Home Forums Hunting & Shooting Ask The Gunwriters Quick Load Assistance

If anyone has a quick load program, and wouldn't mind assisting me in guestimation of the pressure
of a load, I'd sure appreciate it...

Send me a PM...

Thanks in advance...
seafire


Posted on the wrong forum first, excuse me for the operator error...

Seems they reversed the order of Ask the Gunwriters and the Optics Forum

In my experience, which includes access to a couple of different pressure labs, the pressure predictions of QL are its least reliable aspect.

Yes, but Dali Llama Bob will be by shortly to set the record straight, hopefully.

Oh goody. Am always eager to learn the truth from his posts.

While I have no way of disagreeing with you John, however,I have found the QL program beneficial in the load development process.

This took a great deal of study of internal ballistics then applied to the program.

With the use of QL the velocity entered into the program must be accurate as must be all other variables such as COL, Bullet dimensions, powder charge etc.

A friend and myself have tested various combinations of components in the search for an accurate load. This has been pretty much accomplished, save for double base powders.

Usually a QL load will be in the 0.7 moa range using a platform with no mechanical ills, I have one Tikka Tactical in 300 WM that is a solid 0.4/5 moa performer out to 1000 yards, when I'm having a good day.

The handloading books from the various bullet / powder manufactures are still referenced.

As a test for a club 1000 yard shoot, using my 30-06 Finnlight while still wanting to be within the range of the M1 turret on the 6x42 Leupold, about 33 moa up, I went through QL and external ballistic charts. Anyway, a Berger 155.5gr bullet had the BC and the potential velocity to make 1000 yards with 31 moa on the turret. Entered all variables into the program for a 570mm barrel and the result was 61grs of H-4350 for the velocity predicted. The result was ,in the hunter class, 3 shots in 7+ inches.

QL basically does the math for you.

Axtell,

I didn't say QL wasn't useful. I've been using it since the first version appeared. But it isn't a particularly accurate way to determine pressures--as so many on the Fire assume.

Appreciate the input folks...

But since I don't have any friends who have pressure labs readily available....

am I assuming it will sorta give me a ball park?

The Ruger 77 seems to handle the load quite easily, with no issues.. as does the brass and the primer...

but then again, this is the internet and the campfire...and all.

Is it the program or how one operates the program? I use the calculated pressure, which in turn gives velocity, as reference of one load to the other with varying components or powder burn rate.

Its all about getting (for me) an accurate barrel time, within the the window of safe operating pressure and reasonable velocity.

Here's an example: One of the pieza labs I'm acquainted with had a bullet company contract with them to pressure-test loads for the bullet company's new manual. The bullet company loaded all the ammo with QL-predicted charges, then shipped it to the pressure lab. About 1/3 of the ammo was close to the predicted pressure, about 1/3 was way under pressure, and about 1/3 was way over pressure. So the prediction for your load with have about a 1-in-3 chance of being in the ballpark.

Quick load by design has trouble with absolute pressure - there's no way it can know the burn rate of your lot of powder, or the brisance of your primer lot or how much bigger than SAAMI minimum your chamber is. Note that the exact same problems (and MANY more) plague "published" load data - there is no way either one can be updated for your specifics.

What QL does VERY well is understand the relationship between pressure and velocity. If you set everything correctly (fired case capacity, shot start pressure, weighting factor, all weights and lengths) and then run it, for a charge you've chronoed, and adjust burn rate (Ba) to give you your measured velocity, then the resulting pressure it gives will be VERY close to your actual MAP. Furthermore, you can then adjust the charge weight and both pressure and velocity will be very accurate for other weights as well.

That's all you need to safely develop loads using it, including wildcats and new bullet/powder combinations for which no manufacturer data is available.

No disagreement here. I understand that the Berger manual was produced fro QL........but could be just a rumor.

That's a fact, not a rumor.

This has been my experience with it as well. I haven't used it since the first version, but I've been using it for most of a decade. I enjoy the program, but determination of pressure isn't its strong suit. I use a strain gauge system for that.

That's my view of QL as well. From a usage viewpoint, it's an analytical tool/model and "garbage in = garbage out" applies. Like a lot of analytical models, calibration from empirical data is often needed as well as understanding the sensitivity and role of the parameters that contribute to the model.

This is the key. If you use it without thinking about what you're doing and double checking everything, then it accurately models SOMETHING, that something just doesn't happen to be the thing you've got. You have to look at every single parameter, understand what it does and why, and make sure that it accurately reflects what you've got.

I can't remember the last time I missed a velocity by more than 50 ft/s or a MAP as measured by strain gauge by more than 2 KPSI once all parameters were set correctly. That's without a burn rate adjustment other than blindly taking off 0.06 from Ba for straight walls and 0.03 for things like .375 H&H. With an adjustment based on chrono velocity, the errors on MAP are generally < 1 KPSI. The relationship between velocity/energy and pressure for a given burn profile is just too constant to miss by much. I still use my strain gauge just to be on the safe side, but the reality is it's not needed. QL plus load-to-velocity gives enough accuracy to safely pioneer new bullet/powder combinations and wildcats with no danger. It's certainly less error prone than manufacturer load data.

Once I have characterized a jug of powder in Quickload, it will predict for other cartridges the load with that jug that is the threshold of extractor groove expansion.


It does not work for the threshold of primers falling out the first shot.
It does not work for the threshold of primers piercing.
It does not work for the threshold of extractor groove expansion with Blue Dot in 223.
These are things with out of control variables and so do not have repeatable thresholds.

Hartmut Broemel's Quickload has had a permanent place on my computer for many years. It provides very useful answers for general "What If" questions. Herr Broemel is very careful to make no claim regarding absolute accuracy, but I trust his approximations to be equivalent to actual measurements made with different barrels, primers, powder lots, cases, and other variables. I consider them all to be "indicators" instead of "absolute truth" describing what may happen in my gun.

The instruction book, QL_ENG.PDF, included in the program installation is an excellent tutorial on interior ballistics.

I have been using QL for a number of years and have come to rely on it to some extent, but my method is to enter my own case capacity, OAL, and barrel length and look at pressures and corresponding velocities. I do not care about the charge-velocity predicition. I generally set a limit for pressure with two or three thousand psi as a margin of safety...for example, for a cartridge with a SAAMI pressure limit of 65000 psi, if it says I'll be at 63000 psi at 3100 fps, I make sure I don't exceed 3100 fps. I usually don't fiddle with Ba because I don't believe it has that much effect on the pressure-velocity relationship.

This is a sensible approach. Ba calibrates the velocity and pressure to your powder lot, primer lot, and chamber dimensions. But the pressure vs. velocity relationship is basically fixed for a given burn curve - the harder you push, the faster the bullet goes. So if you find the velocity at the pressure you want, and then load to velocity with a chrono, you will also be loading to pressure. You don't really need to adjust Ba although it never hurts if you like to see the numbers match up.

I use a LabRadar to get velocities, claimed to have a 0.1% error , so 2 or 3 ft/s for most cartridges.

The procedure is to load a moderate charge weight and check true velocity against QL predicted. If the corresponding velocity does not match the predicted I adjust burn rate until it does, up to 10%.

Now if the barrel time is off I will adjust powder charge until I get the barrel time that would indicate a node.