LRRPF52 Wrote:I used Quick Load once to predict start loads for .260 Rem using cut-down 120gr GMXs to 95gr, provided by another forum member.
I referenced 95gr V-MAX data, but also took into consideration that the GMX is a monolith, so it would build pressure much faster and resist being driven into the lands, so I backed off of that.
It still blew the primers out. I learned how useful QL was in those situations, which was not much at all. No bullet/powder combo existed for what I was doing, and the predicted numbers were so far off as to be dangerous. I suspect they were over 70,000psi. AR-10 ate it fine, but it was a failed process for sure.
every batch of powder can be different. Gordons realizes that and suggests you calibrate program to your rifle and lot of powder early on in development. Did you change the bullet parameters to your altered bullet. Did you start with a minimum charge using published data from a bullet /powder combo that was similar.
Gordons reloading page propellant correction directions https://www.facebook.com/845221829183230...702341307/
Personally I like to find as many sources when I can to establish a starting load. I will spend hours looking on the net and going through all the published load data I can find before ever dropping the first gn of powder into a case. I always start at a minimum charge and even when I am at the end of charge development I will always choose the lowest velocity node that meets my needs in order to minimize barrel wear and use the least amount of powder. When you shoot 300 - 400 centerfire rounds per month and sometimes more every gn of powder counts.
I would never reccomend using either software tool as the only source for load development if at all possible. Even with the Lapua/Leverevolution development which had no official published data I did a search for user recommended loads on this forum and others then ran the number in GRT and started very low and worked my way up in .2 gn loads
I just sat here and loaded in six bullet/powder minimum/maximum from Hodgdon, Sierra, Berger, Barnes, and Nosler and in all six GRT was conservative compared to the published data. Not saying that is the case 100 % since there are 1000's out there. But like I said there are several free sources online and even with the data books a email or phone call asking for a load suggestion from the bullet or powder distributer is all that I have ever needed to find a start point.