Went yesterday to check and reverify the above load.
I had some at differing stating depths as well to check out but all the same charge and bullets. This time when I fired a three shot group of the previous load at the seating depth above to reverify, bolt lift became stiff, and ejector marks on brass. Yes I stopped right there and then. Didn't get in to the short COAL loads for testing.
Caused a bit of concern on my end.
The weather was warmer, but + or - 10 degrees shouldn't have caused this I would think off the top of my head. And it was about about 5 degrees warmer. (that doesn't rule that out but does not bring it to the forefront in my thought.) As 6.5 Staball is a ball powder, and ball is supposed to be temp sensitive, however the Winchester / Hodgdon claim is it isn't, supposed to be temp stable.
Tore down everything loaded, after checking samples. I did not see / observe any massive seating variation, or charge weight. I had not changed the container of powder I was using from, so couldn't have been a lot difference. Each charge was weighed so I don't think it was a case of powder bridging which honestly I was looking for.
So, I dropped the charge by 0.2gr, and seated the bullet 0.002" deeper. Which if it was either of those "should" return the load to a safer configuration and not be at Hodgdon's "book" max but slightly under.
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---ETA the above was wrote two days ago---
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The dropping the charge and seating change worked. When I went yesterday. Groups held close to original. Nothing dramatic . realistic repeatability no hard bolt lift.
Normally I clean the rifle (any) between every firing. This time I didn't, I went three sessions between firing approx. 80ish rounds each session (240 rounds estimated total between cleaning I'm thinking that is the low side) .
So today I decided to clean the bore out of the blue as the range was closed, it's raining etc etc. I noticed a carbon ring forming around the leade when I brushed through on the first pass. So some cleaning was in order. Bore brush and patched jag w/ J-B paste/kroil did work in short order breaking up and removing the carbon.
Giving it some thought as to why, I'm left with every one of those shots was with suppressor, after thinking about the back pressure. That was my thoughts although it could be the powder itself.
Maybe?
I've used the powder and never observed this before.
OK the solution, then is to just stick to the original method of cleaning after every session. Keep the reduced load and seating depth for the 105's .
Now to shift to the Speer 70's which I did do a pressure test on got the upper limit. On that load I was using Staball Match (close to W748 in the burn rate), and good bit faster than the 6.5 Staball.
Thinking about this and using AI via google which returned quite bit stating to abandon my normal staring at 0.010" to 0.020" off jam. So, I'll try the starting in the range of 0.200" into the neck as when I read through the supporting information behind the results from AI it made some sense.
Just a update. Worse thing that happens is it would be a waste of components.
