Aguila Blanca
Staff
After seeing the recent post about Gordon's demise, I downloaded the newest version of GRT and dusted it off -- I had it before, but I don't think I've looked at it for two years or more. I'm a pure novice at manipulating these simulators, so I ran some samples against known data (not mine) to check for correlation. I didn't find any.
First, I had lost my database of Berry's bullets in GRT, so the first thing I did was to re-enter all the 45ACP bullets, and many of the 9mm bullets. The two I generally load are the 230-gr round nose, and the 185-grain round nose - hollow base.
For known data, I looked up an article in Shooting Times that discusses those exact bullets, and conveniently used Winchester 231, which is the powder I use.
https://www.shootingtimes.com/edito...-bullet-weight-gives-edge/99399#ixzz5D6mJdC7P
I entered the data from the article for those two bullets into GRT and checked the results. They were massively different.
I know the bullet dimensions are accurate, because I entered them and I double checked them. I used the same C.O.L. as cited in the article, even though it's a bit shorter than I typically load .45 ACP. I didn't mess with the powder data, I just picked Win 231 and used the data in GRT.
GRT reported the upper level loads as being massively over-pressure. For all of the loads, in both bullet weights, GRT reported velocities ranging from 100 to 200 fps faster than what the author of the article got in real world testing.
For another data point, I looked up results from my early reloading. Using the same Berry's 230-gr RN bullet at 1.2700 C.O.L. over 5.0 grains of W231, I had a minimum of 629 fps, a maximum of 667 fps, and an average of 651 fps. GRT tells me that load should be producing 834 fps. That's a 28 percent error.
I don't expect an exact match, but differences ranging from 6 percent to 32 percent -- with most of them being around 25 percent -- were a bit more than I expected, and make the data fairly useless.
I must be doing something wrong, but ... what?
First, I had lost my database of Berry's bullets in GRT, so the first thing I did was to re-enter all the 45ACP bullets, and many of the 9mm bullets. The two I generally load are the 230-gr round nose, and the 185-grain round nose - hollow base.
For known data, I looked up an article in Shooting Times that discusses those exact bullets, and conveniently used Winchester 231, which is the powder I use.
https://www.shootingtimes.com/edito...-bullet-weight-gives-edge/99399#ixzz5D6mJdC7P
I entered the data from the article for those two bullets into GRT and checked the results. They were massively different.
I know the bullet dimensions are accurate, because I entered them and I double checked them. I used the same C.O.L. as cited in the article, even though it's a bit shorter than I typically load .45 ACP. I didn't mess with the powder data, I just picked Win 231 and used the data in GRT.
GRT reported the upper level loads as being massively over-pressure. For all of the loads, in both bullet weights, GRT reported velocities ranging from 100 to 200 fps faster than what the author of the article got in real world testing.
For another data point, I looked up results from my early reloading. Using the same Berry's 230-gr RN bullet at 1.2700 C.O.L. over 5.0 grains of W231, I had a minimum of 629 fps, a maximum of 667 fps, and an average of 651 fps. GRT tells me that load should be producing 834 fps. That's a 28 percent error.
I don't expect an exact match, but differences ranging from 6 percent to 32 percent -- with most of them being around 25 percent -- were a bit more than I expected, and make the data fairly useless.
I must be doing something wrong, but ... what?