Gordons reloading tool

[hounddawg]

I know a couple of guys on the forum have been using it. I downloaded it and playing with it today.

Loaded in some of my known loads and it seems to be pretty accurate. How accurate are you guys finding it? I have a couple of pounds of Leverevolution and factory load data is scarce in general for that powder and non existent for a 6BR. Ran some numbers though and it looks like a great powder for 6BR other than fill rate is only mid 80%'s when I stay below Pmax - 15%

[Unclenick]

CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

I've used both QuickLOAD (for about twenty years) and more recently GRT and found they are sometimes about spot on and other times can miss by several percent. In a fairly technical discussion on another forum, an interesting case is made for the limit of velocity prediction accuracy being in the 1%-2% range by the Mayer-Hart system, which is an analytical solution. The point was made that attempts to allow for more precise adjustments of factors than that older system allows for have actually made predictions of velocity less precise. I've seen them miss by over 5% in the two software packages mentioned, which provide iterative numerical solutions. It turns out the cumulative error possible with all the available variables can be less accurate than some general rules of behavior. GRT is soliciting user input of Pressure Trace data to adjust its models and powder data to close in on more accurate solutions, and only time will tell how close it can get.

Here is a paper about the Mayer-Hart system with derrivations and here is a Mayer-Hart calculator. You still need some technical information about the powder to use it. Vihtavuori publishes their data, which is why their powders' values are listed for use with the calculator. You can extract some of that information from QuickLOAD's vivacity data and from GRT's powder data for other powders, but there is some effort involved.

Anyway, the bottom line is probably that if you take a QuickLOAD or GRT maximum load and knock it down 10%, it should be good enough to try, but before I did that, I would run the powder model against some published loads using it first to see if you can spot a trend for pressure or velocity to be low or high and adjust your expectations of accuracy accordingly.

[hounddawg]

thanks Nick, that was exactly the type of info I was looking for. The main issue is there is very little info out there on Leverevolution. I ran the simulation using the published 30 -30 Win data Hogdon has out there and the Gordons data came close to matching Hogdon's . I picked up 2 pounds of this stuff last winter becasue some of the guys over at 6.5 Grendel forums were getting decent results, all boot leg stuff though. I may try some of it depending on how long the shortages last and how desperate I get lol

[Shadow9mm]

I tried it, the number did not match up with some of my known results. I'm leaving it alone.

[hounddawg]

well it came pretty close to matching the results from my last range session, not perfect but close

6Br Norma
26 inch barrel 8 twist
CCI 400 primers
IMR 8208
Nosler 107 CC bullets seated .030 off touch
50 F with a 5 to 7 MPH wind directly in my face

here are three of my five round test groups, averaged FPS and Gordons simulation

26.0 gns actual 2512 FPS Gordons 2508 FPS
26.3 gns actual 2536 FPS Gordons 2534 FPS
26.5 gns actual 2561 FPS Gordons 2551 FPS

Not saying it is perfect, but it seems to have 8208 in the 6BR pretty much nailed

edit-

At the moment I am more interested in playing with the Barrel Time and Optimal Barrel Time aspect of it for load development than anything else. I have loaded up 40 test rounds for Fridays session with different brands of primers. I chose 26.4 gns which Gordons predicts 2543 FPS and being within .0082 ms of optimal barrel time.

Both the 26.3 and 26.5 loads had nice bughole .4 MOA five round groups in some iffy wind conditions. Velocity consistency was ok , but could have been better. Hence the primer test. I am hoping that 26.4 will perform really well and give me that plus or minus .1 gn buffer I like

[RC20]

I had to read Unclenicks post to figure out the so called tool was a reloading software calculator .

[hounddawg]

sorry, forget that people cannot read my mind any better than I can read theirs

I checked a few of my old load tests against the OBT (optimum barrel time) calculator and son of a gun if it did not match up pretty close to what the best groups were on paper. If for nothing else that made it worth the download. I plan on trying a few new powder/bullet combos just to see what happens

[tangolima]

I have been patreon to GRT for a year or so. The tool is pretty good. Rifle is better than pistol. More discrepancy when the load is light. Their cylinder gap / gas port model is pretty cool. Powder library is a bit light, but it is getting better. There are a few ways to work around it. I like their custom ladder setting too.

-TL

Sent from my SM-N960U using Tapatalk

[FrankenMauser]

I keep up with GRT on a daily basis.
There is a lot of development going on and it may turn into a very useful tool at some point.
But, right now, it is still a Beta - arguably an Alpha.

Development aside, there is one very important thing to keep in mind about GRT:
Gordon has established certain pressure levels that he believes each cartridge should operate at. In most cases, this is band of pressure from CIP or SAAMI MAP for the cartridge, and down about 8-10%. There are some exceptions, but most adhere to that.
This is what all of the powder models are built around, and all data outside of this pressure band is eliminated and/or ignored.

The problem with this is that Gordon and GRT do no support subsonic loads for almost anything that isn't already subsonic (like 147+ gr 9mm, or normal .45 Auto). If you want to load subsonic .300 Blackout, for example, GRT gives you errors, because Gordon does not believe that subsonic loads are viable. He doesn't understand the purpose or application. Therefore, he doesn't want to spend the time to develop low pressure specific cartridge files, or allow the tool to work with wide pressure band powder models. (Like subsonic to supersonic .300 Blk.)

Basically, if Gordon doesn't believe in it, you don't get that functionality or data set.

Those of you that don't care about the example, .300 Blackout, probably don't see that as a problem, but I have seen discussions about this being applied to *many* cartridges where it will be a real point of argument or decision for some people. (And Gordon and his lackeys actively shooting people down for considering a reduced pressure/reduced velocity load for extremely common cartridges.)
You want some low pressure plinking loads for .44 Mag? You're out of luck.
Want some reduced velocity .30-30 for your niece to hunt with? Tough cookies. If it's outside the pressure band, Gordon doesn't support it.

Sometimes, Charlie will swoop in and try to tell someone how to force the program to do it by using the Optimum Barrel Time tool. But, even then, there are a huge number of disclaimers, it is a very complicated process, and you're intentionally force-feeding the program bad data in order to hamfist your way into a ballpark workaround.


Just keep in mind that GRT is not a finished tool, and that it is being developed by a person that is extremely opinionated about how each and every cartridge is supposed to be used -- with a squad of enforcers waiting in the wings to jump on anyone that questions it or tries to use it in a realistic manner that isn't exactly what they envisioned.
If your opinion and application do not align, GRT may be useless to you.
And if you speak up about it, the enforcers will dog-pile on you to stop the Wrongthink. (By submission or forced re-education.)

[tangolima]

I agree that folks over at GRT tend to have this sort condescending attitude, so I try not to getting into discussion with them if I don't have to. I pay real money to use microsoft windows. I don't spend much time talking to the company for features I like or don't. I get to use GRT almost for free. So no complaint.

I concur with Franken's comments on light loads. I shoot lighter loads, but I still fine the tool quite useful. It gives me indication of safe zones to work up my own load. Some of the rifle light loads have been very close to the simulation results. Pistol light loads tend to be more off.

I remember there was a gentleman from France trying to analyze his super light 30-30 load with GRT. It was way off. But his load was crazy light, so light that I wouldn't want to fire it myself. He ended up using faster powder if I remember correctly.

-TL

Sent from my SM-N960U using Tapatalk

[hounddawg]

Well it impressed me enough that now I have a copy of Quickload on order. I tried some of the Leverevolution loads today. Velocity was lower 200 FPS than what Gordons predicted but everything went bang and not boom. Got the smallest groups I have ever consistently seen with that Grendel but I do need to hit a higher node if I plan on shooting it in tactical rifle matches @ 800 yards. 2200 FPS was the highest I could hit with what I had worked up but had no ejector swipes or other pressure signs. Rifle cycled fine. I figure the quickload will have a larger and more accurate database.

I purchased several odd powders at the beginning of this mess and have my doubts if I will ever see my old favorites like H4350 and Varget back on the shelves regularly and want to make sure I can do with what I have and can get ahold of