So I got a weird one today. I was shooting my precision AR15, zeroing my scope, and doing a tall target test to check the scope was mounted on straight and figured it would also be a perfect time to fireform some once fired lc brass i had laying around. I loaded up a very mild load of 21.2gr of accurate 2495/69gr smk/LC22 brass/cci #41 primers/COAL: 2.245/Brass trim length: 1.750". My cartridges fireformed headspace is 1.459" so i set my brass at 1.455". After i finished shooting i was checking my brasses headspace and most were at 1.459" but I also had a few pieces that we actually shorter than 1.455" at 1.453" two thou shorter than what I set it at. How is this possible? Has anyone delt with this before or seen this? My guess is this isn't good obviously but I dont know how to fix this issue since idk why this is happening in the first place. I've never seen this before. So what's everyone advice and take on this situation?
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What's your shoulder diameter before and after?
I've seen it from time to time, depending on the chamber and the die, where (I think) the shoulder is 'out' more than it's blowing 'forward', so the case doesn't appear to 'grow' because it's stretching out radially instead of axially.
I've seen it from time to time, depending on the chamber and the die, where (I think) the shoulder is 'out' more than it's blowing 'forward', so the case doesn't appear to 'grow' because it's stretching out radially instead of axially.
Ok so...
-fully prepped pre-fired brass (1.455" headspace): shoulder diameter=.351".
-fireformed brass (1.459" fully expanded headspace): shoulder diameter= .356".
-fireformed brass (1.453" non-expanded headspace): shoulder diameter=.358".
Just a suggestion.
If you shoot/test someplace where loading at the range is convenient, then working just a few cases for several cycles while starting up a new rig is worth the trouble of hauling the gear out.
This way, you can learn the wants/needs of the chamber and the sizing recipe, learn what to expect for brass life, learn how the barrel responds to cleaning, get an idea of the speeds/bullets the rig likes, have the gun boresighted, all in half a morning.
As always, YMMV
If you shoot/test someplace where loading at the range is convenient, then working just a few cases for several cycles while starting up a new rig is worth the trouble of hauling the gear out.
This way, you can learn the wants/needs of the chamber and the sizing recipe, learn what to expect for brass life, learn how the barrel responds to cleaning, get an idea of the speeds/bullets the rig likes, have the gun boresighted, all in half a morning.
As always, YMMV
I shoot in my back yard basically. So that's not an issue. I've been shooting this rifpe/barrel for well over a year. That's what weird. I've had different brass headspace like some being fully fureformed to the chamber at 1.459" and some at like 1.456" that aren't quite fully expanded but never had headspace end up shorter than before I shot.
Interesting! Today I was measuring headspace on different milsurplus 308 I ran through my Solus a few weeks ago and had the same result with 2010 Privi FMJ and 82 Malaysian ball. I’ve never had that happen either, didn’t even know it could happen. The Malaysian measured the same loaded and fired at 1.625 and the Privi was 1.6245 loaded and 1.623 fired. I only started paying attention to such things last year, so I don’t have much of a track record, but will be watching it in the future.
The other thing I found is that the difference in headspace between my fired brass and reloaded rounds in FGMM brass is .005”. I could dial it back a bit closer to .002”, but I use this same die to load for a M1A and AR10 so I’ll have to get measurements from those rifles before I tweak it. Might be time for the Redding shell holders that allow headspace adjustments so I don’t have to adjust the die for the different rifles.
The other thing I found is that the difference in headspace between my fired brass and reloaded rounds in FGMM brass is .005”. I could dial it back a bit closer to .002”, but I use this same die to load for a M1A and AR10 so I’ll have to get measurements from those rifles before I tweak it. Might be time for the Redding shell holders that allow headspace adjustments so I don’t have to adjust the die for the different rifles.
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