Gas leak root cause

B

brasscollector

New member
Had some gas cutting doing load workup for my 204 and I'm trying to discover the root cause. Had it happen on about 12 out of 25 loads using 2 different powders. I didn't notice what happened until I got home or I would've stopped after the first one. The actual etching to the bolt face is minimal and at this point mostly asthetic.

rifle:
204 Ruger
Ruger M77 mkII 24" sporter barrel
loads tested:
Sierra 39gr BK
IMR 4895 26.0 & 26.5 (3500-3630fps)
Benchmark 24.0, 24.5, 25.0 (3325-3440fps)
Winchester SR primers
Hornady brass (neck sized)

Primers were flat but the edges still had a slight curve to them, no protrusion into the firing pin hole. I pressed out an offending primer or two and they were definitely not loose. Cases have been shot now 4 times (factory loading plus 3 re-loads). At this point I'm leaning towards the brass as it seemingly picked out random cases to affect. I would have just said it was a pressure sign (not sure it isn't) but it wasn't something that happened more or less with increasing charge weights.
 
I would try a magnum or benchrest primer first...I had similar issues when I started loading .204 with standard primers. The CCI 450 or BR-4 and the Rem 7 1/2 have thicker cups than the others. Solved my problems anyway - I tend to use CCI because they are generally more available in the places I shop.
 
I will try different primers before writing off the brass. I'm going to venture on over to cabelas and see if they have any CCI or Remington SM rifle BR. I also prefer CCI over other brands of primers.
 
I assume you are seeing soot/residue around the primers from where the gases leaked passed/through .

How does different primers fix an etching issue ? Are the ones mentioned slightly larger in diameter resulting in a tighter fit ?
 
What I noticed first was the etched bolt face when I pulled it to run some patches through the barrel. I then took a really close look at the spent cases. I could just make out a slight discoloration around the edges of a few primers, not sooty but more like metal that turns color from heat (not sure if that is actually the case but that's how it appears).
I am hoping that a different brand of primer is slightly larger in diameter or harder as others suggested. I have heard stories about bad batches of ammunition from the late 1980s or 1990s (federal comes to mind) that were produced with bad primers which caused much more severe gas cutting so I'm not ruling out a primer. I had also heard that Hornady 204 brass could be suspect after just a few firings but so far no one has echoed that.
The 204 is my only small rifle cartridge so I usually only have a couple hundred primers on hand at any one time. My local supply store sells primers in 100 count lots, but only has winchester on hand. Cabelas carries CCI and remington but only sells by the brick. A friend said he would check his stash and see, he thought he had some Rem 7-1/2s.
 
If the brass has been fired 4x then I'd bet that at some time you loaded them with a hotter than usual powder charge and the primer pockets have expanded. I use a .210" diameter pin gauge to check my large primer pockets and you'd be surprised at how fast primer pockets will expand with certain powder charges. The 204 uses a small primer pocket that is specified to have a diameter of no more than .1745" so you'd need a pin gauge that size to verify that the pockets were no larger than the design specs. When the pockets exceed the max recommended diameter the primers will not expand enough to seal the gasses from escaping.
 
brasscollecter, do you uniform your primer pockets? What kind of primer seater are you using & are you bottoming your primres when seating? Sorry for asking I know your not new to reloading. Just had to ask.
 
I do uniform my primer pockets for depth and remove any whiskers protruding from the flash hole. I seat all my rifle primers using the RCBS bench tool and once uniformed they will seat below flush. If I feel any primers seat too easily I will push the primer back out and chuck the case in the brass bucket. This is where I am rather stumped I guess. I could see the pockets getting loose and causing much grief but the primers pushed back out with a normal amount of resistance. Any of my LR primed cartridges will flatten the primers quite a bit more than what I seen with the 204 and none of them have shown to leak. I should have approx 90 remington #7-1/2 primers to try in the next few days.
 
I've run into at least two different lots of Winchester primers of fairly recent production that had bad cups.

Winchester LP Lot # DHL777G
Winchester SR Lot # DFL569G

The LP primers were purchased in 2014, but the lot number decodes to August 2010.
The SR primers were purchased in 2015, but decode to June 2010 production.

Up to 90% of them cracked or failed to seal. -In at least 8 different lots of brass and a dozen or more different loads.

Like you, I now have a bit of bolt face etching to constantly remind me of Winchester's lack of quality control. (The LP primers were for .458 SOCOM/.475 Tremor -- so also an AR application.)

I'm currently chasing some strange, random piercing issues with another lot of WSR primers in completely sane .223 Rem loads (42-45k psi). So they may be added to the list, as well. (Marked as 2013 purchase.)



In my case, I was able to save all but two pieces of the brass, even though some of the primer pockets were gas-cut. Transitioning to CCI primers that I had on hand was enough to stop the etching/cutting. (CCI #41 and/or #450 [SRM] for the SR, and #350 [LPM] for the LPs --- 90% AR usage, so I might as well run "slam-fire resistant" primers).
 
The flash holes 'appear' normal. They do not seem to be melted out or oversized. I am currently seating to book spec while doing ladder tests and then move the bullet out once I think I have the powder type and charge weight close (at least that's how I have done it in the past). I do not plan on running them into the lands.

I have a fresh box of Nosler brass sitting on my bench. I'm a bit hesitant to potentially introduce a primer problem to my new brass. I was hoping to find out the root of this issue and get a bit closer to where I would like to be (accuracy and velocity-wise) before canning the Hornady brass. Further gas-cutting would be regrettable but at this point I see no reason not to continue.

The lot # on the box of SR primers I am dealing with is HLL630G (2014?). For large rifle I am pretty much a stickler with CCI, I will buy those by the brick.
 
Your covering all the bases, never had that problem as of yet. I use CCI BR2 primers with FC & ADI brass once fired from a friend that doesn't reload. I use a #45 drill bit to clean the flash hole. My last post I was thinking that you may have been hard jamming your loads, it wasn't that. Never had issues with primers, looks like thats what it is.Warrants a call to them. Would like to know what caused the problem.
 
As posted above, there have been numerous problems with Win. primers in the past couple of years concerning primer leakage and blowout. Getting some 7-1/2's may promptly solve the problem.
 
Pinhole crack in the shoulder of the Winchester primer? Hold the ejected primer up to the light. Let me guess, RP brass too?

Win+RP don't mix.

I caught it on my revolver after only 5 pits in the recoil plate. They're kind of in a W pattern to help me remember.
 
Shot through a load work-up this past weekend. Only component changed was to Remington 7-1/2 primers. Fired 20 loads from 24.0gr of benchmark up to 25.2gr (so far) and did not see any leakage. At this point I would be comfortable saying it was a primer issue.
 
brasscollector, you were on the right track all along, thanks for getting back. Problem solving helps all of us. Be Well. Chris
 
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