QuickLoad Trouble / Question - 308WIN

[mjphawk]

Anyone who use quickload get significant differences between the projected muzzle velocity and the observed? I just entered in all of my stats and QL is reflecting a MV that is 100fps slower than what I consistently get out of this load.

Curious if others have had this issue or if this is normal and QL is really just a reference. I have read others getting very accurate results with QL. Not sure if there is a reliable / safe way to "true" QL results but 100fps seems like a lot.

I will post my load but it is only known to be safe in my rifle. (DO NOT USE WITHOUT PROPER WORK-UP):
Cartridge: 308 WIN, Lapua Brass, case capacity 56.2gr H2O
Bullet: 175gr SMK
Powder: 44.3gr Varget
Length: 2.8673" COAL, 0.0012" from lands
Barrel: 24" factory barrel
Temp: 75-degrees
QL is telling me that's 2,640fps @ 55,253psi. Actual MV (measured on Magneto Speed) is 2,750+fps

[bigedp51]

With Quickload you adjust the burn rate in Quickload until it matches your chronograph velocity.

There are far too many variables with firearms and reloading components for Quickload to give more than guesstimates until you adjust case capacity and actual velocity.

Adjusting the Powder Burn rate Factor and the Bullet Weight to Help Match QL to Range Chronograph Data:
http://www.the-long-family.com/Tuning%20QL%20to%20achieve%20best%20results.pdf

[mjphawk]

Thank you. Figured there was something out there but was having a hard time finding it.


Sent from my iPhone using Tapatalk

[Clark]

This may be crude, but I have been operating QL since at least back to 2000, 17 years ago.
https://groups.google.com/forum/?hl=en#!searchin/rec.guns/$20rec.guns$20clark$20magnuson$20quickload/rec.guns/m6hihXtnyM0/oR0IUA4YDYUJ

My jug of Varget QL predictions match the chrono perfectly.
But my jug of H4350 did not.
I found if a entered 4% less powder into QL the velocities matched.
Then when I switched to another cartridge using that same jug, if I entered 4% less powder the velocities matched then too.
So I never changes any constants in the QL library, I just characterized my jugs of powder and handicapped them.

[JASmith]

This may be crude, but I have been operating QL since at least back to 2000, 17 years ago.
https://groups.google.com/forum/?hl=en#!searchin/rec.guns/$20rec.guns$20clark$20magnuson$20quickload/rec.guns/m6hihXtnyM0/oR0IUA4YDYUJ

My jug of Varget QL predictions match the chrono perfectly.
But my jug of H4350 did not.
I found if a entered 4% less powder into QL the velocities matched.
Then when I switched to another cartridge using that same jug, if I entered 4% less powder the velocities matched then too.
So I never changes any constants in the QL library, I just characterized my jugs of powder and handicapped them.
A difference of 100 fps in muzzle velocity between QL and measured, while bothersome to most of us, is not unusual. SAAMI standards focus on safety, hence the pressure gets a detailed discussion. Here is an attempt at interpreting their pressure standard: http://shootersnotes.com/articles/saami-pressure/

Velocity gets a passing mention and, if memory serves, a difference of 100 fps berween one lot and another could be tolerated. The article has a link to the SAAMI standard, so it can be looked up.

Changing the powder weight is smarter and easier than trying to dial the constants unless one has a good understanding of how powder burns.

An alternative to changing the powder weight is to apply a ratio of the actual velocity to the QL prediction. I have learned the slope of the QL curve is very close to what one sees when chronographing a variety of powder weights.

[cowtownup]

One thing about qUickload is that when you select 260 Reminston I assume it's representing a SAAMI chamber specs. If you have a CBI 260 Match chamber with a .160 freebore then qUickload doesn't know that. Unless you know how to use Quickdesign and spec out your chamber for the program. Therefore whenever you enter you OAL for a long freebore chamber and it thinks your using a SAAMI chamber I'm curious about the outputs from QUickLoad. OBviously if you jam you need to add the extra pressure to your end result as stated in the program.
I say all this just as a reminder that the outputs are close at best but also to ask if anybody has any experience with Quickdesign?

[bigedp51]

There are far too many variables between firearms and reloading components for Quickload to give accurate pressure and velocity data without a chronograph. The standard procedure is to adjust the burn rate in Quickload until the Quickload velocity matches your chronograph.

Also Quickload defaults to the lowest case capacity for that cartridge.

Example for the .223/5.56 the case capacity defaults to 28.0 H2O capacity and a Lake City case has 30.6. And the difference between these two cases is 6,000 psi in chamber pressure.

Bottom line, Quickload needs to be tweaked/adjusted to give "ball park" data output and you must have a chronograph and actual case capacity in order to do this.

[ttexastom]

Very well said ed

[FreqRideR]

Did you measure your bullet lengths? I find the bullet lengths in ql to be off from time to time. I always measure and save my actual bullet lengths in a new bullet file. My 168 Sierra MK's were off quite a bit. This will effect chamber pressure.

[darkker]

It can, here is a bit more detail to go along with Ed's excellent reply.

QL is a calculator, nothing more. With a precious few exceptions, NO ONE lists nominal burning rate variations; only a standard caution that you should "Drop loads 10% when switching lots". The few that do list variances, shows that a 10% swing is rather "normal". Since the now defunct A-Squared manual, NO ONE lists lot numbers of anything tested in reloading manuals.
No one lists nominal variances in case capacities... As Ed said, the list of variables is potentially massive.

As far as what QL "knows":
Anything that is produced by Eurenco, is freely given to Hartmut, and he describes those powder remarkably accurately. When it comes to General Dynamics powders, he is rather incomplete, and the sphericals they make (in particular the progressive burning curve powders) he can be dangerously off. Why? It all comes down to standard bomb testing. How many lots did he test? How well does Cartridge X or Y compare to the standard bomb testing capacity?
If he doesn't know what the specs for powder XX are, and he tests 2 different lots in a standard calorie bomb tester; does that accurately describe how the powder acts across all applicable cartridges? Not so much.

As I said, this doesn't make QL a bad thing, just take it for what it is, and understand what it isn't.

[Zero333]

QL is just another tool for handloaders and is to be used no different than a Reloading Manual. And like all Reloading Manuals, it's just a guide.

The only difference between Reloading Manuals and Quickload is that QL is a crazy fun program to play with !!!