What are y’all’s thoughts about Gordon’s Reloading Tool as an assist with load development?
I think it’s a good tool to have, but it’s a tool, not a Bible.
My first experience using it was with a load for a short 16 in 7mm-08. None of the published loads was giving me good accuracy. When I ran them through GRT I found they all were giving me less than 100% burnt propellant (which is not good per all of the online/youtube reloaders who use GRT or other programs). It was due to the short barrel. In regular lengths they did fine. So I crafted a load based on GRT which gave me 90% or more fill capacity with 100% burnt propellant and that load worked great. I didn’t feel comfortable just creating that load and throwing it in the rifle, I did a ladder test for safety/pressure sake, not groups or flat spots. No pressure was noted so I then loaded up my target load and tested.
On the other hand, I created a 7PRC load long before I had GRT. It’s a bit slow, but quite accurate, several 0.5 MOA groups with a lot repeatability on testing. Just for the heck of it recently I plugged my load into GRT and it’s telling me I’ve got only 92% burnt propellant right at 100% fill capacity, and there are much better powders than H1000 for me to use. I don’t really want to go through another load development for that rifle when the one I currently have works so well.
I learned a bit from watching some other Youtube channels.
The creator of GRT passed away in 2021. His widow now owns it, and has said it will never be updated again. There’s a lot of online support from users, but just like everything online, you don’t know if you are communicating with Jayden from Hornady, or Joe Schmoe from Idaho who is a teenager in his parents’ basement.
It’s relatively easy to create new bullets and new cartridges for yourself. For the cartridges the SAAMI specs will provide all of the data. For bullets, you are going to need to contact the maker or take some very precise measurements yourself.
The big problem is new powders. You need a ton of good data to create a new one and most people are not going to have that data available to them. So it doesn’t have some of the newer powders. (it’s got StaBall 6.5 but not match or HD. Also not many of the Ramshots)
I do find it somewhat fun to play around with when I have spare time also.
For instance, I do believe that reloader 26 indeed is the magic pixie dust powder for 7 prc. Especially if you’re dealing with shorter barrels. If you use GRT and create a load to max pressure with reloader 26, and then with the same bullet create a load to max pressure with any of the VV 550-570 powders, despite the max pressure being exactly the same the reloader 26 will give you another hundred or even 200 ft per second velocity. And, more pronounced with the shorter barrels. There’s obviously more to how a powder behaves then where it sits on the burn rate chart.
I also discovered that when trying to find a lightweight copper bullet in 7 mm and get it going ludicrous speed, my 22-in 7prc is the ballistic twin of my 24-in 280 Ackley at Max loads. But the Ackley does it with about five grains less powder. So is 2 in of barrel worth five grains of powder?
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If you’re not using GRT or quickload you’re basically poking around in the dark with regards to what your pressures look like at different temperatures or charge weights. Brass and primers are inherently flawed as metrics as “pressure signs” can show up at wildly different internal pressures for different brands of cases and primers. That being said these tools are only approximations of reality and require calibration and knowledge to use effectively.
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Discussed on today’s Hornady podcast with Jeff Siewert.
The GRT/Quickload starts around 16 min
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I just got somewhat familiar with GRT the past couple years. By no way shape or form am I fluent in all the features it has. I do find it useful in using powder and bullet combos that are not available in reloading manuals. Basically to give me a starting point. I have not gone back and looked to see how accurate the predictions are after my load is developed and trued the velocity for my load. I do add all my measurements such as grains of water the brass holds and case/bullet measurements. Its fun to see how powders burn rate affects the velocity/pressure curve and try to predict where the best charge weight will be.