More on the why of Click

B

Boyd Allen

Active member
There have been numerous threads about the problem of a click at the top of bolt lift, when extracting a fired case.

I thought that a few numbers might further illuminate the matter.

using an old case a short piece of rod (slightly longer than the case) and my dial calipers, I have determined that the thickness of a .220 Russian case web (the part of the case between the bottom of the cavity that contains the powder to the bottom (head) of the case) is around .150". this is about .015 above the top of the extractor groove.

The standard dimension for shell holders, from the top (face that would contact the bottom of the die) and the surface that the head of a case rests on is .125"

Dies have radii at the bottom (nearest shell holder, as installed in a press) of their inside diameters.

These radii increase the length of the portion of the case that cannot be sized by the die.

Depending on the depth of bolt nose, end of nose to back of barrel clearance, and back of chamber chamfer/radius, a narrow band of the part of the case that cannot be directly acted upon by a FL die may fall within the portion of the chamber that directly supports the case as it is fired.

If hot loads are fired, the web of a case will grow in diameter, increasing the diameter of the case just in front of it. Typicaly, this portion of the case is supported by the chamber.

If a sufficiently small based sizing die is used, the band of the case that cannot be directly reached by the die will be reduced in diameter as the sized area immediately in front of it is reduced. (pulled down slightly along with it)This will allow the case to be chambered without interference.

The next time that the case is fired, the unreachable band will realign itself (pop back out to its pre-sized dimension)with the OD of the web of the case, resulting in a narrow band of interference fit that requires the bolt to be lifted with greater force to break the grip of this interference, and begin the extraction of the case from the chamber. It is this more forceful striking of the primary extraction cam by the root of the bolt that creates the click.

If the chamber is enough larger than the web diameter of the case, the web will not grow to an interference fit before the primer pockets become too loose to be usable.

Conclusion:

The dimension of the back of the chamber should be relative to the diameter of the web, with sufficient clearance so that it is not possible for a click to develop later in the useful life of the case, and the base ID of the sizing die should be dimensioned from well fired brass, to create the minimum reduction in diameter of a case that has been work hardened to the maximum likely to be encountered.

comments? Did I get it right?
 
Boyd Allen said:
There have been numerous threads about the problem of a click at the top of bolt lift, when extracting a fired case.

I thought that a few numbers might further illuminate the matter.

using an old case a short piece of rod (slightly longer than the case) and my dial calipers, I have determined that the thickness of a .220 Russian case web (the part of the case between the bottom of the cavity that contains the powder to the bottom (head) of the case) is around .150". this is about .015 above the top of the extractor groove.

The standard dimension for shell holders, from the top (face that would contact the bottom of the die) and the surface that the head of a case rests on is .125"

Dies have radii at the bottom (nearest shell holder, as installed in a press) of their inside diameters.

These radii increase the length of the portion of the case that cannot be sized by the die.

Depending on the depth of bolt nose, end of nose to back of barrel clearance, and back of chamber chamfer/radius, a narrow band of the part of the case that cannot be directly acted upon by a FL die may fall within the portion of the chamber that directly supports the case as it is fired.

If hot loads are fired, the web of a case will grow in diameter, increasing the diameter of the case just in front of it. Typicaly, this portion of the case is supported by the chamber.

If a sufficiently small based sizing die is used, the band of the case that cannot be directly reached by the die will be reduced in diameter as the sized area immediately in front of it is reduced. (pulled down slightly along with it)This will allow the case to be chambered without interference.

The next time that the case is fired, the unreachable band will realign itself (pop back out to its pre-sized dimension)with the OD of the web of the case, resulting in a narrow band of interference fit that requires the bolt to be lifted with greater force to break the grip of this interference, and begin the extraction of the case from the chamber. It is this more forceful striking of the primary extraction cam by the root of the bolt that creates the click.

If the chamber is enough larger than the web diameter of the case, the web will not grow to an interference fit before the primer pockets become too loose to be usable.

Conclusion:

The dimension of the back of the chamber should be relative to the diameter of the web, with sufficient clearance so that it is not possible for a click to develop later in the useful life of the case, and the base ID of the sizing die should be dimensioned from well fired brass, to create the minimum reduction in diameter of a case that has been work hardened to the maximum likely to be encountered.

comments? Did I get it right?
Click to expand...

If I understand you correctly.............I do not think this a correct evaluation, at least in all the different die/shellholder and barrelled/actions that I have used.

An indication that this is most likely not the problem of the "infamous extraction click", is that cartridge insertion and bolt closure would also have interference problems due to the die not sizing the unsupported web area, which is not what I am hearing from others that are having the "click" problem....................Don
 
Don,
Thanks for the post.

The area that I am referring to is just in front of the web. I guess it might be more correct to say that the bottom of the die may size it indirectly, that it is pulled down slightly by the area that immediately adjoins it, that the die can size, this because the brass is so thick in this area that an abrupt transition is not likely.

Once, I seated a bullet in the neck of a fired case, that had a definite click, chucked the neck (prevented form collapsing by the bullet) in my cordless drill, positioned the case so that it was supported at the back, and held a coarse diamond lap, parallel to the CL of the case, against the bottom of the case, so that it hung over the extractor groove and reduced the area immediately in front of it by a couple of thousandths. After that, I polished the area with 0000 , sized the case and fired a hot load, that previous to the spot reduction, would have produced a click. There was no click. I had reduced the diameter of the web and the portion of the case immediately in front of it, to something approximating their original dimensions. It is my contention that the growth in diameter of the web, under repeated hot load firing pulls the case wall next to it out with it, and the die lacks the reach to deal with this area effectively, because in order to do so it would have to reduce the diameter of the web.

Perhaps your articulate disagreement, will spark others to join the discussion, and we may learn from what they bring to the table.
 
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Boyd

is right. I have had terrible clicking on my 22 Beggs and determined the reamer base is a little too small for the brass. I polished out the first .100 of the chamber about .002 to relieve the web area and the clicking has gone completely away. I now order most of my reamers .002 oversize on the end.

With the normal size chamber, you can size down the base and make the boltfall go easy, but the click will still come back after the firing. I believe the only way to fix it is for the chamber to be bigger or the brass base to be cut.
 
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My first attempt with a wildcat, nearly 30 years ago, was bolt click
from day one. It was a 30-30 case made to 22ppc capacity and everything forward of the body shoulder junction was ppc. What we call
the .200 basic dimension at the base of the case was fine for the brass I used to develope my dimensions. I however came across some DWM
cases from canada that were somewhat nicer. The base dimension was to close to the chamber dimension and bolt click was there at the beginning.
I don't believe its the solid portion that expands and causes this, but the thicker brass just above this. It is very well supported by the solid portion
and quite resilient. Polishing the chamber solved this, but is not the best
solution. Its very difficult to keep it from becoming out of round. I eventually
had a larger reamer made and never had another problem.
Although dies don't often come down as far on cases as we might hope for,
it can be found with a micrometer that some sizing still occurs there. The old
sako cases which had a balloon head were very bad,Nearly impossible to find a die that would size down that far. Polishing out the ID of the chamber at
the mouth of the chamber got you a few more firings, and then it came back
in spades.
 
Why wouldn't the brass continue growth into any dimensions chosen?

I've used .0005" over at the .200 datum for awhile now, and watch it during load development. Once I reach clicking(~.0005 growth) I back down, tossing that case in the trash. This, because it's ruined once it's yielded there. Prelude to loose pockets, or seperation..

Seems like your opening the chamber to save brass yielding from excess pressure(usually greater than 60Kpsi). If that's what you need and it works, then this is a good find, provided the problem isn't simply a lack of sufficient barrel steel around the chamber -for your pressures.

But why wouldn't the brass just fireform right back into the same issue?
Is it because the brass expanded is then more affected by dies?
Is it because of springback in that region?

Just hard to picture cases surviving such a fix in the longterm..
 
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mikecr said:
Why wouldn't the brass continue growth into any dimensions chosen?

I've used .0005" over at the .200 datum for awhile now, and watch it during load development. Once I reach clicking(~.0005 growth) I back down, tossing that case in the trash. This, because it's ruined once it's yielded there. Prelude to loose pockets, or seperation..

Seems like your opening the chamber to save brass yielding from excess pressure(usually greater than 60Kpsi). If that's what you need and it works, then this is a good find, provided the problem isn't simply a lack of sufficient barrel steel around the chamber -for your pressures.

But why wouldn't the brass just fireform right back into the same issue?
Is it because the brass expanded is then more affected by dies?
Is it because of springback in that region?

Just hard to picture cases surviving such a fix in the longterm..
Click to expand...

Mike,

I shoot cases at high pressures, the 70-80,000psi range, "upper node in the PPC" range........ and shoot them 20-40-60-100times with no case growth, no "brass flow" and no clicking. Brass doesn't "flow" nor "grow" on its own.

I do this with a wide variety of cases. All of them run hot, right at the edge of primer pocket failure.

Fitted dies and an oversized chamber isn't a "fix", it's the solution to an existing problem.

al
 
So then

There is a place where if one has big enough chamber, the web area of the case won't ever grow enough to cause the click? Why does the web grow in the first place to cause the click in the smaller chamber size?

Pete on Vacaton in Nova Scotia with a "Friend" :D
 
Under the pressure of repeated hot load firings the web of the case acts like a raw hamburger patty being pressed between the palms of your hands.

The expansion of the diameter of the solid portion of the head is not contained by the chamber. It does eventually create an interference fit right in front of the web, as the case wall, in that area grows larger, because the thing that is is attached to is growing. The head is the support that drags the area just above it to a larger diameter as it expands. Ideally, a FL die would size right up to the solid part of the head. In the real world there is some tolerance stack that has to be allowed for, and which prevents this from happening.

In any case, I guess that my point is that there is a sometimes unfortunate tendency in our sport to assume that things that fit more closely are automatically better. I think that there is ample evidence that in the case of specifying the dimension at the mouth of a chamber, this is not the case. You can make it close everywhere else, but give it a little more room at the back. There are numerous credible reports that this prevents the click problem, and is no disadvantage. It is not that I am suggesting a fix, so much as trying to spread information as to what constitutes proper reamer design, a sort of mass inoculation, as it were. (Actually I am secretly in the employ of a consortium of reamer manufacturers, who are looking for ways to increase their collective sales;-)
 
This is how I see it;
1st the NORMAL,
Brass might as well be made of tin foil, as it expands into every nook & cranny of the chamber under pressure. A difference is brass is thick, alive, and springs back.
But when the brass expands beyond a certain point(I call it yielding), it's usual springback is compromised some.
So once reaching the point where bumping is needed, it will be needed from then on. Same with lower body sizing.
Anyone can 'neck size only' until that don't get it. And from then on, body sizing will be needed..
The thickest part of the case will take a pounding and spring right back -until it don't. Until it's given up the ghost..
Then the chamber comes into play.

The chamber also expands, and it's springback is damn reliable short of catastrophe.
Once brass springback is reduced to less than that of the chamber, you're left with interference fits.
Stiff turn & wiped headstamps because the shoulders quit springing back.. A 'popping' extraction to free the lower body from it's chamber's death grip..
The latter happens even with normal loads when people don't provide enough barrel steel around magnum chambers.

This brass, ruined in my view, can be sized back to chamber just fine. Doesn't 'fix' anything though as the brass will just balloon back out, springback a little less, and again be squished into difficult extraction by the rebounding chamber.

This is what I see as ABNORMAL;
You guys running nitro kill your brass.
And with oversized chambers, you'd take the fight right out of it from the first firing.
Based on Al's input, it seems a good thing where you run.
You can more easily control dimensions on dead brass because it doesn't fight back. Less radical sizing, and dimensions that actually hold for more than a day before chambering.. Brass taken to the described 'fix' would no more fight back the chamber, than dies.
In a sense, you're turning brass into thick tin foil.
If you could anneal case bodies precisely/safely down to but stopping short of unsupported case, you would meet the same results.
No more click. The witch is dead.

That's just the way I see it.
I think it's a good move for extreme loads with limited cartridges, but would never work for anything else.
 
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You know this from solid experience?

BTW the click ,that is the topic of this discussion, happens even when brass is FL sized every time that it is fired, and does not, under otherwise identical circumstances, with a properly dimensioned chamber. Many of us never neck size, preferring properly fitting FL dies. I would guess that the reason that this discussion does not apply to many situations is that most chambers have enough room at the back to prevent it from occurring, also because we typically reload a small set of cases over and over, with the result that we run into situations that a varmint shooter will never see reloading a much larger group of cases fewer times each. Another reason that Benchrest is different is that we are mostly running a non-SAAMI caliber that developed its traditions of chamber dimensions before loads tended to be as hot as is common these days. If you have too close a fit between the back of the chamber and the unfired brass in any caliber, you can have the same problem, if warm loads are used. There is nothing special about any particular caliber in this regard.
 
My 2 cents worth

I really don't know what the chamber dimensions and die specs should be, but this is my take on the subject.
If the bolt closes on a round without undue effort, it IS smaller than the chamber. If the load is normal for benchrest, it IS hot, and the case will expand to fill that chamber. There IS some springback of the case material.....but as all of you can attest, you cannot bend a coat hanger 180 degrees one time and break it. It takes several attempts. You also can attest that the coat hanger WILL eventually break.
That case is no different. Those of you who say they have 100 loadings on a set of cases are defying the odds.
I shoot 1 rifle and usually go to a match with 20 new pieces of brass. By the end of the day on Sunday, the neck tension is going away, the click is coming into play, and the primer pockets are getting tight enough (yes, tight) to make reloading a pain.
The brass gets pitched, and I start anew for the next match.
BA
 
There is an excellent article in the April 2009 issue of PS about Brass Management, by John Lewis. In the article he describes how he makes a ring die to squeeze the base of the case back to correct dimensions. Its probably not a new idea but a darn good one. I think I just may have one made. Take a look, see what you think.

Donald
 
I have to agree about chambers being to small at the rear. As to case trimming, never had a problem with any case with a 35 degree or more shoulder. One trim after fire forming and the case never needs it for it's long life. I do a lot of annealing on most of my fire formed brass and I back down on powder when primers show any sign of leakage. Primer pockets are the one thing I pay close attention to, they open up and it's time to put them in the trash can. :D
 
If you order a reamer that is the correct size relative to your brass, a properly fitting sizing die is all you will need. For a one time deal, setting the barrel up through the headstock, and polishing out the back of the chamber by a couple of thousandths is, in my opinion, a better approach. You might want to reread Jerry Stiller' post. He no longer has the problem. I am amazed how many shooters avoid taking a close look a their reamer dimensions, preferring instead to put a band aid on the problem, instead of getting to the root of the problem. It makes me wonder how many have actually come up with their own numbers, for well thought out reasons, when filling out an order form for a custom reamer. While I probably wouldn't go quite as far over head diameter as Alinwa, he has it right in all other respects.
 
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Pete Wass said:
There is a place where if one has big enough chamber, the web area of the case won't ever grow enough to cause the click? Why does the web grow in the first place to cause the click in the smaller chamber size?

Pete on Vacaton in Nova Scotia with a "Friend" :D
Click to expand...

Pete,

If you're really interested....... the size of the chamber has absolutely NO BEARING on casehead growth.

In My Opinion.

My opinion is based on using 5 differently sized reamers for the .243AI, 5 different 6BR reamers and 3 different .308 style reamers all in successive base sizes from .002 over virgin brass up to .009 over virgin brass. I've used 3 different 6PPC reamers and am getting ready to order my own to be spec'd at SEVEN THOUSANDTH'S larger than the brass case. I've been scared to do this in the past because the three PPC reamers I've used are "proven winners."

My future PPC barrels will be completely off the charts, it'll be up to me to "prove them winners" :D

I will not live with the click.

I refuse to anneal.

And I require my neck tension to remain consistent day-to-day, week-to-week and month-to-month.

I furthermore require that my brass require no maintenance, that the brass NOT GROW. If brass is "growing" it's just a matter of time before you get head separation. The way I work I just can't risk this. I'll often grab up 10 cases and spend 6-8hrs straight with these ten cases just loading-shooting without a thought for checking the cases. I can't afford for a case neck to lengthen and crimp nor for a case to pop. My chamber necks are too short for factory cases.

I recently was playing with my 30X47L............ whipped up a dozen cases, fireformed them and just went to town. 15 firings later I mic'd 'em all out. No change. This was 118's at 3250+fps. You know the math. :)

The reason that the casehead grows in diameter is because the working pressure of the case has been exceeded. It is currently MY OPINION that this is the result of gas being metered into the primer pocket and hydraulically expanding the casehead.

It is further MY OPINION that you cannot "contain" this growth. I've tried with closely fitted chambers and fitted boltfaces...... both were a complete failure. In pure fact my oversized chambers make the same pressures/velocities as my tight ones. And cases fail at the same point.

The difference is that the fat chambers DON'T CLICK! Now, that said, when I load too hot and expand the casehead (SAME pressure point with min or max chamber) then I've found my MAX for that condition.


If others are "containing" caseheads via chamber dimensions then so be it...... I'll no doubt try it again. But fifteen years of experimenting with chamber-base dimensions haven't shown it FOR ME.

Gimme WIDE

Gimme FAT!

and absolutely persnickety die fit and setting, down to the half-thou.


Ohhhh, and also completely contrary to what others have found :p

I've found that the springback capacity of my cases INCREASES with age! As the brass gets harder (springier) it'll spring back a solid repeatable thou+ whereas soft brass will often spring back only a half thou. I was recently shooting my 6X47L on a cool day, pushing 108's at 3150 which is smoulderin' right along pressurewise, 100fps under my MAX, and the cases were just FALLING in and out. I got a little worried that my die had moved. So I added two thou to my die shimstack. next firing I was cranking the bolt closed with my thumb.............. 'bout to gall my lugs.

I took out the .002, went back to shooting. Checked for "growth" an hour or two later.

nuttin'


opinionsby



al
 
Al,
I know that one of the reasons for going so big in the back is so you can see uneven expansion in fired cases, and use that to sort them, but that aside, what was the minimum over case diameter that solved the click problem?
Boyd
 
Boyd,

I'm gonna' go out on the proverbial branch here... :) ... I realize that the minute I put a number on this it changes the entire picture, makes it quantifiable and arguable...... Conversely, it allows others to grab a number and reach for their wallet and try this experiment with me! ;) (MOST people will continue to sputter and whine, live with the click or chuck perfectly good brass just as it starts to shoot)

I'm going to SWAG that for a PPC the magical number is .004-.005

BR or 47L case it's more like .005-.006

.308 sized cases are similar, around .005-.006 but there are so many case options that I'm still kinda' floundering around here.

I've used;
Win 300 Sav, .243 and .308 brass.
URBR.
Norma .243 and .308
Lapua .243, .308 and 6.5X47L

And of course I've tries the others like Fed/Rem/RWS/Hornady etc.......

I'm just starting to work with the huge Winchester SM cases.

I'm currently working in the .007-,009 range because I'm not really concerned with the "minimum required."


And I'm still playing with this, still experimenting. I find that .004 is too small to allow for ANY casehead expansion and that for me I need to allow for as much as .002 expansion just in seasoning the case. For others it's possible that .004 is perfectly adequate. I'm creeping further out on the limb when I state that with my lot of 6.5X47L I can observe casehead expansion of .003 and more and still not risk leaking around my pockets. With H4350 and big honkin' bullets......

I've got some cases that have expanded .005, so large that they'll no longer go into the shellholder in my Hood, and I've set these aside as the primers are so loose that they may leak. I will end up loading these as coyote rounds to be used and thrown away in the field. In a 700-based hunting rifle. To make them work I'll probably seal the primers in with Bob-N-Roys or fingernail polish. IMO they're not loose enough to accept a cigarette paper altho I'll prolly try it.......since't I DO have them in my shirt pocket ;)


In the manuals I've read they speak of casehead expansion as a subtle phenomenom. They talk of blade mic's and expansions of .0002 and "a half thou" and "look for movement" such. I have not found this to be the case A'tall. Casehead expansion borders on gross brass movement. I actually gauge a lot of it. I've got probably 10 .473 shellholders and of course they vary in size. I use two of the tight ones for gauging, just saves a step. Gauging also allows one to check concentricity, for observational purposes.

In a perfect world my current cases mash out about a thou as I shoot them in and then they just STAY there. Primers begin to seat smoothly without the hideous krunch/clik, I can feel them seat and crush. By the third or fourth loading the brass will have become a tractable, consistent part of the equation. I can fuh'GEddabou'dit and shoot.......

to others,

Understand that when I say "my current cases" I'm referring to a lot of first-run 6.5X47L cases that I'm using for 6 different barrels in three chamberings. I've got blocks of 6BR and 6PPC cases that are YEARS old because I'm not shooting short-range stuff much. I'll grab these out and shoot an agg or two at any given time, mainly to test range conditions. Some of these sets have been fired 30?-50?? times. I long ago quit keeping track.

Furthermore, to all reading this who don't know me, understand that I'M NOT SHOOTING THESE PPC'S and BR'S COMPETITIVELY like many others here. I established my baselines years ago and I'm using these guns as "known quantities" against which to baseline. There are many competitors here who will scoff at me using brass for a long time. (There are also many competitors who likewise DO use their brass for a long time but they're not the vocal sort ;) )

and this is all immaterial anyway.

This is an internet forum.

I ain't sellin' nuttin'.........

Go out and TRY THIS STUFF!

report back....

:)

al
 
Boyd Allen said:
If you order a reamer that is the correct size relative to your brass, a properly fitting sizing die is all you will need. For a one time deal, setting the barrel up through the headstock, and polishing out the back of the chamber by a couple of thousandths is, in my opinion, a better approach. You might want to reread Jerry Stiller' post. He no longer has the problem. I am amazed how many shooters avoid taking a close look a their reamer dimensions, preferring instead to put a band aid on the problem, instead of getting to the root of the problem. It makes me wonder how many have actually come up with their own numbers, for well thought out reasons, when filling out an order form for a custom reamer. While I probably wouldn't go quite as far over head diameter as Alinwa, he has it right in all other respects.
Click to expand...

I cannot prove this but I think Jerry's solution may delay the click issue depending on brass age and/or action type but it may creep back in,the properly made die that sizes the base and gives about 1/2-1 thousanth bump is a permenant solution.
 
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