Rifle malfunction where I least expected it

[stagpanther]

Yesterday I took out my 270 win build I did a while ago and decided it was time to put some cartridges through it--on the menu were 150 gr interbonds driven by Ramshot magnum. I had problems immediately, stiff cartridge chamberings with difficulty closing the bolt and a few FTF due to the primers not ignited, despite what looked like solid hits from the firing pin.



I thought at the time the problem was either a headspace problem or possibly a problem with the Genix primers, they do have issues pop up every now and then on some rifles I use them with. Long story short, I ended up taking the entire rifle apart, including complete disassembly of the bolt, cleaning and reassembling everything. Things went really sideways when the chambering and firing issues did not go away--that's when the lightbulb went on and I decided to swap bolts with another 30-06 based build--same problems. Even tried a factory-built 270 win--same thing, no go. That's when I finally started taking a closer look at my reloading gear, and upon taking my sizing die apart, found this:



Replaced it with a spare stem and magically the problems disappeared--chambered like greased lightening and no problem touching off the primers. I'm not exactly sure what the crooked stem was actually doing to the sized brass--I assume it imparted an asymmetry somewhere that really had profound consequences.

[sako2]

Case neck most likely have a lot of runout

[stagpanther]

Case neck most likely have a lot of runout

That's sorta what I was thinking--like the case was slightly bent U. Interesting part is how bad the consequences (seem) to have been.

[jetinteriorguy]

Kind of a curious thing, how in the world would it bend the shaft without the decapping pin being damaged first. Usually the pin is sort of the weak link, not the main shaft.

[stagpanther]

Kind of a curious thing, how in the world would it bend the shaft without the decapping pin being damaged first. Usually the pin is sort of the weak link, not the main shaft.

I have no clue; except it came out of an old Lyman die which the stem secures to the die by a screw at the top--so I assume it must have come loose at some point; but it was on very tight when I loaded ammo this go-around. I don't use 270 win very much, so it was a long time ago when I last used it, must have hit something inside the case is all I can think of, though my last step in case prep is swabbing the inside with a pipe cleaner. But I'm willing to accept that I must have bent it somehow without knowing it--in the dim recesses of my fading memory I might have had a stuck case in the die, it's happened to me a couple of times.

[44 AMP]

Kind of a curious thing, how in the world would it bend the shaft without the decapping pin being damaged first.

The answer is simple and obvious to me, but I've been using the "old" Lyman dies since the early 70s.

Just look where the bend is. Not at the top of the stem, not in the upper part where it is held in the threaded plug, but below that.

This kind of bend at this location is 100% operator error.

At some point in the past, a user had the decapping stem screwed down TOO FAR (and clearly didn't realize it), the decapping pin went into the flash hole (and so, didn't bend or break) but the expander plug bottomed hard on the web of the case, just before and the ram reached full extension. Its possible the user didn't even feel it. OR maybe did, and just went "huh, that one was harder than usual" and never checked it out to find out why.

With the expander hard against the web of the case and the ram pushing up its last little bit, there's only two things that can happen. The decapping stem bends /breaks or the threads in the plug portion strip. could be both together, but usually only which ever one happens first and relieves the pressure on the stem.

In your case, the decapping stem bent (bowed out). This only comes from pressure from below.

IF the now bent stem was left a bit loose, so it could "wiggle" a little, (and so line up better) there might not be any noticeable effect on the resized brass.

With the bent stem tightened up, that would put uneven pressure on the case neck and pull the neck out of line some, and the regular seating die would no necessarily "straighten" the neck. I think that was the cause of your chambering issues.

[stagpanther]

At some point in the past, a user had the decapping stem screwed down TOO FAR (and clearly didn't realize it), the decapping pin went into the flash hole (and so, didn't bend or break) but the expander plug bottomed hard on the web of the case, just before and the ram reached full extension. Its possible the user didn't even feel it. OR maybe did, and just went "huh, that one was harder than usual" and never checked it out to find out why.

Sounds plausible; especially the pressure from the bottom part--that makes sense to me, however since I generally position the decap pin for just enough clearance to get the primer out what I think is more likely is that at some point I simply turned the die down too far without realizing it.

[44 AMP]

what I think is more likely is that at some point I simply turned the die down too far without realizing it.

Possible but not very likely, based on the way you say you adjust the pin.
But, more likely, I think if you normally have the sizer die set up for neck sizing.

Ordinarily, the pin will push out the fired primer before the bottom of the expander ball is level with the sizer die body. That is usually plenty of room to keep the expander ball off the case web, even when the die is in firm contact with the shellholder (FL sizing). However, if you set the die body up to only neck size, then it is possible you might have to screw the decapper stem further down than usual, in order to ensure spent primers are pushed out.

IF you did that, THEN, its possible that screwing the die body down further could mean the stem is too low and will contact the case web, likely bending it if the ram is full extended.

Never had that problem myself, since I normally set up to FL size everything. With one exception, .303 British.

[hooligan1]

How the heck you didnt feel that when it happened and every pull of the press handle I would never get..

[stagpanther]

How the heck you didnt feel that when it happened and every pull of the press handle I would never get..

You would think; except it was hard to tell. This is an older style Lyman die which appears to have the stem only held by a nut in the plug at the top of the die--if the plug is not torqued tightly to the die body the stem can move fairly freely side to side.

[Marco Califo]

So, it is not a rifle malfunction but a operator and die issue.
Maybe the title should be updated.
I was expecting something more like the 45 cartridge blowing out a magazine thread.
But, back to this thread, I use a Sheridan Cut-out Cartridge guage, and also Lyman case guage (and plunk & chambering tests) to detect and prevent this type of thing. I found these (and a micrometer) all to be useful data points in not only checking brass before loading, but also for example, for examining military pull-down primed brass, sorting them into loadable and in need of FL sizing groups (needed when bullet puller was off-center).
The cut-out guage is very useful for visualizing & understanding what is going on with the shoulder and neck. Sheridan makes the cut-out dies and had them only for the most common calibers last time I checked (308, 223/5.56, etc). But, today I noticed they have MANY. And higher prices. I am eyeing the 300 Win Mag.
https://sheridanengineering.com/prod...nition-gauges/

[44 AMP]

I've been using my Lyman dies since the early 70s, they've always worked fine for me with the plug just snug (hand tight), never found one that needed to be torqued hard and always found it a real pain in the butt when I bought some used ones and found someone had done that.

The stamped "die wrench" that came with Lyman dies of the era has a cutout for the "jamb nut" and again just snugged down hand tight always worked for me.

I think a small amount of play is intentional, allowing the rod to move slightly so that a slightly off center flash hole is less likely to bend or break the pin.

[stagpanther]

So, it is not a rifle malfunction but a operator and die issue.
Maybe the title should be updated.

Done.

[jetinteriorguy]

Originally Posted by 44 AMP

The answer is simple and obvious to me, but I've been using the "old" Lyman dies since the early 70s.

Just look where the bend is. Not at the top of the stem, not in the upper part where it is held in the threaded plug, but below that.

This kind of bend at this location is 100% operator error.

At some point in the past, a user had the decapping stem screwed down TOO FAR (and clearly didn't realize it), the decapping pin went into the flash hole (and so, didn't bend or break) but the expander plug bottomed hard on the web of the case, just before and the ram reached full extension. Its possible the user didn't even feel it. OR maybe did, and just went "huh, that one was harder than usual" and never checked it out to find out why.

With the expander hard against the web of the case and the ram pushing up its last little bit, there's only two things that can happen. The decapping stem bends /breaks or the threads in the plug portion strip. could be both together, but usually only which ever one happens first and relieves the pressure on the stem.

In your case, the decapping stem bent (bowed out). This only comes from pressure from below.

IF the now bent stem was left a bit loose, so it could "wiggle" a little, (and so line up better) there might not be any noticeable effect on the resized brass.

With the bent stem tightened up, that would put uneven pressure on the case neck and pull the neck out of line some, and the regular seating die would no necessarily "straighten" the neck. I think that was the cause of your chambering issues.

Makes sense. I can see how you might miss this if using a cam over press, they can feel fairly tight with resistance when camming over.

[armoredman]

That's interesting. Never thought of that.