Quickload Newbie with Questions

[daved]

After reading a good bit about Quickload and thinking it would be useful in reducing the time spent in load development, I invested in a copy (plus Windows and VMWare Fusion) and set about developing a 6.5 CM load following a procedure I had noted on this forum: 1) enter all user configurable cartridge data (COAL, case capacity, case length, actual bullet length) 2) identify an OBT node in QL, 3) load several test cartridges 1-2% less than that for the node, 4) chrono the test loads and then 5) adjust the Ba in QL so that the projected MV and actual MV coincide. Once this was done however, I found that there were no usable OBTs - one was over max and the other yielded a velocity and fill % much less than ideal. Additionally, nodes that I had previously identified using a standard OCW procedure were nowhere near the nodes identified by OBT in the tuned QL. I've since repeated everything and get the same results. So what up? Is this something that occasionally happens with a given cartridge/bullet/powder selection? Or is there something in my process that's lacking. FWIW, I've noted that the configuration I was testing (Berger 140Hybrid/H4350/Hornady cases) have historically given much higher velocities (90-100 fps) in my rifle than others seem to achieve with similar seating depths and powder charges in theirs.

Thanks for any input---

Dave

 

[Bart B.]

I chatted a year or so ago with Quickload's rep about their software. His first few words were to the tune of "don't expect our data to be duplicated in your stuff."

Our component lots and barrels plus how they're held when fired are not what Quickload has. They're typical and general and useful to see trends. Nothing exact is guaranteed.

 

[memilanuk]

Once this was done however, I found that there were no usable OBTs - one was over max and the other yielded a velocity and fill % much less than ideal.
...
Additionally, nodes that I had previously identified using a standard OCW procedure were nowhere near the nodes identified by OBT in the tuned QL.

I had pretty much exactly the same experience with QL trying to identify OBT nodes for a .308 Win with 200 Hybrids and Varget or H4895 - the nodes were either just a bit too fast, and brass life was nil, or they were too slow (in my opinion) for competitive use. Found that the 'sweet spots' that most people end up running that combination at is almost exactly half-ways between the nodes indicated by OBT. I did talk to someone who mentioned that there are 'intermediate' nodes, where you may indeed find a (very) accurate load... but the tune window may be very tight compared to a full OBT node. That pretty much corresponds with my experience thus far with the 200 Hybrids and 200.20X bullets - there is a node (or nodes) in between what would be considered the full OBT nodes... but the tolerance for powder / seating depth variance is a lot less than I'm used to with OBT nodes.

HTH,

Monte

 

[brantfredrickson]

Due to unmeasurable variances in powder burn rate, chambers, brass, barrels, and bullet jackets, my experience is the best Quickload has done for me is identify a low node and a high node. And I make sure my load development passes thought those two points. For instance Quickload says I have a node at 41.2 and 43.7 so my load development will run from 40.2 to 44.7 in .5 grain increments. I'm unlucky at coming close to the Quickload node. Some are more lucky!

 

[dcali]

In my view, quickload is a substitute for a loading manual, not for load development.

 

[Ned Ludd]

In terms of "hitting" OBT Nodes, barrel length with respect to bullet weight and expected velocity can be key for some cartridges. In Monte's example above, the 200 Hybrid bullet is one for which hitting the next higher OBT Node is not realistic, even out of 30"-32" barrels. My 200.20X load in a 30" barrel is giving about 2660 fps with H4895. To hit OBT Node 4 (1.3684 ms) would require almost 2740 fps and a pressure approaching 67k psi, so I (and many others) choose not to load that hot.

However, there is a very good accuracy node for 30"-32" barreled F-TR rifles that will generally fall somewhere in the 2630-2680 fps range with Varget or H4895. This node does not correspond to an OBT Node, but nonetheless is still an accuracy node. My perception has always been that there are more accuracy nodes than the just the OBT Nodes. In other words, OBT Nodes represent some sub-fraction of all accuracy nodes for a given rifle/load. My reason for believing this is that I have shot a number of ladder tests that covered a wide enough charge weight range for there to be more than one apparent node. In most cases, the OBT Node will be one of the nodes observed, but the other(s) do not correspond to OBT Nodes. For that reason, I will always check with Quickload after calibrating it to that specific rifle/load to see if I can hit an OBT Node first, but if not, I'll go out and shoot a coarse increment charge weight test series to find the accuracy node(s) I can safely reach.

If you can't quite reach the next higher OBT Node, and the one below is way too slow, the only real downside to carrying out a typical ladder or OCW test is that you lose the advantage of Quickload's barrel time predictions. Those can be an advantage in terms of load development largely because they allow you to quickly and easily adjust your load and barrel time according to an outside standard (i.e. - the OBT Table values), However, lacking the use of barrel time predictions doesn't preclude the use of standard load development approaches to target non-OBT accuracy nodes

 

[mtngun]

2) identify an OBT node in QL, .... 5) adjust the Ba in QL so that the projected MV and actual MV coincide.

1) I personally don't adjust Ba. There are many variables that can cause the projected MV to differ from the actual MV and I accept that as a limitation of computer modeling. 90% of the time QL is usefully accurate at predicting velocities.

2) OBT is junk science. Yes, nodes exist but the math is messy and hardware dependent. There is no simple universal formula for predicting barrel nodes -- it will depend on the barrel, not to mention the action, bedding, etc.. Refer to Boatright or Vaughn if you want to understand the theory. For the average guy it boils down to trial and error, or ladder testing if you prefer.

I am quite fond of Quickload, for predicting likely powders, charges, and velocities in applications where there is little or no pressure tested data. I do not rely on QL for optimization beyond narrowing down the list of powders likely to succeed. QL cannot, for example, predict how well a particular powder will burn in a particular load. I do not expect QL to predict the actual velocity correctly every time, though it often does. If good piezo data is available, or even decent strain gage data, that will carry more weight in my book than QL.

Even pressure tested data from different sources will sometimes differ noticeably. This is the nature of ballistics and instrumentation.

 

[savagedasher]

1) I personally don't adjust Ba. There are many variables that can cause the projected MV to differ from the actual MV and I accept that as a limitation of computer modeling. 90% of the time QL is usefully accurate at predicting velocities.

2) OBT is junk science. Yes, nodes exist but the math is messy and hardware dependent. There is no simple universal formula for predicting barrel nodes -- it will depend on the barrel, not to mention the action, bedding, etc.. Refer to Boatright or Vaughn if you want to understand the theory. For the average guy it boils down to trial and error, or ladder testing if you prefer.

I am quite fond of Quickload, for predicting likely powders, charges, and velocities in applications where there is little or no pressure tested data. I do not rely on QL for optimization beyond narrowing down the list of powders likely to succeed. QL cannot, for example, predict how well a particular powder will burn in a particular load. I do not expect QL to predict the actual velocity correctly every time, though it often does. If good piezo data is available, or even decent strain gage data, that will carry more weight in my book than QL.

Even pressure tested data from different sources will sometimes differ noticeably. This is the nature of ballistics and instrumentation.

Well said
I have used it for 15 years Yes it is a reloading tool . Nothin more
We do agree on OBT Larry

 

[Ned Ludd]

You think that was well-said, Larry? I think it shows a great lack of understanding of how Quickload works. The burn rate factor, Ba, was specifically designed as an adjustable factor to account for varying burn rate of a specific powder in different chamber dimensions, combustion temperatures, and bullet masses. Not to use it for adjustment precludes the major benefit of using the program. If you don't adjust the Ba, your predictions will be mediocre at best, possibly even unsafe.

As far as OBT Theory, I've shot better scores than many a person that could give me lots of reasons why the proposed OBT mechanism couldn't possibly be true. I don't particularly care whether the explanation is correct, as long as it works for load development predictions. In my hands it works very well indeed. In the past before I used Quickload or was even aware of OBT Theory, I worked up several different optimized loads in different rifles that shot all extremely well. I later determined every one of those loads corresponded to a predicted OBT Node. Since that time, I've used it almost exclusively for load development for F-TR rifles and enjoyed a reasonable amount of success with the loads developed. If anyone wishes to believe that is mere coincidence, they are certainly welcome to do so.

 

[Bart B.]

OBT is junk science. Yes, nodes exist but the math is messy and hardware dependent.

The speed of sound OBT used for that pressure bulge to move in barrel steel ain't what mechanical engineers use for vibration analysis and finite element metal modeling. I've belled rifle muzzles out with cleaning rod rubbing to greater diameters than OBT calculations predict and no degradation of accuracy.

 

[CharlieNC]

OBT and QL have worked well most of the time for my applications. However OBT is based on a traverse shock wave, whereas the more classical "barrel whipping" harmonics may have more impact based on barrel diameter, etc. This site has referenced a number of good sources where this can be visualized (varmintal is nice). While the engineering is too complex for most of us to compute on our home pc, even the simpler tools like OBT and QL provide a useful foundation from which to think and optimize load development methods such as ladders and ocw; and provide a good starting point to refine the node vs a blank sheet.

 

[daved]

Wow - lot of info there and divergent opinion. Thanks for the comments.

Other than the problem with nodes I mentioned in the OP, my other problem is that pressure data from the tuned QL does not jibe with my own pressure testing. While QL shows loads in the 42 grain range (H4350/Berger 140TH) as max/dangerous, I've pressure tested to 43.5 with no signs of pressure other than a progressive slight flattening of the primer edges. Even at 43.5 (my personal limit) the edges still have a radius. The failure to give a usable OBT node can be overcome by OCW testing but if the pressure data (which directly relates to MV) data is suspect, all of the QL data is questionable. Any thoughts in this regard?

Thanks again--

Dave

 

[CharlieNC]

Wow - lot of info there and divergent opinion. Thanks for the comments.

Other than the problem with nodes I mentioned in the OP, my other problem is that pressure data from the tuned QL does not jibe with my own pressure testing. While QL shows loads in the 42 grain range (H4350/Berger 140TH) as max/dangerous, I've pressure tested to 43.5 with no signs of pressure other than a progressive slight flattening of the primer edges. Even at 43.5 (my personal limit) the edges still have a radius. The failure to give a usable OBT node can be overcome by OCW testing but if the pressure data (which directly relates to MV) data is suspect, all of the QL data is questionable. Any thoughts in this regard?

Thanks again--

Dave

Dave the calculated pressure warning is based on the sammi spec, which may or may not reflect a dangerous condition in a specific firearm / cartridge combination. When working up a load carefully I have short throat 308 which displays pressure problems at lower than expected charges, while I push the limit in others. Work up charges safely, do not accept arbitrary recommendations.

 

[Bart B.]

I have fired 7.62 NATO MIL SPEC proof loads in converted Garands. 68K cup, 81K psi; peak pressure numbers. Showed some fired proof load cases to several people whose comments after inspecting case heads and slightly flattened primer edges ranged from "looks OK and some of mine look that way" to "maximum load or a bit more but still safe." Showed them the MIL SPEC data sheets listing the load used and its peak pressure spec numbers. All said the military data wasn't correct.

 

[memilanuk]

My understanding was that by the time you start seeing traditional pressure signs such as deformed (flattened) primers, ejector wipe, etc.... you've done sailed right on past 'safe' and are probably closer to the 70-80k range.

 

[daved]

My understanding was that by the time you start seeing traditional pressure signs such as deformed (flattened) primers, ejector wipe, etc.... you've done sailed right on past 'safe' and are probably closer to the 70-80k range.

That leads to the question - can you assume that if there are none of the traditional pressure signs, whatever the actual pressure, it is "safe"? My problem remains that QL data seems to be unreliable for load development = OBTs are not identified in useful velocity ranges, and those in the useful range are considered by the program to be unsafe. What do you believe?

 

[Ned Ludd]

Daved - as I mentioned previously, if you want to hit a QL-predicted OBT Node with certain weight bullets, you need a specific length barrel. The OBT data are plenty reliable, but they are what they are. Your rifle has to be set up correctly in terms of barrel length and chamber specs in order to hit a given velocity at safe operating pressure. That is not any fault of or issue with Quickload or the OBT Method, but rather with the setup you're trying to make work. It's the square peg round hole thing. Too short of a barrel for a given bullet weight and you will be forced to go over pressure, at least according to the parameters predicted by the program (I typically use SAAMI). If you realize this before having a new build done or a rebarrel, you can adjust barrel length for the bullet you want to use. If not, there are only two choices, find a lower node (not necessarily the next lower OBT Node, which will likely be way too slow), or load them hot.

In my hands, standard Lapua .308 brass primer pockets will withstand loads predicted by QL to be running at 60-61K psi reasonably well (i.e. >5 firings, 8-10 may be realistic). Running loads right at the predicted MAX of 62K psi (SAAMI) will net you less than 5 firings. In contrast, Lapua .308 Palma brass has a lot more metal in the casehead and therefore stronger primer pockets. I know a number of people running 200 Hybrid loads at QL-predicted of pressures of 63-64K, or even slightly higher, and still getting 5-10 firings on their brass. So how "hot" you can run a load depends in part on the brass you're using.

As I also mentioned earlier, my 200.20X load in a 30" barrel would require about 2740 fps and a predicted pressure of around 67K psi to reach OBT Node 4. Regardless of what some of the pressure "experts" here seem to be recommending, I'm simply not doing that. You can decide for yourself how much higher you would have to go and whether you think it's wise. That's about all I can tell you except that you really don't want to be the guy at the range with the eyepatch pulling his trigger with a hook. Nor do you want to be the guy wearing a burlap sack because he spent all his money replacing brass after only one or two firings.

If you decide it's not worth it to try and reach the faster Node, simply carry out a standard OCW or ladder test in the charge weight region below and up to what you are treating as MAX, and you will likely find other accuracy nodes that will give you better velocity than the next lower OBT Node. About 1.5 - 2.0 gr window ought to be wide enough to find what you're looking for.

 

[CharlieNC]

That leads to the question - can you assume that if there are none of the traditional pressure signs, whatever the actual pressure, it is "safe"? My problem remains that QL data seems to be unreliable for load development = OBTs are not identified in useful velocity ranges, and those in the useful range are considered by the program to be unsafe. What do you believe?

I would be shocked if you did not find nodes, either by QL or ladder testing, that are within the safe pressure range. Personally I run some hot loads, but none which calculate in excess of sammi spec as I observe undesirable signs at that point. Since you stated your measured velocity is much higher than typically reported, perhaps your chrono is off which is contributing to inaccurate QL tuning for nodes and excess pressure. What are the results using default QL powder spec; do nodes and pressure make more sense in this mode?

 

[savagedasher]

I use QL different then most
Z1 P max Aligment just before or on top of the pressure peak The % of fill amount Or % burned in a given barrel lingth Approx psi with a given case capacity and seating depth . Where it worked best was when regulateing barrel speed on double guns . Larry

 

[dmoran]

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