Thread: Testing a conventional approach to load development

Originally Posted by gimp

100m or 100y? @dannyb

yards, of note the targets are not to scale despite the PDF saying they are....

And here is the latest evidence this approach just plain works. A 6mm ARC barrel that I'd shot for 200 rounds or so, showed promise as an ARC with the 103s but never "properly tested". Rechambered to 6mm CM.

Taken to the range last night and a ladder shot up to book max. The results analyzed using GRT (calibrated to the resultant case capacity and actual velocity etc.). It suggested an additional 50-100 fps was still on the table. Not wanting to run this rifle "hot" I rounded the load up to an even number and confidently loaded 50 rounds.

At the range this arvo to test and here are the results, which include the cold bore shot - I got interrupted hence finished at 9 shots. All good for hunting to 500M

Note that the shot order is not as labeled, the cold bore shot is in the middle of the group, maybe #8

I did get humbled a bit later, we went to 571M to shoot some gongs and despite a solid zero from the above group I cocked up the settings between the scope and Strelok and couldn't hit the 6" gong to save myself . .,. It did eventually get sorted but shows how many things can go wrong in this LR game

I just found this thread. Its very interesting and a great practical example of the Hornady #50 and #52 podcasts I watched last week. Thanks @gimp for taking the time to do the test and share it.
I have a new rifle that I plan to load for using this method. Let's just say I settle on a load after 50 rounds. I understand that barrels speed up over the first 100-200 shots. Traditionally this would require retuning the load to get back to the "velocity node". In reality though, the velocity increase should be no real concern accuracy wise and I seem to recall the Hornady guys saying there is no correlation between velocity and accuracy. So it'll just be a matter of keeping an eye on velocity over time to make sure I'm making appropriate allowance in my ballistic calculator for long range work. Have I got the right take on that?
Cheers

I recently got a new rifle. I picked a load at book max of 2209. At 200 rounds it is 50fps faster than 0 rounds. The precision is no different.

Originally Posted by gimp

I recently got a new rifle. I picked a load at book max of 2209. At 200 rounds it is 50fps faster than 0 rounds. The precision is no different.

When I say I "picked a load", I mean -

I set the seating die so that the bullet is some distance off the lands and the COL is around the book max COL - not sure how far off the lands maybe 30 thou
I loaded 30 rounds, 10ea with 2209, 2208, and an old slow batch of 2209
I shot 3 10 round groups
All were fine for precision but the 2208 and the old slow batch of 2209 were a bit slower than my requirements

I then proceeded to select a max load of 2209 as my load at that random OAL, and use it.

Over the first 200 rounds it seems to have sped up around 50fps, precision hasn't changed.

As no-one else has repeated my "test of the test" - we can't say categorically that you should expect the same with every rifle, cartridge, bullet, powder combination - but I haven't seen any evidence to the contrary yet.

Cool, thanks. Coincidentally I will be using 2209 aswell.
Cheers.