This is an update to post #1,017... in case anyone is wondering, this is a good chunk of the "why/how" a barrel and load using a healthy bullet jump stays so consistent (boring) over its life...
I was having more issues than usual holding a tight group lately, so I started checking my rig looking for a reason as to why (I mean besides me sucking at shooting lol). This meant going over the whole rifle to verify that everything was torqued to spec (action screws, scope mount, etc) and then looking at the possibility that my throat had eroded to the point where my load needed to be tweaked or even maybe me having to work up a new load.
Well, turns out it wasn't the barrel/load (my trigger pull-weight had increased on its own, doubled in weight somehow).
That said, decided to check on my throat erosion: I use/recommend the Deep Creek Method to find one's lands using a dummy round made up of the same ingredients, same brass, same bullet, prepared exactly like the real ones.
I'm jumping 0.100" to the lands (112gr Match Burners, also running "slow" at ~2900fps).
The barrel now has 1500rds on it.
The barrel when new
after 150 rounds on it: lands @ 2.2550".
After 1500 rounds on it: lands @ 2.2545" (actually could be zero, really tough to call if I wasn't closing the calipers too hard once within a thou).
Edit: Remember, loaded in closer to the lands (like the ubiquitous .020" off) usually means cooking off ~0.006" per 100 rounds!!! (
https://precisionrifleblog.com/2020/03/24/how-fast-does-a-barrel-wear/)
Crazy.
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