Quickload Newbie with Questions

[daved]

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?

I'm sure I can find nodes by ladder or OCW because I've done the latter for the configuration I'm using in QL. As noted in the OP, QL does not identify any of the nodes (low, med, high) that I have developed using OCW. The only less than max pressure OBT node identified by QL after tuning is at a low MV and case fill %, and much lower than the OCW low node. Many QL users have commented that the nodes identified by OCW/Ladder testing match the OBT nodes in QL. My interest in QL was to have a more efficient way of identifying the same nodes found by OCW. I have not found that to be the case with my common configuration for 6.5 CM - Hornady cases/Berger 140TH/H4350/standard 6.5CM reamer/24" barrel.

MV data came from an Oehler 35P and Labradar which are within 5 fps of each other.

I don't follow using the default QL data - isn't the idea of using the Ba to tune the projections to the unique chamber/grooves/etc of the rifle?

 

[CharlieNC]

Your concept of tuning is correct. But if the resulting pressures seem unreasonable and nodes don't match at all maybe the Ba was tuned too much, resulting in the inaccuracies. I recall reading guidelines in this regard but not the specifics, maybe someone else does. So the question, do the untuned results jive?

 

[CharlieNC]

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View attachment 1013235

Ciphering Jethro?

 

[daved]

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.

OCW and Chrono testing have demonstrated that my rifle configuration can achieve reasonable MV (2775) at presumably normal pressure. However, once "tuned", QL indicates these loads to be way over max pressure. This seems to be a problem with QL not my configuration. Believe me, I'm trying to find a way to use and trust QL but the fact that it won't confirm safe and accurate nodes identified in OCW seems to be a deficiency in the program rather than my rifle.

I just received a new 26" 6.5CM barrel for my AT so I'll have the opportunity to see if the QL projections are any different with this barrel length.

[/QUOTE] 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.[/QUOTE]

As noted above, I've already done the OCW testing. The "experiment" was to see if QL would identify them using the OBT method.

 

[Ned Ludd]

OCW and Chrono testing have demonstrated that my rifle configuration can achieve reasonable MV (2775) at presumably normal pressure. However, once "tuned", QL indicates these loads to be way over max pressure. This seems to be a problem with QL not my configuration. Believe me, I'm trying to find a way to use and trust QL but the fact that it won't confirm safe and accurate nodes identified in OCW seems to be a deficiency in the program rather than my rifle.

I just received a new 26" 6.5CM barrel for my AT so I'll have the opportunity to see if the QL projections are any different with this barrel length.

As noted above, I've already done the OCW testing. The "experiment" was to see if QL would identify them using the OBT method.

What evidence are you using to support the notion that these nodes are actually "safe", meaning, "not overpressure"? In my experience, commonly used brass/primer outputs can be very misleading at times in terms of estimating pressure.

According to Berger's manual, MAX velocity for the 140 HT in a 6.5 Creed is 2634 fps with H4350 and a 24" test barrel. Seating depth (i.e. throat length) can certainly have a big impact on actual load parameters as compared to those found in reloading manuals, which are loaded to mag length and tend to be very conservative, IMO. However, your 2775 fps velocity in a setup you describe as "standard 6.5 CM reamer with a 24" barrel" are almost 150 fps greater than book MAX. That would be enough to make me question just how high the pressure of your load at 2775 fps actually is.

I have found that QL predictions, once the program has been calibrated for a given setup by adjusting Ba until predicted MV exactly matches actual MV, match quite well in terms of velocity to what I experimentally determine for other charge weights. This is certainly not "proof" that the pressure predictions made by QL are inherently "accurate". However, I also generally find brass life correlates quite well to the QL predictions. In other words, loads at or near SAAMI MAX in my hands usually also suffer from poor brass life. For these reasons, I tend to put more faith in QL pressure predictions than commonly-used "pressure signs" in brass.

In any event, in all the time I have been using QL, I have only come across a single case where the program predicted a ridiculously high pressure that clearly was not happening. In that specific case, it is likely that there was an issue with the program's file for that specific powder. So there certainly could be cases where QL isn't giving the correct outputs. However, I have no reason to believe there is anything wrong with the H4350 file data, it's not a powder I use but I know a number of people that do and their QL outputs for loads with H4350 don't show anything abnormal.

Edited to add: I just looked up commercial ammunition "box" velocity values for 6.5 Creed and a couple brands using 140 gr bullets list 2710 fps. So your 2775 fps doesn't necessarily seem all that high. This may simp,y be one of those examples where QL isn't giving you the right outputs, as you suggested. I also spoke with a friend that shoots the Creed and he didn't think your load was excessively hot either. His suggestion if you simply can't hit the OBT node with the 140s, switching to the 130 VLDs might be an alternative that would allow you to get a bit more velocity and possibly hit the OBT Node with the lighter bullet. Just a suggestion, anyhow. Good luck with it.

 

[SheepDog]

Figuring the resonance nodes in any given barrel would require entering the barrel length and specific dimensions of the taper on the barrel. The thickness of the barrel wall from breech to muzzle is needed to calculate the amplitude and frequency of the wave. As a barrel tapers the waves become stronger and faster. a straight cylinder bore will have a balanced pressure wave from breech to muzzle and back again. You also need precise measurements of the pressure/time rise to the peak pressure. Without that information the software could only use averages and hope that your gun is close enough to the average to fit.
You will find it easier to believe what is actually happening on your targets and tune your load using that information.

As for an extra 150 fps I have seen that much difference in two 357 magnum revolvers using the same load. There are fast barrels, slow barrels, tight barrels and loose barrels. You can have a fast tight barrel or a fast loose barrel and all at the same loads.