shoot 27 5-shot groups going from absolute lowest charge weight( 33gr.hornady manual) to the highest(46 gr. Speer). That's 135 shots just for one powder. Shoot five different powders and you're looking 675 shots. It just seems there would be a more efficient way. Thanks for the continued input. I'm getting something out of each answer. |
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One short cut that gets overlooked is a probe to determine the maximum charge.
Instead of shooting 5 or 10 shots with each charge in turn, shoot one shot (or at most two shots) at each charge, then make a decision about the likely maximum you'll find later. Load off that charge weight with an eye toward confirming the original test. By watching the progression through those shots you may develop enough confidence to use a new starting load that is less conservative. Keep in mind that loads from winter testing have to be eyeballed carefully when the temps turn hot. |
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Very good point AeroE.
That is how I start any "new" load. Depending on the caliber, I go with 1/2 or 1gr increments and "shoot for pressure". If you do this while shooting on paper and over a chronograph it can save you a ton of time. I usually go right up to and a little over "book" max. Rarely do I even shoot the "over max" load but at times I have had rifles that don't show pressure or expected velocity until over the book max. When developing the load for my 300 Rem SAUM it only took a few rounds shot over the chroney to find a load that I wanted to group test. I still use that load. |
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