Where's Case Head When Round Fires? - Page 5

F. Guffey · May 22, 2019, 10:00 AM

Quote:

I think what I posted was clear enough. If not, you first need to detail strip your rifle then learn how each part's fit and function changes case fit to chamber using a primed dummy round. Then get or make a case headspace measuring device then learn how to use it. Otherwise, understanding exactly what I did would not be understood.

Make a case headspace measuring devise? I seem to be the only reloader that can make case length measuring devises; in my opinion it is not a difficult task because my cases do not have head space. And then there are those that have an infatuation with go-gages, no go-gages and field reject length gages. I have never found a good fitting gage for the length of the chamber from the shoulder of the chamber to the bolt face.

I have modified go-gages to measure the length of the chamber from go-gage length to infinity in thousandths. I have used field reject length gages to measure go-gage length chambers. And then there are short chambers.

I purchased a barrel that was being advertised as 'short chambered'. I had to ask; "How short?” They claimed the chamber was finished reamed to within .020". The barrel arrived, I measured the length of the chamber from the shoulder to 'case head protrusion', the case head protruded from the barrel .360". I did not have a roughing reamer, meaning; at that rate the reamer was going to have a short life. Most would expect the reamer to finish 20+ barrels.

I understand most are very confused but; where do you find gages for short chambers?

F. Guffey

Bart B. · May 22, 2019, 10:23 AM

Quote:

Originally Posted by F. Guffey

Make a case headspace measuring devise?

Yes, with the caliper I bought to measure case length and a half inch long bushing with a .375" inside diameter. Then calibrate it with a GO chamber headspace gauge to read the gauge dimension.

Bart B. · May 22, 2019, 12:13 PM

Quote:

Originally Posted by stinkeypete

I don’t even understand what you are talking about and I have a degree in physics.

How far will an unrestricted 500 grain cartridge, whose head is resting against the bolt face and its headspace length is .003" less than that of the chamber, be driven forward by a 2.5 ounce firing pin pushed about 8 fps by a 26 pound spring force?

stinkeypete · May 22, 2019, 12:57 PM

It will be driven forward until the the force of the rim engaging the extractor(s), friction along the case walls, or the chamber against the case shoulder exert an equal opposite force...

assuming the 500 grain case moves before my mighty dollop op 10 grains of Unique goes “boom” at something like 1200 FPS in between the firing pin and the shoulder of the cartridge and the brass doesn’t swell in the chamber.

Is a firing pin really 2.5 ounces in a rifle?
I guess I need to take my bolt apart. As it’s a Rem model 30, I bet it’s been 100 years.

I see why twin extractors might be a feature now.

F. Guffey · May 22, 2019, 01:02 PM

Quote:

How far will an unrestricted 500 grain cartridge, whose head is resting against the bolt face and its headspace length is .003" less than that of the chamber, be driven forward by a 2.5 ounce firing pin pushed about 8 fps by a 26 pound spring force?

When you started that cute little saying about the firing pin driving the case, powder and bullet forward to the shoulder of the chamber I suggested you put more thought into the 'cute little saying'.

And now? you have got the bullet, powder and bullet weighing 500 grains. I do not believe you will ever get to the point you understand my response when I said my firing crushed the primer before the, case, powder and bullet had a chance to move. And then I suggested if the reloader had a clue as to what happen to the case after the trigger was pulled they would know if the case moved.

And here is another question on another forum with memebers trying to prove 'it can not be done; and if 'it' can be done it will be your ideal.

F. Guffey

F. Guffey · May 22, 2019, 01:21 PM

Quote:

It will be driven forward until the the force of the rim engaging the extractor(s),

And if that was true it would be necessary to replace both the front and rear bumpers in a rear-end collision. I have no ideal why it would be different with the firing pin. When the firing pin strikes my primers a dent appears before the case, bullet and powder know their little buddy has been crushed.

And then one day I chambered an 8mm57 round into one of my 8mm06 chambers.

Had the case, powder and bullet taken off for the front of the chamber my case would have been ejected with a neck, shoulder and case body with a good chance the case head would have suffered case head separation.

But no, the case was ejected with a long case body from the shoulder to the case head and a shoulder where the neck should have been. I could ask; "WHAT CAUSED THAT? What does that mean? It means the firing pin did not drive the case forward. BUT according to Bart B. the case was driven forward until the shoulder of the case collided with the shoulder of the chamber. BUT if that happened the case would have been ejected with a neck and shoulder.

The shoulder of the 8mm57 when chambered in the 8mm06 has .127" clearance and now? WHERE Is THE CLEARENCE?

If the clearance was between the bolt face and case head the firing pin would be .060" too short to make contact with the primer.

F. Guffey

Bart B. · May 22, 2019, 03:52 PM

Quote:

Originally Posted by stinkeypete

It will be driven forward until the the force of the rim engaging the extractor(s), friction along the case walls, or the chamber against the case shoulder exert an equal opposite force...

What is your rifle's extractor minimum clearance to the bolt face?

How thick are the case rims?

What is the difference between the loaded round's and barrel chamber's headspace? It is called head clearance, the space between case head and bolt face with the round forward against its chamber headspace limit.

F. Guffey · May 22, 2019, 04:26 PM

Quote:

It will be driven forward until the the force of the rim engaging the extractor(s), friction along the case walls, or the chamber against the case shoulder exert an equal opposite force...

That sounds like physics but the force on the case wall and chamber wall does not kick in till the bang expands the case and then comes one of those 'and then' moments. And then the case locks onto the chamber; it sounds simple but when the case locks onto the chamber and the case head is not against the bolt face the case head has no choice but to stretch between the case head and case body.

And that is the reason I am the fan of cutting down on all of that case travel. You being a physics person there is more to 'it' than the killer firing pin strike; I say that because there is another factor (or two) the experts will not acknowledge or recognize. Feel free to contact me off line.

F. Guffey

Reloadron · May 22, 2019, 04:30 PM

OK, I have a question. Way back in post #55 I posted the chamber specifications, well the headspace dimension of one of my .308 Winchester bolt guns. The chamber headspace dimension is 1.632". The bolt will close, albeit with some minor effort on a 1.632" headspace gauge but will not close on a 1.633" headspace gauge. That tells me that my chamber, bolt face to shoulder datum is 1.632" and that is as good as it gets.

The firing pin protrusion on this rifle is 0.060" and I admit I haven't a clue what the spring tension is or the travel distance of the firing pin is or for that matter how much the firing pin weighs so I can do any velocity times mass nonsense to derive the force with which the firing pin actually strikes the primer with. I can tell say with authority that when that sucker hits the primer there is a bang. How close to my bolt face is my case head? Well not sure about that but I can with authority tell you it sure as heck can not exceed 0.002".

Finally, I can also say with certainty, that if I remove a once fired case from this rifle which went in the rifle with a 1.630" measurement from case head to shoulder datum it will measure, case after case at 1.631" (approximately). Approximately means maybe +/_ 0.0005". I can say with certainty that if I deprime those cases and put in a new primer, seated 0.003" to 0.005" below the case head I can chamber and pop those primers all day long and that case will never grow. Matter of fact if I resize those cases to 1.630" and do the same thing, including trim to a nominal 2.005" nothing is going to change.A primer pops in a wide open case and what little gas there is exits the open muzzle.

Finally, with my case held to the bolt face by the extractor, regardless of extractor clearance, and distance between case shoulder and chamber shoulder can never exceed 0.002". That is as good as it gets. There is no way the case can grow in a bolt gun to exceed the chamber dimensions. Thus my use of as good as it gets.

As to test results which is another can of worms. Anyone who has actually performed actual testing I believe what Jmorris was after was the procedure, method and equipment used. All of which are as important as the data sheet with the results. The conditions under which a test was performed? The equipment used? The well defined method as in a step by step procedure applied? What that means is if I post that I tested my rifles or let's say a load chamber pressure as 60,000 psia and let it go at that my data is as useless as teats on a bull. If I can't define how I did the test, what equipment I used, and the conditions under which the test was done all I have is questionable numbers to toss out and see who believes me. Anyone with sense will question me and I should be able to provide answers or a source of answers to their questions or I can just go home.

Thank You
Ron

F. Guffey · May 22, 2019, 04:51 PM

Quote:

f I can't define how I did the test, what equipment I used, and the conditions under which the test was done all I have is questionable numbers to toss out and see who believes me. Anyone with sense will question me and I should be able to provide answers or a source of answers to their questions or I can just go home.

And you did it all by yourself with out help from anyone.

F. Guffey

F. Guffey · May 22, 2019, 04:54 PM

and then there are fire formers and there are case formers, it is not necessary for a case former to make that first trip to the rang because he forms first and then fires.

F. Guffey

Bart B. · May 22, 2019, 05:02 PM

Quote:

Originally Posted by Reloadron

Finally, with my case held to the bolt face by the extractor, regardless of extractor clearance,

This happens when the round fires? How?

Based on the case and chamber dimensions given, there will be about .002" space between bolt face and case head when the primer starts being dented any significant amount. Primers need to be dented about .015" to .020" to fire.

Reloadron · May 22, 2019, 05:13 PM

Yes, in the real world it happens. Now if you have a reply I would be interested in hearing it? Feel free to address things one by one. No nonsense, just credible factual information. I clearly presented what I have. I call BS on some of what you posted. I clearly stated why.

Look Bart, while I have tremendous respect for your match career and even the Navy Team as a former Marine when I disagree I call BS so the ball is in your court. Got anything better than "This happens?" because yes, it happens exactly as I described, over and over again.

Thank You
Ron

Bart B. · May 22, 2019, 07:21 PM

Quote:

Originally Posted by Reloadron

Yes, in the real world it happens. Now if you have a reply I would be interested in hearing it? Feel free to address things one by one. No nonsense, just credible factual information. I clearly presented what I have. I call BS on some of what you posted. I clearly stated why.

Look Bart, while I have tremendous respect for your match career and even the Navy Team as a former Marine when I disagree I call BS so the ball is in your court. Got anything better than "This happens?" because yes, it happens exactly as I described, over and over again.

Thank You
Ron

What is the minimum clearance from your bolt face to extractor pushed back towards the bolt face?

What is the maximum rim thickness on your cases?

cw308 · May 22, 2019, 07:44 PM

I never measured the wiggle room between my bolt face and the extractor and with the case in place . Plus the difference in that extractor grove on the case , these would all come into play . Without getting all Rodney King , it's good to share ideas

jmorris · May 23, 2019, 08:22 AM

Quote:

Anyone who has actually performed actual testing I believe what Jmorris was after was the procedure, method and equipment used. All of which are as important as the data sheet with the results. The conditions under which a test was performed? The equipment used? The well defined method as in a step by step procedure applied? What that means is if I post that I tested my rifles or let's say a load chamber pressure as 60,000 psia and let it go at that my data is as useless as teats on a bull. If I can't define how I did the test, what equipment I used, and the conditions under which the test was done all I have is questionable numbers to toss out and see who believes me.

Exactly. If one were to lay out all of the parameters, procedures and tools it would be easy for another to duplicate the results and prove or disprove the data.

Alas, I don’t think that’s the goal, seems like the thread was just put here as a pot to stir.

F. Guffey · May 23, 2019, 08:48 AM

Quote:

I never measured the wiggle room between my bolt face and the extractor and with the case in place . Plus the difference in that extractor grove on the case , these would all come into play . Without getting all Rodney King , it's good to share ideas

Bart B. claims he can measure clearance no matter where it is and I say anyone that can measure clearance in front of the case shoulder or between the bolt face and case head can measure the length of the chamber from the shoulder of the chamber to the bolt face.

Quote:

these would all come into play

As I have said before; when the bolt closes the chamber gets dark and then the light goes out

. In my opinion reloaders are struggling with events and conditions they can do nothing about.

One more time; I have said there has to be something about the sequence of events that take place between pulling the trigger and the bullet leaving the case that reloaders do not understand. Bart B. claims his cases shorten between the shoulder of the case to the case head as much as .005" from the impact of the firing pin

. In the (normal) perfect world there would be .005" clearance before the trigger was pulled. For those that can keep up that is .010" clearance. Again for those that struggle to keep up that is .001" more clearance that a no go-gage length chamber if the case is full length sized to minimum length..

If all of that clearance is between the case head and bolt face when fired the case will have no option but to stretch between the case head and case body.
And the mind boggling thing? The case length from the shoulder to the case head got longer but the case shoulder did not move, and then it gets more mind boggling; even if the clearance was between the shoulder of the case and chamber shoulder when fired the shoulder still does not move.

Because the chamber got dark when the bolt closed you guys can not figure where the slack is

.

F. Guffey

F. Guffey · May 23, 2019, 08:53 AM

Quote:

Alas, I don’t think that’s the goal, seems like the thread was just put here as a pot to stir.

No, I disagree. It is about those that do not know and are afraid someone else does.

And that reminds me:

Jimmy Dean was trying to explain to his fans why the chicken crossed the road; he claimed the chicken crossed the road to show the opossum it could be done.

F. Guffey

F. Guffey · May 23, 2019, 09:07 AM

Quote:

This happens when the round fires? How?

Based on the case and chamber dimensions given, there will be about .002" space between bolt face and case head when the primer starts being dented any significant amount. Primers need to be dented about .015" to .020" to fire.

And again; Bart B. left out part of the sequence that takes place between pulling the trigger and the bullet leaving the case. Many years ago reloaders used a cartoon illustration that was supposed to answer all the questions.
That was back when reloaders though the datum was a line because of another flawed illustration.

F. Guffey

HiBC · May 23, 2019, 09:09 AM

MrGuffey,when do you lay out your methodology,processes,data,etc so other folks can repeat your experiments?

Reloadron · May 23, 2019, 11:19 AM

Bart:

Quote:

What is the minimum clearance from your bolt face to extractor pushed back towards the bolt face?

What is the maximum rim thickness on your cases?

1. Would be 0.065"
2. Average of 10 WCC 10 is 0.060"

It's all moot as my firing pin is not driving my case any further than the extractor hanging on to it will allow and my headspace in my chamber on this rifle is 1.632" so bolt face to chamber shoulder datum is 1.632". I already defined firing pin protrusion and chamber headspace. So your point is?

Ron

Bart B. · May 23, 2019, 11:59 AM

Quote:

Originally Posted by Reloadron

Bart:

1. Would be 0.065"
2. Average of 10 WCC 10 is 0.060"

It's all moot as my firing pin is not driving my case any further than the extractor hanging on to it will allow and my headspace in my chamber on this rifle is 1.632" so bolt face to chamber shoulder datum is 1.632". I already defined firing pin protrusion and chamber headspace. So your point is?

Ron

Thanks for those dimensions. What is the extractor's maximum clearance from the bolt face with just the back inch of a case chambered?

I ask to learn where the forward limit of chambered case rim movement from firing pin impact is.

F. Guffey · May 23, 2019, 01:36 PM

Quote:

MrGuffey,when do you lay out your methodology,processes,data,etc so other folks can repeat your experiments?

When? I am conserved about after. How long will it take for them to forget where the information came from? At one time I did not care.

F. Guffey

cw308 · May 23, 2019, 01:46 PM

From reading the posts , Ron's chamber measurements for his 308 and sizing to no more then .002 case headspace is exactly what mine is . The question of forward case movement would be .002 as long as the extractor allows. Where is this going and does it matter in any way.

Reloadron · May 23, 2019, 02:26 PM

Quote:

Thanks for those dimensions. What is the extractor's maximum clearance from the bolt face with just the back inch of a case chambered?

I ask to learn where the forward limit of chambered case rim movement from firing pin impact is.

Well you got me on that? I no longer have access to the tools I would need to get that dope.

Ron

View Poll Results: Where's the case head when rounds fire?
Against/touching the bolt face as the extractor holds it there.	15	35.71%
Some thousandths off the bolt face; the difference between case and chamber headspacing references.	27	64.29%
Voters: 42. You may not vote on this poll

May 22, 2019, 12:57 PM	#104
stinkeypete Senior Member Join Date: July 22, 2010 Location: Madison, Wisconsin Posts: 1,292	It will be driven forward until the the force of the rim engaging the extractor(s), friction along the case walls, or the chamber against the case shoulder exert an equal opposite force... assuming the 500 grain case moves before my mighty dollop op 10 grains of Unique goes “boom” at something like 1200 FPS in between the firing pin and the shoulder of the cartridge and the brass doesn’t swell in the chamber. Is a firing pin really 2.5 ounces in a rifle? I guess I need to take my bolt apart. As it’s a Rem model 30, I bet it’s been 100 years. I see why twin extractors might be a feature now.

May 22, 2019, 04:30 PM	#109
Reloadron Senior Member Join Date: June 8, 2016 Location: Cleveland, Ohio Suburbs Posts: 1,750	OK, I have a question. Way back in post #55 I posted the chamber specifications, well the headspace dimension of one of my .308 Winchester bolt guns. The chamber headspace dimension is 1.632". The bolt will close, albeit with some minor effort on a 1.632" headspace gauge but will not close on a 1.633" headspace gauge. That tells me that my chamber, bolt face to shoulder datum is 1.632" and that is as good as it gets. The firing pin protrusion on this rifle is 0.060" and I admit I haven't a clue what the spring tension is or the travel distance of the firing pin is or for that matter how much the firing pin weighs so I can do any velocity times mass nonsense to derive the force with which the firing pin actually strikes the primer with. I can tell say with authority that when that sucker hits the primer there is a bang. How close to my bolt face is my case head? Well not sure about that but I can with authority tell you it sure as heck can not exceed 0.002". Finally, I can also say with certainty, that if I remove a once fired case from this rifle which went in the rifle with a 1.630" measurement from case head to shoulder datum it will measure, case after case at 1.631" (approximately). Approximately means maybe +/_ 0.0005". I can say with certainty that if I deprime those cases and put in a new primer, seated 0.003" to 0.005" below the case head I can chamber and pop those primers all day long and that case will never grow. Matter of fact if I resize those cases to 1.630" and do the same thing, including trim to a nominal 2.005" nothing is going to change.A primer pops in a wide open case and what little gas there is exits the open muzzle. Finally, with my case held to the bolt face by the extractor, regardless of extractor clearance, and distance between case shoulder and chamber shoulder can never exceed 0.002". That is as good as it gets. There is no way the case can grow in a bolt gun to exceed the chamber dimensions. Thus my use of as good as it gets. As to test results which is another can of worms. Anyone who has actually performed actual testing I believe what Jmorris was after was the procedure, method and equipment used. All of which are as important as the data sheet with the results. The conditions under which a test was performed? The equipment used? The well defined method as in a step by step procedure applied? What that means is if I post that I tested my rifles or let's say a load chamber pressure as 60,000 psia and let it go at that my data is as useless as teats on a bull. If I can't define how I did the test, what equipment I used, and the conditions under which the test was done all I have is questionable numbers to toss out and see who believes me. Anyone with sense will question me and I should be able to provide answers or a source of answers to their questions or I can just go home. Thank You Ron

May 22, 2019, 04:54 PM	#111
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	and then there are fire formers and there are case formers, it is not necessary for a case former to make that first trip to the rang because he forms first and then fires. F. Guffey

May 22, 2019, 05:13 PM	#113
Reloadron Senior Member Join Date: June 8, 2016 Location: Cleveland, Ohio Suburbs Posts: 1,750	Yes, in the real world it happens. Now if you have a reply I would be interested in hearing it? Feel free to address things one by one. No nonsense, just credible factual information. I clearly presented what I have. I call BS on some of what you posted. I clearly stated why. Look Bart, while I have tremendous respect for your match career and even the Navy Team as a former Marine when I disagree I call BS so the ball is in your court. Got anything better than "This happens?" because yes, it happens exactly as I described, over and over again. Thank You Ron

May 22, 2019, 07:44 PM	#115
cw308 Senior Member Join Date: September 2, 2010 Location: Plainview , Long Island NY Posts: 3,863	I never measured the wiggle room between my bolt face and the extractor and with the case in place . Plus the difference in that extractor grove on the case , these would all come into play . Without getting all Rodney King , it's good to share ideas

May 23, 2019, 09:09 AM	#120
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,283	MrGuffey,when do you lay out your methodology,processes,data,etc so other folks can repeat your experiments?

May 23, 2019, 01:46 PM	#124
cw308 Senior Member Join Date: September 2, 2010 Location: Plainview , Long Island NY Posts: 3,863	From reading the posts , Ron's chamber measurements for his 308 and sizing to no more then .002 case headspace is exactly what mine is . The question of forward case movement would be .002 as long as the extractor allows. Where is this going and does it matter in any way.