Thread: Testing a conventional approach to load development

Thanks @gimp for this post. Coincidentally I used the same approach in the weekend for 7mm rem mag load development. I have used it for my 270win before and found it to be very beneficial.

I was a bit frustrated on the weekend during the first stage of the process as the labradar wasn't liking the AA batteries I brought (hence only three readings for the first two strings), and the testing of different charge weights didn't yield the best results with regards to standard deviation and spread, although they were mostly all grouping well at 100m. I have since gone through a process of elimination and found that one of the nuts on my press was ever so slightly loose which may have been hampering a constant neck sizing and tension.

Nonetheless I will test with five shot strings of 70.3, 70.5 and 70.7 charge weights on Sunday and see if I can bring the numbers down a bit while maintaining my average target velocity of 2900fps or more. In the past I have managed to get standard dev of between 5-10fps with 10 shot strings when loading other cartridges so fingers crossed.

In saying that, the velocities and the spread it is producing currently would only make roughly two inches of possible difference in drop between the highest and lowest velocities at 600yards according to my ballistic calculator. The benefits of higher velocities eh? This 2 inch difference is not necessarily excessive for my hunting applications when considering the size of the 'kill box' on the target species. Hopefully refining the load and testing those subsequent strings will tighten the spread and reduce the std dev giving me a piece of mind about making ethical shots at range.