Does QuickLoad include Grendel?

[centerfire]

I shot single shot pressure ladders for every powder. I only tinker with QL, it's not doing anything productive for me. The exception is it's good at predicting case capacity fill % so I can choose potential powders based on that since I don't like compressed loads.

[grayfox]

Many Grendel owners are interested in using Quickload for three main reasons:

1) To figure out what a safe max load
2) Finding an accuracy nodes
3) Finding Maximum Velocity for Hunting and Long Range Shooting

I noticed “centerfire” did something different in calibrating QuickLoad for his gun, he varied the case volume, most people teach varying the burn rate because each lot of powder burns differently, a little faster or a little slower. If your goal is “To figure out what a safe max load“ looking at the Velocity is the key. You can vary the case volume greatly (basically different chamber sizes or Brass Case Brands) or vary how fast the power burns greatly (different lots of the same powder) and still get the same velocity for the max safe load. Very small velocity errors (1%) can be explained away as a function of rounding errors, for example a max load could be 27.333 grains but reported max load 27.3. This velocity will change with different barrel lengths but will be the same on all Grendel rifles of the same barrel lenght using the same powder.
....
You can go out with a small single shot ladder and quickly find your max load for your rifle using a chronograph making sure you stop when you reach the max velocity. (Always check your brass and primers, you could have a short chamber changing the pressure rules.)

This has been an interesting thread for me. however I would also like to offer up some caveats regarding Jimla's post -- I think these should be borne in mind to temper somewhat one's expectations for Grendel performance ala QL vs actuals.

1. If "This velocity will change with different barrel lengths but will be the same on all Grendel rifles of the same barrel length using the same powder" is talking about actual MV then it is not completely accurate. Due to variables like barrel friction, chamber actual dimensions, and twist geometry, as well as lot to lot powder variations, the "same load" across different users will not necessarily generate the same MV. Additionally, since internal friction etc has something to do with max pressure the max safe MV/pressure load can differ across the "same" barrels, yet in different rifles and users' hands.


2. A 1% MV error, which would be typically about 24-27 ft/s, is 2 or more SD levels above what a good nodal MV would have (I look for less than 10 SD), therefore I don't think one should necessarily accept a "1%" variation as ok, especially when looking for an accuracy node. Now to be fair, if this is merely to explain as a guide the neighborhood of MV within which you should be looking, then that's probably ok.


3. "Small shot ladders" of 1 shot per load will suffer from actual MV spreads such that it may indicate a higher or lower MV than the mean for that given powder/lot/load. Meaning if you have a 60 ft/s SD spread then a single shot could be up to -- idk -- 60 to 100 ft/s off from the "true" mean load-MV for that load weight. When you graph these the outliers will show high or low compared to the relatively straight line progression (or a very slow curve) for that powder/load sequence.


4. Since the Grendel's max pressure is lower than where most brass indications occur, many excessive pressure indicators only show up after you have already exceeded Saami max. Also one should be aware that their bolt may have a possible "sharp ejector" that can mark the case bottom even though pressure might be below Saami max.

But like I said, this is an interesting thread and I'm not trying to take away from its value.

[JASmith]

Grayfox has it right!

[Klem]

Just to give a little background about myself, out of University I graduated with BS in Computer Science with minors in physics and mathematics. When I was young I had all the needed education in the three areas (Computer, Physics and Math) necessary to create the QuickLoad tech. So generally I have a good idea on how it works.

Many Grendel owners are interested in using Quickload for three main reasons:

1) To figure out what a safe max load
2) Finding an accuracy nodes
3) Finding Maximum Velocity for Hunting and Long Range Shooting

I noticed “centerfire” did something different in calibrating QuickLoad for his gun, he varied the case volume, most people teach varying the burn rate because each lot of powder burns differently, a little faster or a little slower. If your goal is “To figure out what a safe max load“ looking at the Velocity is the key. You can vary the case volume greatly (basically different chamber sizes or Brass Case Brands) or vary how fast the power burns greatly (different lots of the same powder) and still get the same velocity for the max safe load. Very small velocity errors (1%) can be explained away as a function of rounding errors, for example a max load could be 27.333 grains but reported max load 27.3. This velocity will change with different barrel lengths but will be the same on all Grendel rifles of the same barrel lenght using the same powder.

Since the case volume and powder burn rate are not used at all to calculate the Velocity of the max load, you can used the default setting to get the number.

You can go out with a small single shot ladder and quickly find your max load for your rifle using a chronograph making sure you stop when you reach the max velocity. (Always check your brass and primers, you could have a short chamber changing the pressure rules.)

Jimla,

With respect, QL does not reveal accuracy nodes or max velocities for hunting and long range shooting.

Accuracy nodes are something you can only discover by going to a range and shooting targets, preferably with a chronograph.
Maximum velocity is also something you can only discover shooting your work-up loads at the range with a chronograph.

QL does however predict pressures and velocities for whatever load you want to assemble. You can also use its SAAMI pressure limit as a voluntary max load. It is unlikely the predicted velocity will ever match the actual velocity but it will be near.

I also don't understand what you are saying when you suggest 'case volume' and 'powder burn rate' are not used to calculate velocity. I have QL open on the desktop as I type and varying the case volume sure does change the predicted velocity. You increase the case volume and the velocity drops.

I like QL for doing 'What if's?' with different powders and bullets, to find the most efficient loads for the bullets you want to try.
.

[Fess]

I appreciate this thread too. I had been wondering about the accuracy of Quickload for the Grendel these days. For those of you who weren't following the 6.5 Grendel immediately after its debut, there was an early controversy that sprung up over Quickload predictions. It took a while for powder manufacturers to publish load data, so initially, most of the load information was on sites like this one. Around 2005, as I recall, there were posts that stated that some of the loads commonly being used were dangerously overpressure based upon Quickload. Some predictions were well over 70,000 psi. The usual panic ensued: predictions of kabooms, maimed of Grendel shooters, fire raining down from the heavens, cats and dogs living together, etc.

Bill Alexander, who had performed pressure barrel tests on various loads, stated that Quickload often drastically overestimated chamber pressure for the 6.5 Grendel. It was a long time ago, but the moving-bullet hypothesis sounds about right. Furthermore, Mr. Alexander pointed out that the actual pressures could not possibly be near the predicted ones since Grendel case would definitely show overpressure signs at 70,000+ psi in an AR15.

I knew that changes were made to Quickload to improve its predictive capability and figured that the lack of continual panic posts on this site indicated that those changes largely solved the problem.

[centerfire]

I like QL for doing 'What if's?' with different powders and bullets, to find the most efficient loads for the bullets you want to try.
.

Me too.

[Jimla]

Jimla,

With respect, QL does not reveal accuracy nodes or max velocities for hunting and long range shooting.

Klem,

You need to learn how to use QuickLoad, I can't teach someone with such strong opinions, I gave you my background and you claim I am wrong. Because of this I will not reply to your posts in the future.

Quickload can create a list of velocities for powders "max velocities for hunting and long range shooting"

https://www.youtube.com/watch?v=a3RkvTxW4lE

I used this feature on many calibers and bullets and it is a helpful tool.

Quickload can help find accuracy node

https://www.youtube.com/watch?v=Nyis5rXaZq4&t=21s

I used this feature on many calibers and bullets and it is a helpful tool.

Tiips for other people reading this post who are interested in listening to what I said:

The accuracy node is normally in the range .1 grain of what Quickload provides. Something I found using my understanding of physics, you can also find lesser accuracy nodes if you go in the exact middle of two nodes. The reason why this also this works, is the bullet leaves the barrel at the extreme whip, it is the moment of time that the barrel is not moving because it is changing direction from going up to moving down. The other Accuracy point is when the barrel is perfectly strait. The Half nodes can be useful to find higher velocity node, when normal nodes are too slow to be effective hunting round.

I also had problems finding accuracy nodes on 16" barrels, because they are normally not 16" but a little longer so it does not work. It has work great on 18" 20" and 24" for me.


RL-17 will come up as a great Grendel powder in some bullets. It will only work in Bolt actions, the powder will be still be burning and expanding while going down the gas tube, which is not a good thing. Before using a new recommended quick load powder, do an internet search.

[grayfox]

Jimla,
Like I said, I don't personally use QL so won't speak to any ability of it to generate lists of best hunting or long range MV's. I did however, develop my own OBT based spreadsheet (cost me $$$zero dollars) that identifies accuracy nodes as proposed in the add-on OBT tool-app in the second Youtube.

By the way, from a physics perspective, the OBT theory does not use a barrel whip model, rather it uses the longitudinal/radially-oriented donut-shaped pressure wave that propagates down and back in the barrel at ~18,000 ft/sec (speed of sound in steel). The accuracy node under OBT theory is the timing at which the muzzle tip is radially "quiet," not barrel-whip (or, axially) "quiet" -- bullets exiting at an OBT point will have consistent/equally-dispersed gas flow behind them at exit and thus will tend to launch at a consistent angle from the muzzle. All this comes from the work by Chris Long in his paper, “Shock Wave Theory – Rifle Internal Ballistics, Longitudinal Shock Waves, and Shot Dispersion,” (http://www.the-long-family.com/OBT_paper.htm, Copyright 2003-2004).

As to best long-range hunting or or target MV's I guess I'm old school and rely mostly on what the pros have found, then adjust it as my barrel might need to have it adjusted. Chrony and OBT-Spreadsheet, and reload tools, close at hand.
I could see the value, sure, of QL in what-if or other quasi-experimental load work........ but I do really wonder at why one would choose RL-17 as a powder for the Grrr. That however is another story and I'm not trying to hijack any threads with that comment, if you want to use RL-17 in your Grrrs, fine by me.


edit to add: accuracy nodes are no problem for me in the 16", they do get tougher to find in 12" or so barrels, I don't use those barrels much so maybe it's just lack of run-time.

[JASmith]

I have done a fair bit of work with the Grendel using QuickLoad and RSI Pressure Trace using the TC Encore (a break action single shot rather than a bolt action).

The significant differences between QL-predicted pressures and velocities keep one from more than vaguely/forecasting the velocity when a new powder and bullet combination is used. Changing case volume can indeed get the QL velocity to natch for a particular powder and bullet volume. My tests, however, showed that one cannot expect that this adjusted volume will predict the pressure and velocity for a different powder and bullet.

The limitation also applies to calculating barrel time.

Now, once one has found an accuracy nodes and has calibrated QL parameters to replicate (vice predict) the associated velocity, one can find the next node using, IIRC, the Optimal Barrel Time Theory and adjusting powder weight tp get the new barrel tome.

[Sinclair]

I have done a fair bit of work with the Grendel using QuickLoad and RSI Pressure Trace using the TC Encore (a break action single shot rather than a bolt action).

The significant differences between QL-predicted pressures and velocities keep one from more than vaguely/forecasting the velocity when a new powder and bullet combination is used. Changing case volume can indeed get the QL velocity to natch for a particular powder and bullet volume. My tests, however, showed that one cannot expect that this adjusted volume will predict the pressure and velocity for a different powder and bullet.

The limitation also applies to calculating barrel time.

Now, once one has found an accuracy nodes and has calibrated QL parameters to replicate (vice predict) the associated velocity, one can find the next node using, IIRC, the Optimal Barrel Time Theory and adjusting powder weight tp get the new barrel tome.

This may be a dumb question to most of you, but what does IIRC mean and how does the OBT node value tell you what the MV should be? I have been unable to find any correlation between the node value an the associated accuracy node MV requirement.

Sorry to be so stupid,
Sinclair

P.S. I am a MAC user so QuickLoads is not an option.

[Klem]

Well, this is an interesting topic.

Jimla, you are working on the theory that barrel whip is up and down with nodes where the barrel slows down to change direction (which makes sense to me) and minor nodes when it is straight (presumably moving fastest in the whip...(this does not make sense to me, at least from the speed of the whip perspective). Grayfox. you prefer believing reality is predominantly based on radial whip, based on pressure waves going back and forth. Believing this then discounts the idea the tip of the barrel is spinning in circles. I have always understood whip to be elliptical, with best barrels being those where the ellipse's eccentricity is more vertical than horizontal when the barrel is finally fitted to the action. This, because the whip's eccentricity best-coincides with the ballistic arc. When working up a load the best groups will be those where the bullet exits the barrel at the top of the arc. Different hypotheses for what the barrel is doing to cause what we see on the target.

Putting these ideas aside for a moment I have always been concerned about entering barrel length as a variable in QL. Like handguards, manufacturers often round-up or down the length for marketing simplicity. A Lilja '319' is closer to 18.8" total length than 19", and how do AR barrels with an attached barrel extension compare against bolt gun barrels that do not have this extra length of non-barrel when retailers call it a particular length? Plus different lengths of barrel tenon will give different overall lengths of barrel if you measure the actual length from top to bottom on a bolt gun. Surely barrel length as a variable in the physics of what is occurring has more to do with length from throat forward to muzzle, or case neck forward to the muzzle? These lengths are shorter than the overall length of the metal pipe called a barrel that retailers quote.

I am an advocate of QL but I think it is a simplification of reality, and therefore is a clumsy predictor of reality. Compounded by us when we enter imprecise data...GIGO. I use QL to complement going to the range and shooting targets with a chronograph and Kestrel.

(Jimla, sorry if I have upset you but I don't believe a formal education adds merit to an idea. The merit of an idea should be able to stand on its own regardless of who engineers it).

[FW Conch]

^ Yes ^ In the end, we need to get our faces out of the screen, and shoot the firearm.

[grayfox]

Good morning Klem, I'm not discounting axial, or elliptical, whip, merely pointing out that the OBT approach does not (based on my reading of it) make use of it in its theory. As both you and FW say, get off the duff and go shoot, the target and the chrono are the reality. And, just as QL is a model for predicting, so are OBT and the working-theory equation that Chris developed. Of all the math shooting aids, this one - OBT - has helped me the most.

Sinclair, "IIRC" = "if I recall." look up that url link in my last post for Chris Long, that's where OBT started. The main idea is to find a primer/powder/bullet/coal combo for a caliber that closely matches a "nodal" velocity for your barrel length, it is a bullet's "travel time" down the barrel (so, tied to an exit MV) such that the longitudinal pressure wave is "far away" from the muzzle, ie, back at the breach end.
You don't' need QL to make use of OBT... like I said, I developed a spreadsheet that I use, and others simply use their targets and a chrono to find their nodal MVs.

Those who use QL and are good at it, like Klem, at the same time recognizing it is an approx, my hat's off to them.

[JASmith]

IIRC = If I Recall Correctly

Discussion on using Optimal Barrel Time in Quickload: http://forum.accurateshooter.com/thr...kload.3900903/

One needs to tweak input parameters to get the measured velocity in QuickLoad. Even then, the barrel time depends on the acceleration profile. In other words, a fast powder gets a bunch velocity early, a slow powder adds more velocity later in the trip through the barrel. The barrel time will be different from actual because the tweaks changed things. It, may, however, be close enough to be useful.

The fact that the bullet may actually be moving when the main charge lights complicates the barrel time issurpe even more.

[grayfox]

Definitely agreed on the pressure curve/acceleration profile. and a moving bullet is a new (to me anyway), complicating factor. I've also been pondering what an attached muzzle device does to the longit. wave, plus how/how much does internal friction ("fast" vs "slow" barrels) come into play, plus some other factors. Chris' equation is an empirical one; my adaptation is as well. As a non-QL'er his theory has been useful to me.