Does anyone use Quick Load and Pressure Trace together when doing load development? My friend and I use Quick Load and a Labradar to develop loads using Chris Long's barrel time theory and we've had good success finding accurate and consistent loads.
My question is; once Quick Load is adjusted so that the predicted charge weights and velocities match actual field results, are the predicted pressures in Quick Load close to measured pressures using the pressure trace system?

Not necessarily, no. (Yes, I own a PT and a copy of QL)

Sometimes predicted pressures have lined up quite well for me. Other times they're off. Sometimes they're _way_ off.

Even the PT may need 'calibration' on a particular rifle. Probably will, IME. Calibrate it like Harold Vaughn suggests in his book Rifle Accuracy Facts if you can (using a hydraulic system). If you can't do that, use factory ammo as a reference point, depending upon how well your rifle & speeds match with factory test numbers. For example, my Creedmoor rifles both shoot/shot Hornady factory ammo very close to advertised speed, and they have/had 24" bbls just like the test barrel. That plus specific pressure data for that lot of ammo allowed me to get a good reference for the PT on that rifle.

DO NOT rely on QL predictions to keep yourself or your equipment in 1 piece. Rely on published, _pressure-tested_ data (some information came my way in the past that not all published load data was actually pressure tested. I've not been able to verify that either way).

Thanks for the reply. When the two are very different, have you been confident that its QL that was wrong or have you had an instance where it was the pressure trace that needed to be calibrated?

I've also read that some published load data is fired in one barrel to measure velocites, and a different barrel to get pressure. If thats true, I wonder if both barrels actually produce the same pressures?

Where do you source original pressure information for factory loads?

mod7rem, I have been confident QL is wrong even without the PT, but with the PT I have been certain. Note that this is not a knock on QL. The developer is clear and upfront in saying (read the manual) that there are things the program does not and/or cannot model. It is important to remember as individual users that it is only a model and an estimate. When one knows going in that the model does not account for all aspects of every firing instance, one should not expect high-precision results. IOW, it is not surprising that sometimes things are off.

Idaho Shooter, I have not needed to try but a couple of times to get such info, but in those instances I was able to get to the right person in the right place to share. I would not expect to be able to get that kind of info on a regular basis, now that I think of it. I think one might make the assumption that most factory ammo for most mainstream cartridges is loaded relatively close to SAAMI pressures, though. Since this is _not_ a calibration, only a reference point, that seems adequately useful.

Thanks MZ5, thats great info, looks like I might have to look into getting a pressure trace system.

Be prepared to end up with about 5x as many questions after you use it, as you knew you had before. :-)