QuickLoad Case Capacity Default Accuracy

[amtx2019]

I recently purchased QuickLoad. I have playing with it a few weeks now and running numbers to compare with data other members have been so helpful to provide. I have been fairly accurate on my numbers but have a LOT of learning to do! I am putting together a 300HAM'R bolt gun that I will be loading for. I have loaded for this caliber a small amount for an AR platforn using Wilson Combats load data. Getting started I measured case capacity of some new unfired brass I had to get a H2O volume. My case showed an average of 29.37 but QuickLoad had a default of 32.2. That's a difference of 2.83 grains which is a lot on such a small case. Has anyone seen this much difference on QuickLoads data or maybe is it just a misprint?? Any thoughts would be grealtly appreciated!

 

[GLShooter]

I've found those numbers off all the time. Go measure different head stamped brass and you'll find that much variation. Plug your numbers in to QL and gave at it. That's one reason we wildcat shooters love it.

Greg

 

[dellet]

A good place to start would be to check the instructions and see if Quickload uses fired or unfired case capacity.

It's a great tool once you understand how it works.

 

[amtx2019]

With such a small case capacity of this cartridge .5 to .7 grains is a huge pressure difference. Definitely worth paying close attention too!

 

[Jager]

Case volume is one of the critical factors dictating what pressure/velocity will be. And, as Greg notes, if you measure different headstamps, you'll find quite a bit of divergence from manufacturer to manufacturer - and sometimes lot to lot.

The default case volume in QuickLoad can never be more than an estimate, since QL has no way of knowing what brass you're using. Anyone using QL with an eye towards understanding what pressures they are running, has to measure a sample set of their own particular cases in order not to get in trouble.

Bullet length is another factor that I've often found incorrect in the QL database. Measure a few from your own box.

Welcome to QL. Like dellet says, it's a great tool.

 

[amtx2019]

I here ya Jager! There is a mountain of information which can be challenging. I have taken published 300 HAM'R load data and run them through QL, with my case capacity data, and find disturbing pressures. Maybe I'm not plugging in the right numbers? Check and recheck right?

 

[std7mag]

I try not to switch back & forth, or mix headstamps for that very reason.

One thing that has surprised me lately was looking up 257 Roberts AI inputs. Max pressure in QL is 51 thousand something. Under 52,000.

 

[olddav]

Measure case volume on fired brass. That will better represent your chamber. If you do not have any fired brass I would leave the default volume in place until I do.

 

[Straightshooter1]

I here ya Jager! There is a mountain of information which can be challenging. I have taken published 300 HAM'R load data and run them through QL, with my case capacity data, and find disturbing pressures. Maybe I'm not plugging in the right numbers? Check and recheck right?

There's definitely a learning curve for using QL. When I fist started using it, I had similar issues and one of the things I was doing was using case volume based on sized cases. QL used fired case volume and QL's calculation are based on fired cases. That may be part of your issue. Also, I'd say QL's calculation is also based on maximum SAAMI case length. If your cases are trimmed quit a bit shorter than the max case length, that's also going to contribute to that difference. Then, like as been mentioned, you can have variances in case wall thicknesses, which can produce a significant difference. These things are what is good to do your own measurements of your brass.

. . . and not mix different head stamps

Then, of course, you're looking as the pressure's shown by QL, you have variance due to things like seating depth as measured by COAL for QL's calculations. And once you have some chrono data along with temperature to help you adjust powder burn rate, you'll have a better idea where you are with pressures.

To answer your OP question . . . I've found the QL's case volume to be pretty close to what I've measure on what I'd call standard fired cases (not thin walled cases, like say some Winchester brass).

 

[amtx2019]

I do have some fired brass and will measure some. Seems like most of the info I can find from another forum is guys are seeing about a grain or less capacity increase after firing.

 

[amtx2019]

Thanks Straightshooter. I will be measuring and proceeding slowly. The 300 HAMR being a low volume case will be pretty sensitive to case capacity and bullet seating depth. But all cartridge reloads should be taken seriously. I appreciate everyones input!

​

 

[Ned Ludd]

As has previously been noted, the case volume you want to use in QL is that measured from fired brass. Although fired brass has contracted ever so slightly from its peak volume during firing, which aids in allowing the cases to be readily extracted, it still has the volume that is closest to the maximum internal case volume when the case has fully expanded to fit the inside of the chamber; i.e. the "pressure cell" volume.

Below is a chart often seen on internet shooting forums that lists some average case volume values for various brands/types of .223 Rem brass, which is the parental case for the 300 HAM'R. As you can see, the listed values are from 28.0 gr to 30.6 gr, or a total range of 2.6 gr. Further, none of them actually match the factory preset value of 28.8 gr used for the .223 Rem case in QL. To be honest, I have no idea how they came up with that specific value, although I'm sure there was a reason they did so.

Although very important, case volume is not the sole factor that determines pressure and velocity with a given powder. Other factors such as case shape, bullet weight, start pressure, and primer selection also factor in to the equation. Initially, I would suggest inputting your actual measured average case [water] volume with all the other pertinent cartridge measurements and temperature, then adjust the burn rate (Ba) until the velocity predicted by QuickLoad exactly matches your measured average velocity. I typically refer to this process as "calibrating" QL to a given setup. Usually, once I have calibrated QL to give the same predicted velocity as the measured average velocity for a given charge weight, the predictions will be fairly accurate within a given charge weight range from that point on. One caveat is that of your have to change the factory preset Ba for a given powder by more than a certain percentage, QL has some suggestions for other things to do besides solely adjusting the Ba. I haven't had to do that in a long time and I don't remember exactly what their alternatives are, but they are listed in the User Guide, so you should be able to find them and read up on it.

 

[amtx2019]

Thanks for your reply Ned Ludd for the information. I guess my biggest issue at this point is not having my new barrel. Kind of getting the cart in front of the pony but it does give me time to play with QuickLoad and get valuable information from knowledgeable folks who have experience with the program. I do have my 6BR and 308 with good data to work with QL and will make me more familiar with it. I'm taking baby steps at this point! No doubt I'll be looking for more advice!!

 

[Dgd6mm]

amtx2019, just to let you know, there is a ton of useful information in the archives from people like Ned Ludd on QL. If you scroll down to the bottom of the page there may either be something useful to you or will lead to something useful. I'm just saying, ton of excellent information on this site provided to us.

 

[amtx2019]

Yes Sir Dg6mm! I read everything I run across and find much to be of great use. Sometimes you can go on mental overload and have to slow it down a bit and proceed at a slower pace. I guess QuickLoad is just another useful reloading tool to add to ones loading arsenal once you apply it properly.