Erik Cortina
Team Lapua Brux Borden Captain
masterblaster1 said:
Yes, the chamfer will give you a false reading.
308 Chamber headspace is 1.621, is this considered a tight chamber?
- Thread starter masterblaster1
- Start date
Yes, the chamfer will give you a false reading.
I'll give PTG a call in the morning then probably try this. Thanks for talking this through with me gents.
243winxb said:
skiutah02
Silver $$ Contributor
Thought hard about weighing in here as I might be out of turn, but fired Lapua cases from my Savage 308 FTR measure 1.622 using the Hornady gauges so 1.621 does not seem excessively tight (to me) based upon my measurements (or am I not following this thread correctly?). If I just neck size them and leave the shoulder alone, they still chamber but it is clearly a tight fit as the bolt takes more umph to close. Drew
Erik Cortina
Team Lapua Brux Borden Captain
243winxb said:
If he does this it will likely close on the no-go gauge, which is not optimum.
stool
nominal is 1.630
and he claims he is at 1.621....
with a savage, my opinion is it
a) bad assembly
less likely
b) a bad bbl
even more remote
c) a bad go-gauge...just not even probably....
do not call ptg...this is an error in assembly....
did you twist the bbl while tightening the nut ??
some one tell me i am wrong....
and he claims he is at 1.621....
with a savage, my opinion is it
a) bad assembly
less likely
b) a bad bbl
even more remote
c) a bad go-gauge...just not even probably....
do not call ptg...this is an error in assembly....
did you twist the bbl while tightening the nut ??
some one tell me i am wrong....
masterblaster1 said:
False reading - yes. Longer or shorter, well who knows? As advised earlier, get professional face to face advice. No-one can visualise your set-up from a few words on a computer screen.
Regards
JCS
I have a Benchmark 5-c barrel they chambered last year. All my .308 brass fired in this chamber read 1.625". At first I thought they'd screwed up but using a case gauge each case is "Dead On". When I check a few factory loads they read 'short' as well.
I've just accepted the fact that the Hornady Headspace gauge isn't all that accurate but's good enough to read "shoulder bump".
Factory ammo shoots just fine in this chamber so I've merely moved on to other "questions". Many of the guys I shoot with will just adjust their sizing dies using the rifle itself to check headspace. Using a fired case and a stripped bolt they size until the bolt handle close with only the very slightest drag. This is for their target rifles. If for a "Tactical" or "Hunting Rifle", just use the Hornady gauge to add another .002".
In this case I don't believe it's a case of faulty chamber measurements, just the measuring tool isn't capable of reading them accurately.
I've just accepted the fact that the Hornady Headspace gauge isn't all that accurate but's good enough to read "shoulder bump".
Factory ammo shoots just fine in this chamber so I've merely moved on to other "questions". Many of the guys I shoot with will just adjust their sizing dies using the rifle itself to check headspace. Using a fired case and a stripped bolt they size until the bolt handle close with only the very slightest drag. This is for their target rifles. If for a "Tactical" or "Hunting Rifle", just use the Hornady gauge to add another .002".
In this case I don't believe it's a case of faulty chamber measurements, just the measuring tool isn't capable of reading them accurately.
I just reinstalled the barrels, they were a bit tight so I backed off til they were two finger tight against the go gauge I will head to the range right now and report back tonight.
bigedp51
masterblaster1
I know the photos below are not for a .308 but they are the only photos I have on the subject, and you can "calibrate" your Hornady cartridge case headspace gauge to read actual headspace.
Below is a Colt 5.56 Field gauge for a AR15, at 1.4736, as assembled and attached to my vernier calipers it would read .011 shorter than what was written on the gauge itself.
Below the Colt Field gauge in my "calibrated" Hornady cartridge case gauge reading true headspace. (this digital gauge only reads to .0005 so it will not display down to the last .0001)
All I had to do to calibrate the Hornady gauge was loosen the set screw between the red and silver sections of the body of the gauge and insert a .011 feeler gauge and re-tighten the set screw. You may need to wiggle the sections and re-tighten until the gauge reads the same as the headspace gauge, unless you have three hands and a helper.
As long as your rifles bolt doesn't close on the GO gauge your chamber isn't too short. The problem most likely is caused by the plus and minus world we live in manufacturing tolerances. Meaning your resizing die and shell holder could be your problem and between the two of them they are not pushing the shoulder of the case back far enough. All you need to do in this case is lap the top of the shell holder just a few thousandths on some fine wet and dry sandpaper using a little oil for the shell holder to "float" on while lapping.
Pay attention to the illustration below and the blue, red and green dotted lines and the words "shoulder setback" in the center of the drawing. Also remember it's possible for the sizing dies to make the case "LONGER" than its fired length as the brass is squeezed inside the die and forced upward during the sizing operation.
Your shell holder is the cheapest part you have to work with and "YOU" can shorten the shell holder yourself and not pay anyone to shorten your sizing die.
The distance between a SAMMI GO and NO-GO gauge is approximately .004 and if you look at the SAAMI drawings there is .010 between min and max headspace. I have old milsurp rifles that are way over SAAMI specifications and they shoot just fine, and with stock factory dies and chamber .001 or .002 isn't the end of our plus and minus world.
I know the photos below are not for a .308 but they are the only photos I have on the subject, and you can "calibrate" your Hornady cartridge case headspace gauge to read actual headspace.
Below is a Colt 5.56 Field gauge for a AR15, at 1.4736, as assembled and attached to my vernier calipers it would read .011 shorter than what was written on the gauge itself.
Below the Colt Field gauge in my "calibrated" Hornady cartridge case gauge reading true headspace. (this digital gauge only reads to .0005 so it will not display down to the last .0001)
All I had to do to calibrate the Hornady gauge was loosen the set screw between the red and silver sections of the body of the gauge and insert a .011 feeler gauge and re-tighten the set screw. You may need to wiggle the sections and re-tighten until the gauge reads the same as the headspace gauge, unless you have three hands and a helper.
As long as your rifles bolt doesn't close on the GO gauge your chamber isn't too short. The problem most likely is caused by the plus and minus world we live in manufacturing tolerances. Meaning your resizing die and shell holder could be your problem and between the two of them they are not pushing the shoulder of the case back far enough. All you need to do in this case is lap the top of the shell holder just a few thousandths on some fine wet and dry sandpaper using a little oil for the shell holder to "float" on while lapping.
Pay attention to the illustration below and the blue, red and green dotted lines and the words "shoulder setback" in the center of the drawing. Also remember it's possible for the sizing dies to make the case "LONGER" than its fired length as the brass is squeezed inside the die and forced upward during the sizing operation.
Your shell holder is the cheapest part you have to work with and "YOU" can shorten the shell holder yourself and not pay anyone to shorten your sizing die.
The distance between a SAMMI GO and NO-GO gauge is approximately .004 and if you look at the SAAMI drawings there is .010 between min and max headspace. I have old milsurp rifles that are way over SAAMI specifications and they shoot just fine, and with stock factory dies and chamber .001 or .002 isn't the end of our plus and minus world.
stool
which gets us back to terminology...
headspace is a characteristic of the bolt face and the chamber.
stoney point and similar tools are used to measure head clearance.....how loose is the brass front to back...clearance.
as this discussion has shown , you cannot measure HEADSPACE with a stony point or similar tool.......
their inserts do not seem to line up with the reference point on the chamber drawing.
headspace is a characteristic of the bolt face and the chamber.
stoney point and similar tools are used to measure head clearance.....how loose is the brass front to back...clearance.
as this discussion has shown , you cannot measure HEADSPACE with a stony point or similar tool.......
their inserts do not seem to line up with the reference point on the chamber drawing.
bigedp51
Headspace is also the distance between your ears and how you use it. :
Setting the headspace on a Savage rifle is like adjusting the cones on a bicycle axle, if the cone moves while tightening the jam nut your bearing clearance will change. And the same applies to tightening the barrel nut and any movement between the barrel and receiver.
The SAAMI gives you a min and max of .010 for headspace, "acceptable" headspace for a new rifle gives you approximately .003 to .004 to play with between GO and NO-GO. And trying to get your headspace set as close to the minimum of the GO gauge will put you in trouble with our plus and minus world we live in.
A trip to SavageShooters forum will take you to people asking the same basic question here and why their dies do not size their cases to fit the chamber they were fired in. In every case it is because these people adjust their headspace with the shade tree tools they have at home and trying to set the headspace as tight as possible. In ever case they ask the same question, "why won't my resized cases fit in my chamber"?
Give your chamber a little breathing room for the plus and minus world we live in, you sure as shit wouldn't use these headspace setting methods on a rifle used to shoot a charging bull elephant. All it would take is some fly shit to keep the case from chambering in a rifle with the headspace set to tight, give yourself some fudge factor when setting headspace. You "ARE" going to "fireform" your cases to your chamber anyway so what is .001 or .002 breathing room going to hurt.
Behind the worlds greatest beer below is a No.4 Enfield rifle with replaceable bolt heads for adjusting headspace, this rifle pictured has had the headspace set .006 below minimum and .010 over maximum as an experiment for testing. And I can tell you once you start setting your headspace at or below minimum you will start having problems in our plus and minus world.
Below is too much headspace and the the type I worry about the most.
Setting the headspace on a Savage rifle is like adjusting the cones on a bicycle axle, if the cone moves while tightening the jam nut your bearing clearance will change. And the same applies to tightening the barrel nut and any movement between the barrel and receiver.
The SAAMI gives you a min and max of .010 for headspace, "acceptable" headspace for a new rifle gives you approximately .003 to .004 to play with between GO and NO-GO. And trying to get your headspace set as close to the minimum of the GO gauge will put you in trouble with our plus and minus world we live in.
A trip to SavageShooters forum will take you to people asking the same basic question here and why their dies do not size their cases to fit the chamber they were fired in. In every case it is because these people adjust their headspace with the shade tree tools they have at home and trying to set the headspace as tight as possible. In ever case they ask the same question, "why won't my resized cases fit in my chamber"?
Give your chamber a little breathing room for the plus and minus world we live in, you sure as shit wouldn't use these headspace setting methods on a rifle used to shoot a charging bull elephant. All it would take is some fly shit to keep the case from chambering in a rifle with the headspace set to tight, give yourself some fudge factor when setting headspace. You "ARE" going to "fireform" your cases to your chamber anyway so what is .001 or .002 breathing room going to hurt.
Behind the worlds greatest beer below is a No.4 Enfield rifle with replaceable bolt heads for adjusting headspace, this rifle pictured has had the headspace set .006 below minimum and .010 over maximum as an experiment for testing. And I can tell you once you start setting your headspace at or below minimum you will start having problems in our plus and minus world.
Below is too much headspace and the the type I worry about the most.
skiutah02 said:
My fired cases measure 1.621 with my Hornady tool also. New lapua brass measure 1.612 with the same gauge. I would suggest that the op measure new brass with the gauge and fired brass and see what the difference is.
OKay I am back from range, the cases are measuring 1.627 now, I am happy, head clearance is probably correct, I will be bumping them back to 1.625 now. I had the barrel screwed in too tight, this was the cause of a tight (shorter) head clearance. Thanks for the help here gents. The rifles shot well, not as well as before but I think when I resize this brass they will be back to normal groupings.
Erik Cortina
Team Lapua Brux Borden Captain
masterblaster1 said:
Let's hope.
bigedp51
I first read the quote "A cartridge case should fit the chamber like a rat turd in a violin case" at German Salazar's "The Rifleman's Journal". Some of you might have heard of the gentleman below and his thoughts on the subject.
My first Savage rifle was a .243 and my brand new unfired brass was .009 shorter than the GO gauge, this same .243 rifles headspace was set at almost .002 longer than the GO gauge from the factory.
And each one of the dies below will bump the shoulder back a different amount when the die makes hard contact with the shell holder. (Press cam over)
So leave a little "extra" room for rat fecal debris in your chamber just in case everything turns to shit when your reloading.
My first Savage rifle was a .243 and my brand new unfired brass was .009 shorter than the GO gauge, this same .243 rifles headspace was set at almost .002 longer than the GO gauge from the factory.
And each one of the dies below will bump the shoulder back a different amount when the die makes hard contact with the shell holder. (Press cam over)
So leave a little "extra" room for rat fecal debris in your chamber just in case everything turns to shit when your reloading.
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