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May 14, 2015, 08:50 AM   #26
F. Guffey
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Join Date: July 18, 2008
Posts: 6,783
Quote:
 I'm pretty sure that the inertia of the cartridge is enough to allow the firing pin to crush the primer, especially with the speed of a typical bolt action firing pin. __________________
My firing pins are killer firing pins, they crush the primer before the case, powder and bullet know their little buddy, the primer, has been crushed.

F. Guffey

May 17, 2015, 11:28 AM   #28
44 AMP
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Location: Upper US
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Quote:
 I'm pretty sure that the inertia of the cartridge is enough to allow the firing pin to crush the primer, especially with the speed of a typical bolt action firing pin.
I disagree. Something has to hold the case "in place", I don't think inertia alone is enough. This is going to be either what ever point the case "headspaces" on, OR is going to be the extractor, in most cases.

Also, the inertia of a round is going to vary with the mass of the round.
Smaller cases are going to have less inertia.

The pressure of a firing pin (or hammer) spring is measured in pounds, often over a dozen pounds. A loaded round weighs what? less than an ounce, usually. I just don't see inertial alone holding the case in place long enough to crush the primer.
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All else being equal (and it almost never is) bigger bullets tend to work better.

 May 17, 2015, 11:42 AM #29 F. Guffey Senior Member   Join Date: July 18, 2008 Posts: 6,783 44 AMP, 1 ounce = 437.5 grains. There are 7,000 grains in a pound. Then there is that .7854 thing, I have killer firing pins. Then there is that thing about millage. And there are variables, and there is that very boring conversation that starts with "Hatcher said". Forgive, there are factors. F. Guffey
 May 17, 2015, 12:17 PM #30 B.L.E. Senior Member   Join Date: December 20, 2008 Location: Somewhere on the Southern shore of Lake Travis, TX Posts: 2,603 The firing pin of a AR-15 weighs about 120 grains. There are titanium firing pins available that only weigh 70 grains. A .223 round with a 60 grain bullet weighs about 180 grains. Now, if that 120 grain, or even a 70 grain titanium firing pin can crush the primer with its inertia, why can't a 180 grain cartridge have enough inertia to act as an anvil? The spring does not push the firing pin into the primer. It's not nearly strong enough. Prove it to yourself. Chamber a primed case in a bolt action rifle. Lower the firing pin by holding the trigger back as you slowly close the bolt. Open the bolt. Do you see a dent in the primer? __________________ Hanlon's Razor "Do not invoke conspiracy as explanation when ignorance and incompetence will suffice, as conspiracy implies intelligence and organization."
May 17, 2015, 12:50 PM   #31
F. Guffey
Senior Member

Join Date: July 18, 2008
Posts: 6,783
Quote:
 Then there is that .7854 thing,
I am the fan of the running start, I want my bullets to have 'the jump', I do not want my bullet setting still at the rifling, I do not want my bullet setting there wondering if it is going to start moving, I want my bullets moving into the rifling before it knows it is there.

It was suggested I was wrong, seems someone Velcro-ed a case into a large chamber, closed the bolt and then pulled the trigger.

F. Guffey

May 17, 2015, 02:50 PM   #32
Metal god
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Join Date: April 10, 2012
Location: San Diego CA
Posts: 4,530
Quote:
 I am the fan of the running start, I want my bullets to have 'the jump', I do not want my bullet setting still at the rifling, I do not want my bullet setting there wondering if it is going to start
I've never understood this point ????? As soon as the cartridge is chambered the bullet is just sitting there until it's not . It's not wondering what to do .

I contend a bullet that jumps to the lands slows down if not stops when it hits the lands . Hmm that to me would be when the bullet looks back at you and asks "a what now" . Unlike a bullet jammed in the lands . If the bullet never hit a resistance point in the firing process like running square into a smaller section to squeeze into it never gets a chance to think what it's supposed to do next . It just continually goes faster and faster never getting a chance to rethink it's objective .

Now I'm in no way saying one is better then the other . Only that when jumping a bullet to the lands . That creates a secondary effect on the bullet that does not happen if the bullet is already in the lands .
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May 17, 2015, 10:42 PM   #33
F. Guffey
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Join Date: July 18, 2008
Posts: 6,783
Quote:
 I contend a bullet that jumps to the lands slows down if not stops when it hits the lands .
"jumps to the lands slows down if not stops when it hits the lands"

Jumps, slows down or stops? All that in milliseconds while the powder is burning and building pressure. And then? After stopping and or slowing down it has to start moving again.

F. Guffey

May 17, 2015, 10:52 PM   #34
F. Guffey
Senior Member

Join Date: July 18, 2008
Posts: 6,783
Quote:
 Now I'm in no way saying one is better then the other . Only that when jumping a bullet to the lands . That creates a secondary effect on the bullet that does not happen if the bullet is already in the lands
If it is already there why is it easier to get the bullet moving if the bullet is jammed into the rifling? Pressure must build to get it moving, the secondary effect will be higher.

Again, I am the fan of the running start.

F. Guffey

Same thing with the firing pin. My firing pins have the running start.

 May 17, 2015, 10:58 PM #35 Metal god Senior Member   Join Date: April 10, 2012 Location: San Diego CA Posts: 4,530 I never said it was easier just that there is no secondary action/disruption to the bullet if the bullet is already in the lands . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .
May 18, 2015, 05:25 AM   #36
F. Guffey
Senior Member

Join Date: July 18, 2008
Posts: 6,783
Quote:
 I never said it was easier just that there is no secondary action/disruption to the bullet if the bullet is already in the lands .
I have heard that, I have always said anyone that believes that has never seen a graph that reads pressure and time as in 'when it happened' and the amount of pressure created 'when it happened'. The horror story begins when the bullet stops or 'really' slows down. To get a picture of that chamber an 8mm57 round in a 30/06 chamber.

Then there was the shooter that purchased 308 Winchester ammo for a 25/06 chamber. That was in central N. Texas. He was going to sue everyone.

F. Guffey

 May 18, 2015, 08:29 AM #37 603Country Senior Member   Join Date: January 6, 2011 Location: Thornton, Texas Posts: 3,547 Consider that Weatherby cartridges require a freebore to keep pressure from spiking to dangerous levels. That backs Mr Guffey's "running start". I do not and will not knowingly jam a bullet into the lands when it's chambered. You can if you want to.
May 18, 2015, 09:59 AM   #38
Metal god
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Join Date: April 10, 2012
Location: San Diego CA
Posts: 4,530
Quote:
 That backs Mr Guffey's "running start".
I'm not sure what that is backing ? He just said he likes a running start . So do I and that was not my point . My point was VERY narrow in scope . Maybe I used the wrong term when saying the bullet slows down . Maybe a more accurate term would be that the bullet does not continue to accelerate evenly when it hits the lands .

Now it's been a couple years but I do remember reading a study or test that suggested the bullet slows or does not accelerate equally when it hits the lands from a jump . I'll try to find it .
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If Jesus had a gun , he'd probably still be alive !

I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

Last edited by Metal god; May 18, 2015 at 12:07 PM.

May 18, 2015, 11:22 AM   #39
F. Guffey
Senior Member

Join Date: July 18, 2008
Posts: 6,783
Quote:
 test that suggested the bullet slows or does not accelerate equally
I pull the trigger, after that it is out of my hands and I do not have a problem accepting the things I can not change. I do understand the things I am in control of before I pull the trigger.

There is nothing about pulling the trigger on a round with the bullet seated into the lads that impresses me. Then there is that other often repeated story about the firing pin driving everything to the front of the chamber. If the bullet is stuck into the lands and then the firing pin drives it further after the primer is struck the bullet is more stuck?

Or the bullet is driven back into the case, and that presents another problem with pressure, seating the bullet back into the case increases pressure.

F. Guffey

 May 18, 2015, 12:06 PM #40 Metal god Senior Member   Join Date: April 10, 2012 Location: San Diego CA Posts: 4,530 Yep __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .
 May 18, 2015, 04:27 PM #41 gwpercle Senior Member   Join Date: November 30, 2012 Location: Baton Rouge, Louisiana Posts: 885 I thought head space was the area under your hat !
May 18, 2015, 05:43 PM   #43
Metal god
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Join Date: April 10, 2012
Location: San Diego CA
Posts: 4,530
Quote:
 Once closed, the head space is the distance between the closed bolt's face and the head of the cartridge.
NO ! that is incorrect . Using your analogy , head space is the distance from the bolt face to where the cartridge was stopped from going in any further . 223 bolt to chamber shoulder , 9mm bolt to ridge in chamber that the case mouth stops on , 22lr is the same as all rimmed cases . This measurement ONLY pertains to areas in the chamber or between the bolt face and where a rimmed cartridge stops and has nothing to do with the cartridge it self . So on a 223/30-06 the head space would be the distance from the closed bolt face to the area of the CHAMBERS shoulder where the case would have stopped . This area of the chambers shoulder is the datum line/area . There is no line but many say line when referring to this area .
__________________
If Jesus had a gun , he'd probably still be alive !

I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

 May 18, 2015, 06:25 PM #44 sirgilligan Senior Member   Join Date: October 28, 2009 Posts: 606 Then what is the space between the case head and the bolt face called? Am I missing something? I don't know. I am talking about reloading, not setting up a rifle or re-barrelling a rifle. This means that I am working with a rifle that has been properly setup and has had the space measured from the bolt face to the point in the chamber that is used for stopping the forward motion of a cartridge. If you resize your case incorrectly and push the shoulder back to far, what have you messed up? The head space? So, again, what is it called when you do this? The space between the bolt face and the head of the case, what is that called? __________________ SirGilligan - "If you find your back is up against a wall, maybe you have been backing up for too long." iOS Apps: BallisticsGL Gun Log Gun Log SPC WatchForce
 May 18, 2015, 06:31 PM #45 603Country Senior Member   Join Date: January 6, 2011 Location: Thornton, Texas Posts: 3,547 Go back to the first part of this discussion and read what UncleNick said. Or read the Port-a-pottie analogy.
May 18, 2015, 06:46 PM   #46
Metal god
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Join Date: April 10, 2012
Location: San Diego CA
Posts: 4,530
Quote:
 Then what is the space between the case head and the bolt face called?
haha , with out trying to sound to snarky .

Its called the space between the case head and the bolt face
__________________
If Jesus had a gun , he'd probably still be alive !

I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

 May 18, 2015, 07:07 PM #47 HiBC Senior Member   Join Date: November 13, 2006 Posts: 6,173 How about head clearance?
May 18, 2015, 07:59 PM   #49
sirgilligan
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Join Date: October 28, 2009
Posts: 606
Here is an online resource, for those that don't have the same manuals. The author designates two types of head space. Chamber headspace and cartridge headspace length.

Quote:
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 May 18, 2015, 08:06 PM #50 sirgilligan Senior Member   Join Date: October 28, 2009 Posts: 606 Here is another online article that I just "re-found". I read it a while back. http://www.larrywillis.com/headspace.html "The term headspace means the "space" between the "head" of your case and the breech. This space (clearance) is set when your barrel is installed. Handloaders should minimize the chamber clearance that their handloads have in their chamber." __________________ SirGilligan - "If you find your back is up against a wall, maybe you have been backing up for too long." iOS Apps: BallisticsGL Gun Log Gun Log SPC WatchForce

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