Is there a tool similar to the OAL Hornady Gauge that measures your chambers exact headspace? Is the only way to know this by having a chamber cast? I have tried setting mine using a spent case and extractor/pin removed from my bolt but no matter how much bump I gave the case it had the same amount of felt tension closing the bolt. My chamber is tight. Its a .204 no neck turn 230 neck. Could the tight neck have an affect on the bolt close?
Headspace chamber tool
- Thread starter Sigfla
- Start date
RCBS Precision Mic works very well and you can measure the chamber headspace, the cartridge length at the ogive, and the case set back. How does the case feel when you full length size the case? Have you tried a factory cartridge to see if that is snug too? After using the Precision Mic I think you will have your answer.
Erik Cortina
Team Lapua Brux Borden Captain
A go gauge and tape on back. Measure gauge base to tip and then add up how much tape it took to get snug. Use blue painters tape and it will "crush" when you close bolt so you can measure.
Won't the measurement vary depending on how many times the case was fired and if you bumped the shoulder? Someone on this website said you may have to fire a new case 2-3 times before the shoulder gets pushed as far forward as it will ever get. Bumping the shoulder messes up the measurement. Do you agree that you need to fire the case several times making sure you don't bump the shoulder then take your measurement. I use Tony Boyers method to adjust the die. No reason to really know a measurement that I can think of.
I think he said a GO gauge. Tape works on a fired case also. Larry
Seems to me you solved your own problem.. Now all you have to do is find out WHERE the resistance is coming from... It's obviously NOT a tight headspace deal.. start measuring below that area and a light will come on at some point.
Good luck.
My .204 I doubt will work the brass much during firing but as long as I periodically check as they are fired several times I should know what bump I need. I used (Tony's/Broz's) method as well and it just didn't seem to change anything as far as bolt tension. I got it from Broz's U tube channel. Maybe it was b/c I was using once fired .204.
I have a Comparator already. I just watched a U tube video comparing the Mic and the Comparator. Looks like all I need to do is fire a round already setup for my gun. My tight chamber gun chambers anything with the neck at 228. Dunno what the chamber headspace is but I can measure the unfired case just for comparison to the fired. Fire the round then measure and adjust the die for whatever clearance you need 2-3 thousandths??
Rather than buying the RCBS mics, I would get ahold of an actual chamber gauge (Clymer, etc.).
You can calibrate your comparator by measuring the gauge and making a note of how far your comparator is off from actual headspace.
My 0.400" comparator bushing (for my 308) is off by about 0.006".
You can calibrate your comparator by measuring the gauge and making a note of how far your comparator is off from actual headspace.
My 0.400" comparator bushing (for my 308) is off by about 0.006".
Yeah but then don't you need a set of varying size? I might just be anal with my .204 trying to get the headspace right on. I had hoped a simple gadget was out there that offered a measurement. I like the idea of a go gauge and tape but would prefer something more precise. Seems like a go gauge with an adjustable bolt face would serve the purpose. Keep extending till it won't chamber then back off and measure.
Straighten me out on this. What difference does it matter what the head space is as long as long as you can easily chamber the round. Why is this a problem or a need for measurement? In a sense no matter what gun or case you are essentially fire forming the case. Shooting a .223 round in a .223 rifle, is it any different than firing a 6BR Norma case in a 6 BRX chamber. You size based on what you end up with.
butchlambert
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Have you considered that the base of your brass is not sized enough? I've seen a lot of brass that have had the shoulder bumped too much for the reason that you are giving. A small base die fixed the problem.
You don't need the entire set of headspace gauges to use the comparator as I described.
The comparator does not read true headspace since there's a radius machined on the opening of the bushing...it's off a few thousandths from true headspace.
If you measure a headspace gauge (with a known headspace dimension labeled on it) using the comparator, and make note of the difference (or re-zero the calipers), you have then calibrated your comparator, which will measure a true headspace dimension from fired brass.
+1 for RCBS Precision Mic. One of the barrels measure the base to shoulder height. The other measures the base to ogive length.
To check your rifle try to expand a case until it is straight with NO neck at all.
Then start resizing the case until a heavy force will start the stripped bolt to close.
You can sneak the die down .001 at time until your bolt will close with a light drag.
Your Hornady gage can now read that dimension but there will be an error due to the edge break on the bushing bore. Due to the edge break the Hornady will always give readings that are undersize unless you zero it with a gunsmith's head space gage.
If you want the exact head space number you need to set your Hornady tool with a gunsmith's .204 head space gage. The shoulder angle and the gage ring diameter has to match the SAAMI specs.
Read the number on the gage and set your caliper to exactly that number using the gunsmith gage in place of a case. Once you have the caliper set on one standard it will be accurate for the small variation that will exist between your rifle and the gunsmith's gage.
Once you get a good zero for the gage measure an old work hardened case and write the dimension on it with a permanent marker. Keep that case in your die box for setting your Hornady gage and caliper in the future. That number will only work for the exact same bushing and cases with the same shoulder angle. So it will not work with a .223.
Then start resizing the case until a heavy force will start the stripped bolt to close.
You can sneak the die down .001 at time until your bolt will close with a light drag.
Your Hornady gage can now read that dimension but there will be an error due to the edge break on the bushing bore. Due to the edge break the Hornady will always give readings that are undersize unless you zero it with a gunsmith's head space gage.
If you want the exact head space number you need to set your Hornady tool with a gunsmith's .204 head space gage. The shoulder angle and the gage ring diameter has to match the SAAMI specs.
Read the number on the gage and set your caliper to exactly that number using the gunsmith gage in place of a case. Once you have the caliper set on one standard it will be accurate for the small variation that will exist between your rifle and the gunsmith's gage.
Once you get a good zero for the gage measure an old work hardened case and write the dimension on it with a permanent marker. Keep that case in your die box for setting your Hornady gage and caliper in the future. That number will only work for the exact same bushing and cases with the same shoulder angle. So it will not work with a .223.
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You can load a case easy and have the head space be wrong . Blowed primers are common whe the case closes easy . Larry
Are you placing the test case on the bolt face already behind the extractor and then closing the bolt stripped of firing pin and ejector plunger, and without the test case first having to fight its way past the extractor?
What I am saying is after firing a case with too much head space doesn't the case shoulder get blown forward to eliminate excess head space (fire forming). It shouldn't damage the case unless the head space is way to much. Isn't this what happens every time you fire a factory load round. The shoulder gets moved forward until it is a good fit to the chamber shoulder. Don't understand all the problems people have on this website with ammo. I have been reloading for accurate varmint riffles for 45 years without a single problem.
No I have seen a couple of gun that had the fireing pin bushed from too much head space. Ar it is very common . I have seen may with the primer pushed backward after shooting from wrong head space .
Get you the PO ackley books good read .
Larry
The Hornady Lock-N-Load Headspace Gauge 5 Bushing Set with Comparator can be a useful tool but it has a few drawbacks or caveats which were mentioned. Using an actual Headspace Gauge for .308 Winchester which should read 1.630" here is what we get.
First we assemble and zero the gauge as seen below:
Next I will measure an actual headspace gauge with a known 1.630" dimension:
At 1.624" the gauge is reading 0.006" low for a known gauge, These gauges do not provide an actual numeric value which is headspace, the gauge serves as a comparator. I can use it to measure a fired case and let's say I read 1.627 so I can adjust my dies down and size the case looking for a 1.625" dimension which tells me I set te case back 0.002" for the chamber I fired it in. The only way to know what you really have is to measure a known accurate head space gauge and get a good reference number.
Now if you want to accurately measure a chamber headspace you can use a headspace gauge. While they are popular in sets of Go, NoGo and Field dimensions there are more elaborate sets as this one shown below. The set is a .308 Winchester set.
The basic set is 8 gauges starting with a 1.630 Go and working up in 0.001 increments to 1.638 Field. Another trick I have used is getting some quality stainless steel shim stock and paper punching small gircles out. A small dab of grease and they stick on the base of the actual gauges adding to them. You can accurately get your chamber headspace accurately down to 0.001".
Now if you want to fire a case and say that case dimension is really close to my chamber then I like using the RCBS Precision Mic sets.
I can also check my RCBS gauges against a known headspace gauge.
Rather than tape I just prefer some known good shim stock.
Just My Take....
Ron
First we assemble and zero the gauge as seen below:
Next I will measure an actual headspace gauge with a known 1.630" dimension:
At 1.624" the gauge is reading 0.006" low for a known gauge, These gauges do not provide an actual numeric value which is headspace, the gauge serves as a comparator. I can use it to measure a fired case and let's say I read 1.627 so I can adjust my dies down and size the case looking for a 1.625" dimension which tells me I set te case back 0.002" for the chamber I fired it in. The only way to know what you really have is to measure a known accurate head space gauge and get a good reference number.
Now if you want to accurately measure a chamber headspace you can use a headspace gauge. While they are popular in sets of Go, NoGo and Field dimensions there are more elaborate sets as this one shown below. The set is a .308 Winchester set.
The basic set is 8 gauges starting with a 1.630 Go and working up in 0.001 increments to 1.638 Field. Another trick I have used is getting some quality stainless steel shim stock and paper punching small gircles out. A small dab of grease and they stick on the base of the actual gauges adding to them. You can accurately get your chamber headspace accurately down to 0.001".
Now if you want to fire a case and say that case dimension is really close to my chamber then I like using the RCBS Precision Mic sets.
I can also check my RCBS gauges against a known headspace gauge.
Rather than tape I just prefer some known good shim stock.
Just My Take....
Ron
That is a good post. I am not sure how you offset the zero on those digitals except by using a .006 feeler gage.
Dial calipers are easy to zero by just turning the dial to read 1.630 while checking the headspace gage.
Once the calipers are set it is a superior tool than that gage set since it can read lengths both shorter and longer than the gages and the gage cannot measure a case alone.
Dial calipers are easy to zero by just turning the dial to read 1.630 while checking the headspace gage.
Once the calipers are set it is a superior tool than that gage set since it can read lengths both shorter and longer than the gages and the gage cannot measure a case alone.
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