adjusting coal to the lands "methods"

. Lastly, if you jam, drop your powder charge back 1 full grain.

good advice. Yesterday I did a 4x4 load test, on the lands test the bullet picked up over 30 FPS which I would assume would relate to pressure. I did the lands test at 43.5 which is what Hogdon says is minimum load and I stopped a couple of gns below max on the charge test. On the initial 4 round pressure test I seated the bullets at .025 off
 

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Wish I could go beyand 600 yards , ranges in my area max. is 200 yards . I only shoot 200 yards with a mild load and a .002 jump , one day I will give the better brass a try but at my distance may not make much of a change . Tried different neck tension .001 and up didn't see much of a change , went back to the standard non bushing die with .003 - 4 neck tension . When I found that cases weren't all the same thickness's and I use brass that is on the thick side , I did drop the listed powder charge by one grain. It's nice to be able to shoot different long distances , not in the cards for me , 200 yards is still enjoyable

hounddawg
Nice test chart , my handwriting isn't so neat or I'd post mine , what's the saying ," can't teach an old dog new tricks"
 
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Ordered a go gauge to check the chamber with a stripped bolt on my Rem.700 308 , the 1.630 go gauge and a .002 shim my bolt closed with the slightest resistance . From there I full sized my cases to 1.631 to 1.630 no more or less

I waited and no one ask; "What does that mean?" So? I will; "What does that mean?"

F. Guffey
 
Guff
I was reading about go and no go gauges , ordered one to check my RCBS Precision Mic and chamber , bolt closed fine Mic was off , anyway I thought why not see what the chamber measurement would be by stripping the bolt to the housing for a better feel and by adding shims could see how long my chamber was . With the gauge being 1.630 with a .002 shim on the bolt face my bolt closed with the slightest resistance . Wouldn't that give me the chamber length from shoulder to bolt face ? That's what I was looking for .
 
check my RCBS Precision Mic and chamber , bolt closed fine Mic was off

The bolt closed fine; I would say the chamber is longer than a go-gage length chamber from the shoulder to the bolt face. You added a .002" shim between the head of the gage and bolt face; and then the bolt closed with slight resistance. I would suggest the chamber is .0065" longer than a minimum length/full length sized case from the shoulder of the chamber to the bolt face.

If you knew your way around 'the datum' you could have verified the go-gage. If you could verify a head space gage you could verify your fired cases; after firing and again after sizing.

And if we were not on the Internet I would ask you when you decided to purchases a head space gage you purchases a go-gage length gage instead of one of the longer ones?

F. Guffey
 
well CW I used my Go gage to set up my .260 barrels to the same headspace and now compare the gage measurements to my sized case measurements and it seems to work well for me. I set the barrels to the gage length and back off .003 using shims between the bolt and the gage. I then adjust the sizing die to the gage length which gets me .003 on the closed bolt. I get good case life (10 + reloadings) and get good accuracy. Bonus is I can take a fired case from either rifle and chamber it in the other with no bolt resistance if I ever decide to go back to neck sizing and use the same cases in both rifles.

If you adjust your FL sizing die to the gage that should give you .002 clearance the way I see it.
 
If you adjust your FL sizing die to the gage that should give you .002 clearance the way I see it.

And someone should ask; "How could that be?" I do not assume a reloaders sees it and understands it.

I just informed CW308 the full length sizing die sizes cases to minimum length/full length size. Meaning if the reloader could verify the die with a go-gage he would he would have to understand the difference in length between the chamber, case and die.

And then there are all of those boring details like from the shoulder to the bolt face, from the shoulder to the case head and all of those dimensions that are up inside the chamber die and gage.

Again, this stuff does not lock me up so if I wanted to verify the die with a head space gage I would remove the primer punch/neck expander assemble from the die and then place the go-gage into the die with the big end of the gage protruding from the shell holder of the die.

To verify measure the head space gage protrusion from the die; the protrusion should be the difference in length between a go-gage length chamber and a minimum length/full length sized case.

When the ram is raised and the bottom of the die contacts the top of the shell holder: That is it, the distance from the deck of the shell holder to the shoulder of the die can not get closer, there is no way the reloader can crush the die to reduce the length of the case. I can because I use feeler gages to raise the case head up and off of the deck of the shell holder, that is another way I increase the presses ability to overcome the cases ability to be sized.

F. Guffey

So; when I verify a 30/06 sizing die with a go-gage I measure the go-gages protrusion from the die. In the perfect world the protrusion will be .005".

And then if I decide to determine the winner when sizing I remove the die from the press before lowering the ram. In the perfect world and if the press won the case will protrude from the die .005". And then there is the gap between the bottom of the die and top of the shell holder; if there is a gap the case won, if there is no gap the press won if the die was adjusted to the shell holder for full length sizing to minimum length.
 
dawg
That's what I do , I never changed my own barrel but I understand the process . My chamber is .002 longer then the gage . Thanks again .

Chris
 
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F.Guffey
I will try the Go Guage in the press , something else to try . My way of checking the chamber , just bare in mind I'm not as well rounded as you but does it make sense using the closed bolt with the Guage and a shim to find the chamber length from bolt face to shoulder . With the lack of experience and tools I try my best with what I have . I try to keep it simple but as accurate as possible . Thank for helping .

Chris
 
dawg
That's what I do , I never changed my own barrel bbut I understand the process . My chamber is .002 longer then the gage .

.002" longer than the gage; WHY? .002" longer than the gage is a long chamber. 'HOW LONG?' .002" longer than the gage is a chamber with a built in clearance of .007".

What would I do if I had one of those chambers? When sizing cases for that chamber I would add a .005" shim between the bottom of the die and top of the shell holder OR I would use a Redding competition shell holder between number #4 and #6. I have one of those rifles that has a chamber that is .016" longer than a minimum length/full length sized case, that would be .002" longer than a field reject length case of a .011" longer than a go-gage length chamber.

When sizing cases for that chamber I adjust the die off the shell holder .014", for those that can keep up that gives me the magic .002". AND! I use 280 Remington cases, how can I miss? The 280 Remington case is longer than the 30/06 case from the shoulder to the case head. And no, the shoulder can not be moved back, as we all should know moving the shoulder back is impossible when using a die that has full body support.

F. Guffey
 
And no, the shoulder can not be moved back, as we all should know moving the shoulder back is impossible when using a die that has full body support.

Only in your world, F. Guffey, only in your world.

Don
 
And no, the shoulder can not be moved back, as we all should know moving the shoulder back is impossible when using a die that has full body support.

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Only in your world, F. Guffey, only in your world.

Just in case there is a reloader that has the ability to be curious but does not know what question to ask USSR why he would choose to be so rude. And then someone could ask if the shoulder does not move back when sized what happens to it? Or they could ask If 'MY' shoulder does not move back what happens to it when I form and or size a case with a die that has case body support?

Or someone could ask "what is it that is so confusing for reloaders to understand about sizing the case that makes it impossible for them to understand?" I will suggest many of them are just hard headed and then others are 'siders'. Siding is a mountain thing, The Hatfield and the McCoy's were siders, they were on opposite sides.

Not me; as I have suggested to reloadrs that do understand the shoulder can not be move back and it is impossible to bump the shoulder back, scribe the case body/shoulder juncture before sizing and or forming the case. I found the scribe line never moves back. When scribing the line I have found the shoulder that is created when forming and or sizing is a new shoulder and more times than not I found my old shoulder did not move.

And when heavy forming I found my 'old' shoulder became part of the shoulder/neck.

And then there is 'bump', that would be a function of the cam over press; the non cam over press is not a bump press. But to some everything is bump.

F. Guffey
 
And no, the shoulder can not be moved back, as we all should know moving the shoulder back is impossible when using a die that has full body support.
Only in your world, F. Guffey, only in your world.
Don

When a case goes into a FL or Body die it is basically being cold forged and the brass reshaped. Now in my world brass flows under pressure, and like any other material will travel in the path of least resistance. That's how and why case necks lengthen and also why you get thin brass at the shoulder/body or at the end of the web where it goes into the main body and have case separations. You know the thin spots that you look for with a bent paperclip. That brass went somewhere too. It is also the reason that neck walls get thicker after several firings and why I do a inside neck ream after a case is has had it's 5th firing
 
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F.Guffey
I'm confused , .002" longer then the gage is a built in chamber clearance of .007 when I ordered the go gage my thinking is by adding shims I would know the chamber measurement from the shoulder to the bolt face , by adding the .002 shim making my chamber 1.632 , adding a ..003 shim it would be a no go , my way of thinking . I'm lost with the clearance of .007 Sorry
What headspace gage do you use , I thought the go gage could be used as one . I didn't try it in my die yet . I would think a .002 shim in the shellholder would bottom like my bolt when set up in the press regular shellholder ram raised , lower full length die to shellholder with no flex .

PS I tried the go gage in my F/L die with die bottomed on shellholder and the go gage seated with no room between gage and shellholders lower base or die and shellholder . It's a RCBS Standard Full length die nothing fancy . Thank you for answering.

Chris
 
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Now in my world brass flows under pressure, and like any other material will travel in the path of least resistance. That's how and why case necks lengthen...

Exactly.

Don
 
Right, and I believe that is Mr. Guffey's point when he says you don't move a shoulder back. The sizing die is actually an extrusion die, flowing the top end of the shoulder into the neck, and the top end of the case body into the shoulder. Thus, the shoulder brass doesn't actually relocate down to original position, it gets displaced.


CW308,

Mr. Guffey's point is that if you set a shell holder on your bench and then put a GO gauge in the shell holder and rest an FL sizing die on the protruding part of the GO gauge, there should be a 0.005" gap between the mouth of the die and the deck of the shell holder. This is because sizing dies have to be made short to allow for case spring-back in a case fired in a long chamber. I've resized cases fired in heavily worn club Garands, some undoubtedly near military Field Reject chamber length (which is longer than commercial Field Reject) and seen as much as 0.005" difference in the head-to-shoulder lengths of their cases after a single trip through the sizing die. So it makes sense for die makers to build that much extra squeeze into them.

It is also because conventional wisdom is that, especially for self-loading guns, you want the shoulder datum to wind up about -0.002" shorter than minimum chamber length to ensure reliable feeding in a minimum chamber. If you measure new commercial ammunition, is usually has 1.627-1.628" head-to-shoulder datum length, which is shorter than a minimum chamber headspace by -0.003" and -0.002", respectively. If I had one of the aforementioned long-chamber Garands, I would not try to get there. Just extruding the shoulder enough that the datum diameter measures -0.002" shorter than it was as-ejected by firing would be good enough.


Touching the lands

There is a persistent belief that touching the lands causes a sudden jump in pressure. This is not accurate. The late Dr. Lloyd Brownell measured the effect and found pressure increased as you got near the throat, so being 0.002 off the lands does not make pressure appreciably lower than kissing the lands does. But by the time you are 0.030" off the lands with a tangent ogive bullet, you see about 20% difference in chamber pressure. (QuickLOAD's recommend start pressure allowance puts it more like 18% greater, so I figure that's pretty average.)

attachment.php


What Dr. Brownell did was use a round nose bullet to make his measurements. The round nose has a very gradual taper from the shoulder (forward end of the cylindrical bearing surface) to the hemispherical nose. That means the annular gap between the bullet and the outside of the freebore increases in area very gradually as you seat the bullet deeper. The fact he had to move this bullet much deeper to get a change in peak pressure than you do with a spitzer nose bullet, which increases the annular gap much more for each increment of greater seating depth, caused him to conclude it is the amount of gas bypassing the bullet into the bore after the case neck expands and before the bullet moves forward to obturate (seal or block off) the bore that was causing the change in pressure rise and its final peak value.

attachment.php


So, while the amount of bullet jump you need with a spitzer nose to reach the minimum in your gun's pressure vs. seating depth curve will be much less than the quarter inch the gradually tapered round nose required in that plot, and while your pressure difference will likely be a larger percentage than for the round nose, nonetheless, seating just a thousandth or two back won't get you much less pressure than jamming does because the not much gas will bypass the bullet before it moves that short distance forward.
 
Not sure I know what any of this has to do with seating the bullet! Seem's to me that no matter how long or short the case may be, if it will chamber, it won't matter how deep the bullet is seated, it'll still be the same won't it? Measuring the case is about fitting it to the chamber, not the lands.
 
Thus, the shoulder brass doesn't actually relocate down to original position, it gets displaced

and the difference between displacing and relocating is ?

to move to a new location

https://www.merriam-webster.com/dictionary/relocate

: to move physically out of position

https://www.merriam-webster.com/dictionary/displace


as near as I can tell Mr Guffy has no idea on what happens to the brass inside the die when full length sizing

Not sure I know what any of this has to do with seating the bullet! Seem's to me that no matter how long or short the case may be, if it will chamber, it won't matter how deep the bullet is seated, it'll still be the same won't it? Measuring the case is about fitting it to the chamber, not the lands.

oh but Don the case might move .003 inches inside the chamber when the bolt closes....not that it makes a rats ass worth of difference on paper when you are at the shooting bench
 
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Don Fisher said:
Seem's to me that no matter how long or short the case may be, if it will chamber, it won't matter how deep the bullet is seated, it'll still be the same won't it?

Not unless you mean the COL stays the same. If it does not, the pressure will change (see the graphs), so velocity and the barrel time important to a good sweet spot will change as well.
 
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Thus, the shoulder brass doesn't actually relocate down to original position, it gets displaced

and the difference between displacing and relocating is ?

We are back to doing the semantics dance.:D

Don
 
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