Measuring case weight/volume after springback could account for some of the variation in the correlation between volume and case weight. Different case springback could vary the volume especially if the annealing is not consistent. If you were to fire two equal weight cases in the chamber that had earlier been shown to have different volumes that volume difference would not matter much on firing because both cases would expand to the chamber wall and I would expect them to deliver very similar velocities.
Hello Alan We pretty much did what you are describing in the episode following this one. You are right and this is where chamber dimensions and chamber clearance really start to matter. Thanks for watching and posting.
@@sdkweber I had seen and commented on this video earlier and think it was very thought provoking, (I overthink things sometimes) LOL. I suspect though that the rifle platform used in this video series is masking some of the conclusive data that can be extracted from these low sample tests. Something like a heavy F Class or benchrest rig capable of 1/4 moa or better mean less noise and be more conclusive. I didn't see a lot of benefit from hunter sporter rifles using advanced reloading teqniques but going to an F Open class rifle the benefits were very obvious. I wonder why you are getting variables in your seating depth. Are you lubricating your case neck? How much bullet tension? I have only experienced that on dry necks where seating was erratic and seating not smooth. I use graphite in isopropyl to inside coat the necks and that resulted in quite an improvement in BTO consistency and cleaner bullet release. Thanks for the video. Cheers Alan
@@54Mizery I have tried lubricating the case necks prior to bullet seating with mica powder but that showed no improvement. What is the graphite lube you are using?
Very cool insight on this topic. I've never weight sorted, as I am still pretty green to reloading of 3 years now. Gonna write down points consider that you raised. Also, being that I'm newer to reloading I'm wondering what the headstamp says on Federal Champion brass. Just "FC" for Federal Champion? I thought FC meant Federal Cartridge. Also very cool polymer casings. I heard those weren't available commercially. Are they reloadable?
Welcome to Extreme Reloading gscotty311. I do not know what FC officially means now. Originally it was the Federal-Champion cartridge company but through all the mergers with Freedom Group FC may indeed mean Federal Cartridge. The polymer cases have a long way to go to make them reliable and affordable. I had a box of these (factory ammo) and wanted to test consistency against brass. They are not reloadable (at least not yet).
I wrote my first comment before the video finished. Very interesting stuff about powders. Can long extruded powders break in compressed loads? It'd be interesting to see how many did break and if that does change the burn rate and how much pressure it affects. We're talking a lot of motivation and high end equipment to track that data accurately. And like everything else in reloading, it's one of hundreds of variables. But it's still fun lol!
Yes it is fun isn't it. I think you are right that compressed loads likely break some of the kernels of extruded powders. That may be the reason why we see more erratic velocities sometimes under compressed loads. I try to avoid compressing powders for a number of reasons. While there are hundreds of variables to consider, I am trying to identify the primary driver variables first. We see somethings have little to no discernible effect, other variables have a range of acceptable values (tolerances) and others are important to get exact. Thanks for watching and posting.
Just trying to process this a little more. So if the thicker walls of the body of the case are not necessarily responsible for less volume inside then it seems to me that the only way to account for the change is that the circumference and thickness of the case head is accounting for more of the OAL. There is more brass in the base of the cartridge filling up the cylinder from the bottom as it were. Is that possible? Also, if you have a sonic cleaner, I wonder if there's a way to make a jig or frame that would allow you to place the filled cartridges in the empty cleaner and allow the vibration to settle the powder down inside the case. Wait a few seconds, add more to the case and repeat until the cases won't accept anymore. Then measure on the scale.
Hello Aaron and thanks for watching. Great ideas here again. I think the lack of correlation between case weight and volume is entirely because I cannot get a reliable, repeatable measurement on case volume. Your ideas is a good one though to settle the powder, add more, etc.... I might want to try that. I bet I could get small loading block to fit into the ultrasonic cleaner and if it makes enough contact should settle the powder in the case. The thickness of the case neck may not be the same as the thickness of the case body. It is also possible that the case head is "larger" also. Lots of guessing here on my part though. Case weight is an easy one to measure and sort by. Our next video will look at the effect on precision of intentionally varying the consistency of case weights. Thanks for watching and posting.
