The first round tests of my .223 hunting load resulted in one big issue: the primers were backing out.
foo.c‘s guess is it’s the brass, which was brand new Remington.
So I hit Google to see what I can see.
It seems that Remington brass isn’t regarded as the highest quality brass (not like Norma and Lapua), but it’s generally regarded as good brass. So maybe it’s not the brass?
Some things I’m finding in my reading:
- Too short for the chamber. Could be excessive headspace, could be the cases were sized too short for the chamber.
- Hrm. I’m loading to .223 Rem specs, but the Bushmaster is 5.56 chambered. Could it be things were sized just a wee short for that chamber since a 5.56 chamber (compared to a .223 chamber) has a longer leade and headspace dimensions?
- Too low a pressure.
- This might go along with the above. The chamber was slightly larger, thus when the case expanded it didn’t expand
- Chamber wall cling. That is, there’s enough pressure to expand the case sideways to cling to the chamber walls, but because there’s more free space along the axis running through the bullet from primer to tip, coupled with less pressure, now there’s not enough to fill things backwards including pushing the case back against the bolt face so as a result the primer can back out a bit.
- New brass. It just may be formed to “conservative” tolerances and/or have case uniformity issues. Debur the flash hole, uniform the primer pockets, etc.. to help.
- Full length sized brass, similar issues to the above.
This was a useful resource.
Check out this PDF showing the dimensional differences between .223 and 5.56.
It sounds like the primers backing out may be normal for my situation.
If the loads are very weak, unlikely to see primers backing out as there’s probably just not enough pressure.
If the load is perhaps just under max, that’s enough pressure to cause things to back out.
If the load is max to hot, it’s probably more than enough pressure to cause things to sit tight.
What could cause lower pressure? Well, I’m loading a .223 Remington and shooting from a 5.56x45mm NATO chamber, which is going to be just a hair longer. It could also be due to the shape of the bullet (the ogive on the Barnes TSX). It could also be the length at which I loaded the cartridge really putting the bullet off the lands.
This is all just hypothesizing.
The bummer? After talking with foo.c I had resigned myself to just switching to NATO brass (Lake City, WCC, whatever I happened to have). Thus I took all of the Remington brass from yesterday and threw it with some other dirty .223 brass into the brass tumbler to get cleaned up and put in the bucket for reloading at some future date. Thinking about it now, I should have kept that brass: 1. to measure it and see how the size changed after shooting, 2. to go ahead and reload it and try again. Now that it was fired in that chamber, it may have taken on a different and better shape.
So I’m tempted to keep my NATO brass in reserve and continue with the Remington brass. I will pick up a few more dodads at the store, like something to debur the flash holes and to uniform the primer pockets. No harm in that. Then see how it goes. But this time, I’ll reload that same Remington brass and see how it goes. If I still have primers backing out, then I’ll look at other options.
I might even consider doing a test-run of brass this way. That is, instead of using the Barnes TSX bullets, I’ve got some 55 grain Winchester FMJ. I could work up a quick load with some of those to preserve the Barnes bullets.
Ah, so many things to consider. 🙂