Home Forums Reloading Reloading Software 243 load: Manuals vs. QuickLOAD vs. reality?

A few weeks ago I worked up a load in my 243 Win using H414 in Winchester brass under Speer 70-grain TNTs (and some Hornady 70 grainers as well) loaded to 2.650" COAL. I started low and worked up charge weights just a couple cartridges at a time, always watching for traditional pressure signs that many say are not useful predictors of pressure. While it is clear that the loads are making full pressure, I don't see evidence of major overloading.

I have the newest versions of manuals from Lyman, Speer, Hornady, and Nosler, as well as QuickLOAD at hand. This was all in a Savage 110 (long) action with an Adams & Bennett heavy 24" stainless barrel, though I'm not sure whether that part matters?

One manual lists charge weights of 45.0 - 47.0 grains of H414, or 44.0 - 48.0 grains of the identical Winchester 760 for this bullet @ 2.625" COAL. Another manual lists 43.1 - 49.0 for H414 and 41.6 - 47.3 for W760. The third lists 43.5 - 47.5. That manual has no data for W760 at this bullet weight. The last manual lists 39.6 - 46.9 gr. of W760. Hodgdon's website lists 46.0 grains as max for this powder under a Speer TNT. FWIW, Hodgdon's data hasn't changed since at least 2004 (I have that manual from them). All other sources are 2007 or newer.

Now, the 47.5 grain charge was superbly accurate, and it was really moving. 3639 fps average of 3 shots, which matches almost exactly what Nosler predicted for 47.5 (listed @ 3630 from a 24" bbl). Nosler also said this charge weight was their most accurate for this powder.

Now comes QuickLOAD. When I enter ALL the parameters for my rifle (large-ish fired case capacity, bbl length, etc.) and tweak the burn rate to reach my measured velocity, it predicts that I'm at just under 68,500 psi. For reference, that's ~8,500 psi over max pressure.

Here's my issue/question/whatever. I can't make Nosler's manual numbers work out using QL. Nothing I can do with the numbers will make Nosler's top load predict out to be within industry pressure limits, nor even very close. Everybody else's I can fiddle around enough to at least get close to matching within safe limits.

So, do I decide that QL is mistaken? Do I decide that Nosler's barrel is just a very, very 'fast' barrel? Do I decide that my barrel is equally 'fast?' Do I decide that my chronograph is over 100 fps wrong? It was only 3 shots, but spread among the 3 was very tight. I wouldn't really want to destroy the barrel nor blow myself up, yet at the same time this sure is a nice load.

What would you do?

I use QL and have seen much of the same thing. I have my own range and can reload on site. And I like to experiment. Some thoughts.

We think of 100fps as a lot, but for a 3600fps rifle it is less than 3%.

I have come to accept that velocity cannot be obtained without a corresponding level of pressure, no matter what powder or barrel is used. If you are getting the velocity, you are developing the pressure, with one small exception explained below.

Another factor to keep in mind is that QL estimates based upon 70F barrel temperatures, unless you adjust it. The difference between 70F and 120F barrel temp can cause a 100fps variance (with a corresponding change in pressure). You didn�t say if you are correcting for barrel temperature or not. That may cause some of the anomaly you are seeing.

I have run an enlightening experiment for several cartridge/powder combinations. I started at a very low load and progressed in .2gr increments until I reached very high pressure levels. This generated 50 to 100 data points per combination. I have observed that as powder is increased, velocities advance smoothly for awhile, then stop advancing , then jump (sometimes more than 100fps) and the cycle repeats. If these points are plotted (gr. vs vel) using Excel, and compared to QL prediction, the difference swings back and forth, higher and lower than QL predicts. The best accuracy is usually obtained on one side or the other of the jump. It sounds like you are on top of the jump. I believe this can be explained in terms of the shock waves described in the Optimum Barrel Time Theory. I think that an advancing barrel shock wave boosts the bullet velocity, and a reflected shock wave retards the velocity. This wave travels back and forth several times before the bullet exits the barrel. The wave has the greatest effect on velocity as the bullet nears the muzzle because that is where the pressure is the lowest. Where the pressure is higher, the pressure is the dominant effect. As the pressure drops, the shock wave begins to dominate (near the muzzle). Hope that makes some sense.

What would I do? Back off to the next lower OBT. If you use this load in the summer, or with a hot barrel, you may see dangerous, or at least damaging, pressures.

I agree with you completely re: the relationship between pressure and speed, which is why I got to fiddling around. Having said that, my experience with the OBT hypothesis is that, when I use an OBT table, I get distinctly poor accuracy when I make barrel time match what is supposed to be an accuracy node. This is with all available corrections & measurements incorporated into QL. So, for me, either QL or the OBT hypothesis or both don't work in most cases.

The Optimal Charge Weight (OCW) hypothesis, however, has proven extremely effective for me.

I have a new pound of 760 now, so I may re-work the load to check on myself. Thanks!

I finally had a chance to fire up QL and check your numbers. I think I see what you mean. Even if I crank the temp way up, I still cant get 3600fps without messing with the burning rate. And if I do that, pressures go quite high. I have a 24in 243 and some 414 and 760, but not any 70gr bullets so I cant duplicate your load, but here are some more thoughts, FWIW.

If I run QL using 55gr for the case volume, and 100F barrel temp, I get a barrel time of 1.021, which is right at a 24in barrel OBT. But QL only predicts 3522fps at 60K. I think I will stay with my original guess that you are benefiting by the so called jump.

In my experience, Nosler data is b far the best. I overlooked that you said your results matched Nosler when I read you post earlier. Having said that, I wouldnt be too anxious to throw out that load. But I would be careful with it in the summer.

Since you will be experimenting some more, how would you feel about velocity checking loads at 46.5gr, 46.7....47.7? I would be curious to know if you see a jump. Some load combinations/barrels do it more than others. When I take data every ..2, I only take one velocity reading at each load. Taking data every .2gr makes up for not checking each load increment several times.

Only loaded 3 rounds with the new pound today. This evening's work (on the 243) was previously planned to be w/100 grainers and H1000. What I found, however, was that my 3 charges of 760 (45.5, 46.5, and my previous 47.5 grains) are showing me something different on this powder lot. The 47.5 grain charge, upon careful brass inspection, shows a slight ejector mark on it. Clearly too much pressure. So, this lot appears to be faster than my last.

Another thing I note in QL: The burn characteristics are notably different between H414 and W760. This is very odd to me since those powders are identical and come off the same manufacturing line in Florida.

I only went in 1/2-grain increments for today's work with H1000, but comparing those against QL, I think I can see some of the 'jumps' you describe. I can adjust the Ba to match my velocities, but what I find is that QL's predictions alternate between being slightly (as in just a very few fps) above and slightly below measured velocity. Maybe you mean bigger jumps than this? Anyway, I've settled on an average Ba which tracks about the middle of the jumps I see.

I was able to confirm something with this pound of H1000 that I thought I had discovered previously: Hodgdon's listed max charge (online and in their manuals) is surprisingly low in terms of both pressure and speed. That ends up making me happy in this case, though, because I can get above 3,000 ft/sec reliably with 100-grain bullets while staying a few thousand psi under max pressure!

Forgot to say that, as before, the OBT table is telling me I'm not on an accuracy node, but I definitely am. Oh, well. It's an interesting hypothesis. It just doesn't prove out for me in real life.

Thanks for posting your results. Before QL and OBT I briefly attempted to develop a 243 recipe, but could see that beating Rem 100gr Corelokts from the local Walmart wasnt going to be easy. So I bought a stack of green/yellow boxes and moved on to other cartridges not so readily available. I double checked and actually I do have 300+ Nosler 70gr BTs that need a load. So I am more interested in your results than I originally thought. Have never tried H1000 either.....

Regarding OBT usefulness - I havent used it for all 33 of the ctgs I load for, but for the several I have used it on, it works like a charm. I had some trouble at first but now can home in on a OBT rather quickly, which is good considering the shortage of reloading components.

But my satisfaction with QL/OBT may be due to my perspective. I still recall working up loads using early edition reload manuals and scattered magazine articles, long before forums existed to hand out tried and true recipes (e.g. the so called OCW). I have worn out barrels developing the perfect load. And guess what? The loads I developed in those days line up with OBTs.

I am also an engineer familiar with calculations ranging from how long until we get there, to how high can pressure go before a nuclear reactor vessel explodes. IMO any calculation that gets within a few percent of reality is very good indeed. So my hat is off to the authors of QL and OBT theory.

As is mine. It's always possible that I'm expecting too much or something. An OCW work-up for me ends up using few or no more components than trying to get at an OBT node and then doing the verifications/tweaks (since the predicted nodes appear to differ for me from what I observe).

However, I can see potential utility in using the OBT calcs when I open a new can of powder. One might suppose that, whatever the barrel time of my accurate loads, I can simply load a very few cartridges with the new container of powder, chrono them, make any pertinent adjustments to QL, and then go to the same barrel time as was predicted with the previous powder lot. That's actually in defiance of the OCW concept, it's still something I'd like to try going forward.

I've enjoyed this exchange, and look forward to updating my own experiences and hearing of yours if you try out some of your 70-grain .243s. Cheers!

I am going to pick on the OCW theory and method for a moment. I have held off because the theory originator is a good guy. But a few things really need said.

First off, the theory, in its extreme, supposes that there is some magical charge weight that somehow works in any rifle regardless of barrel length, powder lot, temperature, etc. The theory has some merit in that the collective experience of handloaders has revealed a number of loads where the planets align, so to speak. But it is a leap in logic to say that the charge weight has some magic property. If that were true, then one could substitute 40grs of 4064 for 40grs of 4350 and still get the same results. And we all know that wont work. What actually happens, and I think DN understands this, is that at the so called OCW, the load becomes tolerant of MINOR variations in the other variables.

The OCW method - This method supposes that a round robin sequence of four 3 or 5 shot groups is enough to identify an OCW. The method has some merit in that using a round robin shooting pattern cancels out some of the variables and is quite efficient for the vast majority of handloaders who must prepare their loads in advance of a trip to the range. But 12 or 20 shots are not statistically significant. One needs hundreds if not thousands of rounds to truly identify and confirm an OCW. The part that is hidden behind the curtain is that DN really isnt all that experienced in handloading, and the OCWs he provides were not identified using his OCW method. As was said earlier, they are well known loads that have been evolved out of the collective handloader experience. They were handed down to him by others. If you dont believe me, start with a cartridge that has no published data and see how long it takes you to narrow down the right powder and the right charge weight (without using QL).

I don't understand some of your premise(s).

Firstly, I agree that there's nothing magical about a weight alone, such that it would cross from one powder to another. There is no such claim associated with the OCW concept. I agree that the whole premise is that there's a charge weight of a given powder/bullet-weight combination which is tolerant of minor variations in things. That's the whole and only premise of the OCW concept that I know of.

If we're going to devolve into arguing the statistical significance of 12 - 20 shots (BTW, I disagree with your assertion of insignificance. Comparatively low confidence interval perhaps, but that's very different from 'insignificant'), then we must also argue about the significant errors inherent in using QuickLOAD for attempts at predicting OBTs, and perhaps even the OBTs themselves. Hundreds if not thousands of rounds would have to be fired to verify the QL/OBT predictions, according to your reasoning. But neither one of us, using either method, actually does that, do we?

Dan doesn't 'provide' OCWs that I know of? He has said that he used to have a list/database/whatever of loads developed through that process on his site, but that's been gone a while now. The loads I've 'developed' using the method he describes, for example, haven't been handed to me by anyone. I do use published data to get me in the ballpark of a starting point, but frankly a bit of that same thing can be used to get someone in the ballpark for a completely new wildcat cartridge. The OCWs are also very clearly useful in actual practice and have been far more resource-efficient than using QL and OBT stuff in my experience thus far.

I've heard it said that some (many?) get extremely good accuracy predictions by using the OBT hypothesis in conjunction with QL. I just haven't had that experience in any of my guns thus far, despite thorough adjustment of all variables in QL. I still like QL, but I don't try to use it to predict accurate loads because my experience has shown me that it's a poor tool indeed for that purpose.

Perhaps the most important thing for an engineer to remember, as I'm sure you've experienced countless times yourself, is to let observation drive models and predictions, rather than the other way around. Me, I gave up engineering during college in order to stick with agriculture.

I first discovered QL and OBT when searching for an explanation for anomalies I had observed in my own data. Since then, I have expended thousands of rounds confirming the validity of the OBT theory and QL I am well aware of their strengths and weakness. I am also well versed in statistics and I stand by my previous appraisal of the OCW method. IMO, if your OCWs do not line up with OBTs, then either you haven't really found an OCW, or you don't know how to use QL/OBT. I suggest you do your homework, expend a few thousand rounds and then come back and lets talk. OBTW, I go through a few thousand per year. Good day.

Just noticed that QL V.3.4 sets the .243 "Weighting Factor" at .65. That is too high and obviously in error. It should be .5 or less. If you change the WF to .5 or even .4, you will get velocities and pressures more in line with your experience, and loading manuals.