victor3ranger
Well-Known Member
I cheat on keeping my notes.
I have a old refrigerator next to my bench so I take a permanent marker and write the load information on it and in it
Gordon’s reloading tool
- Thread starter 338 dude
- Start date
Help Support Long Range Hunting Forum
I have a old refrigerator next to my bench so I take a permanent marker and write the load information on it and in it
Since you have a ton of experience with GRT I figure you would be the one to ask I am having some issues getting accurate velocity data for particular loads. I have measured case capacity, COAL, projectile length/weight, seating depth, barrel length, twist rate and even powder temp while at the range by using an infrared thermometer to measure case temp.
My AR has a .223 Wylde chamber so I put it as a 5.56 chamber and with some projectiles and loads like the 75 Berger VLD I get predictions that are spot on (within 5fps of avg) with what I am seeing in the real world but with Hornady 73 ELD's my predicted velocity is 80fps slower than real world results and despite me pulling the load I am using from the Hornady reloading manual and being .5gr below max load with zero pressure signs (no flattened primers, extractor/ejector marks, easy extraction, good ejection pattern) GRT is telling me that I am at max pressure at the much lower velocity.
I know you can mess with powder factors but since I don't know what I am doing in that respect I don't want to blindly make changes to make the software to fudge it to match what I am seeing especially since I am getting good results that match what I am seeing during testing while using the same powder out of the same jar.
Any suggestions?
I have used it and found the predicted results to be very close to real world results. They do emphasise the importance of taking accurate measurements, particularly the H2O volume of your FIRED cases. You can feed in your own actual results to fine tune the outputs if desired.
As Tommo said, every detail, no matter how small should be measured. I adjust the actual cartridge dimensions in the cartridge file by using my actual chambering reamer dimensions. Since every rifle is different, powder burn rates vary by rifle/cartridge. For this reason, I run the OBT tool and adjust the powder model to my rifle after importing my chrono data. Bullet jump can also be set. There are many other options to refine the output. The GRT that is coming in 2025 will have many new features. I would also suggest logging inot the GRT discord and asking Charlie any questions you have. He is the most knowledgeable man I know with GRT and worked closely with Gordon.
BillLarson
Well-Known Member
Do what you know..... IF.... its working....
I haven't used grt but it's my understanding it's pc software only and there isn't an app for iOS or android. Hopefully somebody else can confirm this
Buckys
Well-Known Member
Ditto. I wanted to use GRT to sanity check pressure. It requires an attention to detail that is hard to convey.
But chatting with Charlie on discord simplified the experience immensely...
ADLEE2
Well-Known Member
Reloading/hand loading requires attention to detail, or the consequences can be fatal. GRT has been good for me. I don't chronograph, so I can't confirm velocity accuracy. GRT does seem to be very close when compared to other manufacturer's load data for muzzle velocity. I've successfully used GRT for load development of subsonic and supersonic target and hunting rounds. I use GRT with combined common sense and research/cross referencing and it has proven to be a very useful and safe tool.
Got it, I thought I read in the thread it being called a App. That's why I interested in finding it. Thank you,
Thanks I will try the Discord.
Ive done the best I can with measuring every variable but I don't have a chamber reamer to measure since I bought my barrel. Its a .223 Wylde chamber so I just input a 5.56 chamber in GRT that lacks the .223 Wylde option.
I just think its odd that I have near perfect results using the same information with one projectile and then wildly different results with another projectile with all else being equal. Especially since my real world results match perfectly with what the reloading manual says I should achieve.
RegionRat
Well-Known Member
Inside the world of internal ballistics, thermodynamics, and tribology, there are things that refuse to behave or be tamed with our math. These topics are like trying to take photos of puppies or squirmy children, they often don't want to sit still and let you take their picture.
Friction, metallurgy, chemistry, etc, all require a sharpened pencil once we get past the undergrad versions. We try to model things with probability and use margins and safety factors... but then along comes Mother Nature and she plays her cruel games... then poof just like that your idea of a standard deviation goes out the window.
I started working in A/D very young with very many others. Quickly after, many of them, even more often than not it was the best ones, found they had no stomach for the chaos in the gun tunnels and test ranges.
They soon quit working the topics like ballistics, energetics, aerodynamics, etc., or in so many words the ones that were full of chaos. Their brains and personalities couldn't take it when the real world refused to follow their keyboards.
When working with internal ballistics models, try to be patient and tenacious. Don't get upset or give up when things don't line up.
Keep an open mind and investigate the parameters that matter. If you stick with it, you will get a view into why things jump off the tracks. YMMV
Best Wishes in the new season and Merry Christmas!
Thanks, I am going to stick with it until I figure it out. I know the program works because it has matched some other testing I have done so there is some unknown (to me) factor that is putting turds in the tapioca, I just have to find it.
Merry Christmas!
