It took me several thousand rounds to learn how to shoot my JP with any consistency. There is a lot of good information in this thread to get you there. Have you tried any 123 gr. bullets? That is what Jp recommends.
https://jprifles.com/document_pdfs/JP Loading Information 2015.09.29.pdf
The three things that helped me the most was learning to trigger folllow through. Hold the trigger back after you fire. I replaced the trigger with a Triggertech Diamond. And I know I'm going to hear about it but I also put a EC tuner break on it and that alone cut my group size down in half. I think a tuner is perfect for the AR10 platform since your limited to magazine length for seating depth. If you keep after it there is a combination that will work for you.
