|
Forum Rules | Firearms Safety | Firearms Photos | Links | Library | Lost Password | Email Changes |
Register | FAQ | Calendar | Search | Today's Posts | Mark Forums Read |
|
Thread Tools | Search this Thread |
November 26, 2018, 12:30 PM | #26 | |
Senior Member
Join Date: December 10, 2012
Posts: 6,161
|
Quote:
|
|
November 26, 2018, 12:47 PM | #27 | |
Senior Member
Join Date: March 1, 2009
Posts: 4,232
|
Quote:
__________________
“How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek |
|
November 26, 2018, 02:14 PM | #28 | |
Senior Member
Join Date: July 18, 2008
Posts: 7,249
|
Quote:
Now; had he asked me to bring something that would correct run out/wobble or cases that ran around in a circle as thought they were cammed I would have told him we will make one of those tools when I get there. I like the one about the bill the old retired electrician sent to his former employer. The bill was #5,000.00 dollars for 4 hours of work including travel time. His old boss was not happy and asked him to justify the bill; he explained to his boss it was not so much about 'the fixing' but knowing what to fix. F. Guffey Last edited by F. Guffey; November 28, 2018 at 08:52 AM. Reason: Not so much about the hammering, it has to do with knowing where to hammer |
|
November 26, 2018, 08:23 PM | #29 |
Staff
Join Date: March 4, 2005
Location: Ohio
Posts: 21,022
|
As long as the amount of interference fit is within the springiness (elastic) range of the brass in both the annealed and the work-hardened cases, there won't be a difference in how hard it hangs onto the bullet because the modulus of elasticity is the same for hard and soft brass.
Tension refers to tensile stress normal to the inside surface of the neck which is measured in pounds per square inch. You can work it out as hoop stress going backwards from the strain. But nobody worries what that is in a neck because even if you did know, all you could do with it is multiply it by the square inches of contact with the bullet and then by the coefficient of friction to calculate bullet pull in pounds, and given brass alloy variations and carbon deposits and lube traces, it is more sensible to just measure the seating force as you load. I have a commercial instrument that does that (RSI Load Force), but you can put a strain gauge on your press and use a load cell readout to do the same thing.
__________________
Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle |
November 26, 2018, 08:56 PM | #30 |
Senior Member
Join Date: March 21, 2012
Location: Connecticut
Posts: 2,378
|
Unclenick the way i read this is by minimizing the amount of sizing you increase your odds of being within the modulus of elasticity and therefore increase your consistency. Hence light neck tension better accuracy in theory
|
November 26, 2018, 09:35 PM | #31 | |
Senior Member
Join Date: March 1, 2009
Posts: 4,232
|
Quote:
In Chapter 6 tests .223, .243, and .308 using .001 and .003 neck tension. In .223 and .243 the velocities were much more consistent with more neck tension and in .308 there was no difference at all. I had similar results when I experimented with .223 and .260 and have settled on .003 neck tension
__________________
“How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek |
|
November 26, 2018, 09:57 PM | #32 |
Senior Member
Join Date: March 21, 2012
Location: Connecticut
Posts: 2,378
|
dawg not having read the book...
I should have qualified my comments. If brass was new or perhaps 1x fired the modulus of elasticity would be larger than if he were on say the 4 or 5th firing (if i understand nicks post properly) over the long haul the modulus of elasticity shrinks and those same rounds w .003 of neck tension may not perform the same way due to springback, or inconsistent neck tension. |
November 26, 2018, 11:02 PM | #33 |
Senior Member
Join Date: March 1, 2009
Posts: 4,232
|
Just my opinion here but I think we sweat too many things unless we are serious bench rest shooters trying to turn .15 groups into .10 groups. My gun and ammo are much better than I am at my current shooting skill level.
I shot a personal best of 198 this weekend with a group that measured 1.12 MOA across. It wasn't the ammo that limited me nor was it the rifle. It is my wind and mirage skills and my shooting technique. I had a .6 vertical https://imgur.com/yaJWuj8 to put that target in perspective there were 4 clean 200's shot at the same match and several shooters scored double digit X counts
__________________
“How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek Last edited by hounddawg; November 26, 2018 at 11:07 PM. |
November 27, 2018, 12:05 AM | #34 |
Senior Member
Join Date: November 8, 2010
Location: WISCONSIN
Posts: 283
|
I made my seating die using the chamber reamer. I insert brass case in shell holder after powder of course, set projectile on top, raise case until it just touches shoulder inside die. Then I use lever on top of press to seat projectile to proper depth. Die is made to exacting tolerances to minimize run-out.
__________________
OldmanFCSA = "Oldman" at www.fcsa.org FCSA Member, SCSA Member, NRA Member, & AMA Member "Oldage & Treachery will overcome Youth & Skill" |
November 27, 2018, 02:31 PM | #35 | |
Staff
Join Date: March 4, 2005
Location: Ohio
Posts: 21,022
|
Quote:
The thing that changes as the brass work-hardens is its tensile strength which determines the amount of pressure that must be applied to the metal's cross-section to make it yield (take a permanent bend). In other words, how big the percent of stretch is that you can apply to the metal and still have it spring back against the bullet is greater with the work-hardened neck than for a softened neck. It's the difference between a piece of soft metal that bends easily and the same metal hardened to spring temper which lets it bend considerably further before taking a permanent bent. Too hard, and you get into brittleness, but that's getting beyond the scope of what we are dealing with here. The above is why, ideally, annealing is taken just far enough to stress-relieve the brass, but not far enough to soften it much. You want tighter fitting necks to hold on harder and not to start taking a set at a wider percent of stretch. Harder hold on the bullet raises the starting pressure of a cartridge, the same as crimping does. Raised start pressure gives the powder more time to get its pressure up enough for the burn to be consistent.
__________________
Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle |
|
November 27, 2018, 03:23 PM | #36 |
Senior Member
Join Date: March 21, 2012
Location: Connecticut
Posts: 2,378
|
Thanks again for the explanation unclenick.
|
November 27, 2018, 04:07 PM | #37 |
Senior Member
Join Date: March 1, 2009
Posts: 4,232
|
Thanks again Nick, that explanation of annealing makes perfect sense. Also it makes it clear why a "perfect" anneal is not necessary as long as one does not go to extremes.
__________________
“How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek |
November 28, 2018, 09:19 AM | #38 | |
Senior Member
Join Date: July 18, 2008
Posts: 7,249
|
Quote:
And then there is time and pressure, as I mentioned earlier at 'the arsenal', they got up to 600 pounds of bullet hold. THAT HAD TO BE 'BEFORE THE INTERNET' after the invention of the Internet they would have called it neck tensions with no way to convert to pounds. Again, I settled on a method and or techniques for annealing: I gleaned through some information looking for rules that would apply to annealing. After I decided on a few rules I made a tool for annealing that agreed and or did not violate the rules of annealing. F. Guffey |
|
November 28, 2018, 09:26 AM | #39 | |
Senior Member
Join Date: July 18, 2008
Posts: 7,249
|
Quote:
F. Guffey |
|
November 28, 2018, 10:06 AM | #40 |
Staff
Join Date: March 4, 2005
Location: Ohio
Posts: 21,022
|
Yes. Time changes things, though the aged military ammo Hummer70 pulled at 600 pounds was crimped.
__________________
Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle |
November 28, 2018, 10:18 AM | #41 |
Senior Member
Join Date: March 1, 2009
Posts: 4,232
|
I spent a good portion of the morning doing some basic research on ductility and elasticity and came to the conclusion that annealing does nothing to affect elasticity of the brass only the ductility because elasticity is at the atomic level where cold working only affects the brass at a crystiline level. While annealing can prevent neck splitting it will have no effect at all on neck tension.
Not a lot of fun learning my $300 Anealeeze is nothing more than a paperweight but life could be worse, I could have dropped a grand on a AMP Now the good news for forum members is that temperature does affect the modulus of elasticity so there is a whole new batch of pins for the angels to tango on. That would mean the ammo, barrel and chamber temp will affect neck tension to a minor degree... I will just sit back and munch some popcorn while that sinks in sources- https://www.uni-ulm.de/fileadmin/web...plasticity.pdf http://www.virginia.edu/bohr/mse209/chapter6.htm https://www.quora.com/Whats-the-diff...and-elasticity https://engineering.stackexchange.co...work-hardening
__________________
“How do I get to the next level?” Well, you get to the next level by being the first one on the range and the last one to leave.” – Jerry Miculek Last edited by hounddawg; November 28, 2018 at 10:31 AM. |
November 28, 2018, 10:24 AM | #42 | |
Senior Member
Join Date: July 18, 2008
Posts: 7,249
|
Quote:
And there is always a chance when the case is held by the rim with a shell holder and or extractor the rim is damaged when the case locks up in a die and or chamber. And then there is removing the bullets by firing. F. Guffey |
|
Thread Tools | Search this Thread |
|
|