The deeper the rabbit hole, the...
Posted: Tue Jul 30, 2024 1:27 pm
Just a couple of small observations around brass prep that recently surprised me - and may be of interest to one or two others. Firstly, after getting the idea from a youtube video from the 'Primal Rights' guy, I checked, and yes, its true that freshly annealed brass is left with a very thin, slightly gummy exude that you can feel if you rub your finger from neck, down length of case. This of course is also present on the inside of neck, with obvious relevance re seating friction, if not tension. So as suggested, I processed a small quantity of brass with my usual routine of: lube (with 'unique case lube' applied with lube-infused hand-towel), resize, clean in vibrating medium, ANNEAL, grind primer pockets, trim necks, expand neck with mandrel, prime and load. Only this tine I didn't lube necks before seating - something that I personally have until now found necessary for consistent seating tension. For comparison, I then changed the brass prep sequence to: annealing, lubing, resizing, cleaning, and so on. In the later group, presumably due to the removal of the chemical residue (?) generated by annealing, subsequent mandrel expanding was noticeably smoother and more consistent, as was bullet seating. Looks like my neck-lubing days may have passed.
Second little brainwave, and even more trivial: I've revisited my bad habit of not changing vibration cleaning medium often enough. It's a roundabout story: At Saturday's shoot at Cessnock in light drizzle, despite best efforts, my ammo got very slightly wet. More like a 'sweat' contributed by colder-than-air ammo and very humid air. I only shot one 10+2 round because of insane chamber pressure signs - super-hard bolt lift and very strong ejector impressions in case heads (and at home, detection of enlarged primer pockets and too-long spent brass to chamber easily). Then, with this incident front of mind, after prepping a batch of brass using new 'anneal first' routine, I noticed that my prepared rounds were ever so slightly greasy to the touch, perhaps more so than usual with the absence of the post-cleaning effect of annealing no longer in play. I decided to test whether or not the same lubricity issue that wet-surfaced cartridges caused at Cessnock are detectable to a lesser degree with my mildly 'lubed' cases. I shot four x four-shot groups with each of the two test groups, alternating between 'normal' (greasy) rounds, and rounds that I carefully cleaned with a metho-infused rag. No statistically valid conclusions to report, but worth mentioning, as I don't intend to test further. There was no noticeable difference in bolt lift resistance between the two groups, nor any apparent case head scarring. The metho-cleaned group generated slightly slower muzzle velocities, and slightly better groups, but no-way statistically valid. The only sure conclusion of interest I can report is that there was a nearly consistent difference between the two groups in spent case base-to-shoulder measurements: Using my gauge, all 16 cases from the 'greasy' rounds measured 1.559; most of the methods-cleaned rounds measured 1.558, with three measuring 1.559. By comparison, the wet rounds referred to at the start of this paragraph measured 1.565 and wouldn't chamber when back home without very strong closing bolt force. I guess that with lack of traction by brass in chamber walls, spring-back of expanded case is as greatly reduced.
Hope that's mildly interesting to someone - I have switched to the 'anneal first' method, probably dropped neck-lubing, and will keep a closer eye on the condition of my crushed walnut cleaning medium.
Second little brainwave, and even more trivial: I've revisited my bad habit of not changing vibration cleaning medium often enough. It's a roundabout story: At Saturday's shoot at Cessnock in light drizzle, despite best efforts, my ammo got very slightly wet. More like a 'sweat' contributed by colder-than-air ammo and very humid air. I only shot one 10+2 round because of insane chamber pressure signs - super-hard bolt lift and very strong ejector impressions in case heads (and at home, detection of enlarged primer pockets and too-long spent brass to chamber easily). Then, with this incident front of mind, after prepping a batch of brass using new 'anneal first' routine, I noticed that my prepared rounds were ever so slightly greasy to the touch, perhaps more so than usual with the absence of the post-cleaning effect of annealing no longer in play. I decided to test whether or not the same lubricity issue that wet-surfaced cartridges caused at Cessnock are detectable to a lesser degree with my mildly 'lubed' cases. I shot four x four-shot groups with each of the two test groups, alternating between 'normal' (greasy) rounds, and rounds that I carefully cleaned with a metho-infused rag. No statistically valid conclusions to report, but worth mentioning, as I don't intend to test further. There was no noticeable difference in bolt lift resistance between the two groups, nor any apparent case head scarring. The metho-cleaned group generated slightly slower muzzle velocities, and slightly better groups, but no-way statistically valid. The only sure conclusion of interest I can report is that there was a nearly consistent difference between the two groups in spent case base-to-shoulder measurements: Using my gauge, all 16 cases from the 'greasy' rounds measured 1.559; most of the methods-cleaned rounds measured 1.558, with three measuring 1.559. By comparison, the wet rounds referred to at the start of this paragraph measured 1.565 and wouldn't chamber when back home without very strong closing bolt force. I guess that with lack of traction by brass in chamber walls, spring-back of expanded case is as greatly reduced.
Hope that's mildly interesting to someone - I have switched to the 'anneal first' method, probably dropped neck-lubing, and will keep a closer eye on the condition of my crushed walnut cleaning medium.
