Head expansion indicating pressure.....

[Bart B.]

I have zero interest in arguing with a bunch of innernet exspurts

Yet you seem to claim you are one.

 

[Ggmac]

So , gentlemen, first a question for Bart , if you had your transducer attached to the op rifle what pressure would you think it took to expand the head ? I know it would be a guess , but an educated one .
Next is Al , if you were to witness an expanded head with a known starting load and known to be good components, how much expansion would be too much ? I think I know the answer , at least what I've been taught long ago .

 

[243winxb]

) If the max pressure for 222 Rem is 53,664psi (according to Quickload), at what pressure will the case become "deformed", essentially ruining the case for future accuracy?

Have you annealed this brass?

From Olin.

modulus of elasticity- Cartridge Brass-
Material is 70 copper/30 zinc with trace amounts of lead & iron , called C26000. Material starts to yield at 15,000 PSI when soft (annealed), and 63,000 PSI when hard.
Material yields, but continues to get stronger up to 47,000 PSI when soft, and 76,000 PSI
when work hardened. Modulus of Elasticity is 16,000,000 PSI. This means to pull a 1.000 inch long strip to 1.001 inch long induces a 16,000 PSI stress.
So if you pull a 1.000 inch strip to 1.005 inch long, you get about 76,000 PSI, which is the max obtainable.

 

[Ggmac]

Have you annealed this brass?

From Olin.

If he did ( improperly) I would expect the primers to be loose .

 

[fatelvis]

I did anneal the brass, using my Annealeez, and 750* Tempelac. I made sure if anything, to err on the "under-annealed" side.

 

[Bart B.]

first a question for Bart , if you had your transducer attached to the op rifle what pressure would you think it took to expand the head ?

50,000 to 70,000 psi depending on how hard the brass is for a .0005" to .0010" expansion at the extractor groove root.

Probably 10,000 to 15,000 psi more if a 30 caliber belted magnum case; its thicker.

 

[MagnumManiac]

To the OP, I run my 222 at 55,000psi, tested and proven on a pressure trace.
This number is NOT an average, but the absolute max pressure generated.
I have run the same load/pressure in the same brass for five firings. The brass was annealed on the third SIZING. Not one has expanded more in the head, nor have the primer pockets loosened.
This pressure is the same as set out for 223 ammo, the rifle in question is a Sako L461 Vixen, no hard bolt lift, ejector marks are present and, I wouldn’t expect there to be.

I honestly think your problem stems from something other than excessive pressure. Small primer cases withstand more pressure longer than large primer cases because there is less area for the gas pressure to exert itself against, this is a physical fact that cannot be changed.

Perhaps the tightness is due to your rifle bending the rims on extraction, have seen this before. Then when you resize, they feel tight in the shellholder.

Cheers.

 

[Bart B.]

Small primer cases withstand more pressure longer than large primer cases because there is less area for the gas pressure to exert itself against, this is a physical fact that cannot be changed.

Only if case heads are the same thickness from pocket to rim, so thinks me.

 

[alinwa]

......... Al , if you were to witness an expanded head with a known starting load and known to be good components, how much expansion would be too much ? I think I know the answer , at least what I've been taught long ago .

Kneejerk response. "I have no clear idea what you're asking" BUT, my limit is perceivably looser primer seating with hand seater.

Based on your set of parameters ("known load?") ANY expansion is "too much"

I am not privy to any "Known loads" I guess..... I work up until my max is reached which is;

loose primer seating on the next round.

This is my MAX. In fact it's well OVER my MAX because it's wrecking my brass.

I like to absolutely, without fail safely KNOW where my max pressures lie in any given setup, knowing full well that a very safe load in one setup may well pressure right out on another rifle.

I have 2 Oehler 43 Ballistics Laboratories. I shoot under controlled conditions a lot.

Any new setup, any change in a known setup requires a new load workup. Assumptions can be trouble. Increases of powder charge or bullet weight may not progress in a linear fashion.... I recently worked up 16 loads for a subsonic prototype during which I documented workups using powders from "ultrafast" pistol/shottygun powders like Clays, Red Dot, 700X etc through the gamut and ended up with loads utilizing "ultra-slow magnum" powders like H1000, Retumbo and RL33. Some of the trends were counter-intuitive, some were startling.

My point is, I NEED a solid no-frills but dead accurate approach. Something repeatable.

And I don't give a rat's ass about "actual pressures" ........ it's like "actual velocity". I laff out loud whilst 6 fellers discuss whether their Magnetospeed at 3245fps is "more accurate" than their Shooting Chrony which is giving readings of 3256fps.

Back when I useta' measure stuff I advanced the thought that "natural progression of my casehead expansion was" as follows..... First fairly stiff fireform load pops out the case but not quite to sharp corners and just bumps the casehead up maybe a half thou. Just settles the dust. THEN, I fire for effect with a stout load (which has been WORKED UP TO PREVIOUSLY) and expect another thou, maybe even .0015 after which the case "seasons in" which means it hardens and toughens up to complete stability while only ever growing .002 in diameter, NOT ENOUGH to loosen the primer pockets. At that pressure I expect it to last for 10-20-50, even 100 firings with no change.


But.... K.I.S.S.


I now simply work up a load using the same 5 cases over and over until the primer pockets get loose. I throw these 5 cases away.

Then I back of a bit and start playing with the load in the 3-4gr prior to this over-pressure MAX zone. The load I settle on will be one which DOES NOT continue to expand, even if it takes 5-8 firings to get loose that's too hot for me.

 

[alinwa]

BTW, a clarification regarding the loads earlier referenced, the 300WSM's which failed my long-term testing.

I didn't actually have any classically termed "failures." What I DID find was that a percentage of the loads were hot enough to cause loose primer pockets when heat-soaked at high temperature. No leakers, no popped primers, just "too hot for my taste" which, incidentally is where quite a few factory loads lie. When the WSM came out it was touted as "a short-action magnum which nearly equals the 300WM in velocity." In the ensuing years industry loads were pumped up to where many of the WSM, WSSM and RAUM were, and sometimes still are loaded to high enough pressures that one can fire a factory load in a factory rifle and upon reloading find loosened primer pockets.

Losing the primer pocket on the first firing using virgin brass is too hot IMO.

Rounds like the 243WSSM in the M70 "Coyotes" were notorious for pressuring out, many rifles were sent back to be "fixed" and the three I tested all failed my parameters using factory loadings.

As unpopular as my view is, I remain convinced that the 300WSM (one of my favorite chamberings BTW) is more a "short action 30-06" than a "short action 300WM"

In my case the combination of finding some rounds that were hotter than I like, coupled with the fact that the ball powder DID NOT METER as I'd anticipated led me to the decision to pull the rounds. I metered the rounds instead of weighing them individually reasoning that the variance would be very small using the ball powder.......I expected the rounds to all be "within 2 tenths of a grain." Or +- 1/10th gr....Subsequent testing showed that they WERE NOT that consistent. While I did not actually find any loads in my random testing which were dangerously hot, and while I knew which gun the rounds were expected to be fired through, I could not be certain of the absence of outliers...... rounds which could be maybe 3 tenths off.....


so I disassembled them all.

And went back to individually weighing charges.

I load for accuracy, for consistency, NOT for velocity.