I disagree. Some reloaders full length size bottleneck cases such that their shoulder is set back .002" from its fired position. They don't care what the chamber headspace is from bolt face to chamber shoulder reference. The fired case headspace is close enough and typically .001" less than chamber headspace. And the resized round will have about .003" head clearance when put back in that chamber it came out of.
Checking headspace LR308 build
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Reloadron
Contributing Member
Bart, there is sometimes a small caveat with the RCBS Precision Mic sets. While the zero for a .308 Winchester (and other cartridges) should be 1.630" things do not always quite work out that way. My particular set is off slightly, not bad for .308 but not quite honest either. Here is what I did. I have a set of .308 Winchester headspace gauges. Matter of fact it is the set 1st Marine linked to in another thread but here they are:
The gauges run from 1.630" to 1.638" and the three odd gauges on the side are a 1.630" Go, 1.634" No/Go and a 1.638 Field gauge. They are all Forrester gauges. I know the gauges to be accurate as before I retired I dragged many of my gauges into the plant for testing. Anyway when placing the 1.630" Go gauge in my RCBS Precision Mic I read not quite a -0.001 or 1.6295". Granted this is not really bad but I have a set of .223 Remington gauges that are off by -0.002" and another .223 Remington set that is dead on balls accurate (I loved that movie) to use a technical term. While for most applications it isn't enough to matter other members have come up with wider margins of error.
Sorry about the glare but in this last image the headspace gauge is inserted in the RCBS Precision Mic and the slight error is sort of noticeable. Again, not a big deal especially considering how most use the gauge but none the less the gauge does not zero at 1.630".
Ron
For those that measure before and again after are using the gage as a comparator. For those that can verify it is a matter of keeping up with the error if they are going to compare measurements with SAAMI specifications. Like I have said before for most reloaders it is impossible to get every tool and chamber to agree. Life is simple when the object is to determine the difference in length between the chamber from the shoulder to the bolt face and the length of the case from the shoulder to the case head. The differences in length should be clearance.
F. Guffey
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Ron,
My 308 Win RCBS Mic reads -.001 on my Forster 308 GO gauge. My 300 Win Mag Mic reads +.001" from SAAMI spec for chamber shoulder .420" reference diameter distance from bolt face. Those tools have up to .001" error according to the RCBS rep I discussed them with. They're not meant to be exact; just compare case headspace at the shoulder from fired to resized position. They're very precise doing that.
My 308 Win RCBS Mic reads -.001 on my Forster 308 GO gauge. My 300 Win Mag Mic reads +.001" from SAAMI spec for chamber shoulder .420" reference diameter distance from bolt face. Those tools have up to .001" error according to the RCBS rep I discussed them with. They're not meant to be exact; just compare case headspace at the shoulder from fired to resized position. They're very precise doing that.
Read post #48.
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1stmarine
Member
@Reloadron,
I found the PTG and forster gauges to be dead on up to 1/2 thou. because that is the best I can do and I don't need more precision.
The question is, isn't the RCBS mic design prone to misreadings or being off because of the threads or bushing?
In any case, it is a pretty common practice to headspace using the loads we are going to shoot, many times Federal gold medal or Lapua.
When reloading, the shooter's goal is to replicate the factory loads both in terms of dimensions, speed and accuracy.
People tune up their reloads so we end up with consistency whether one uses custom loads or factory ammo in those places that might not allow reloads.
I follow the same precise brick and mortar directives. Some BR rifles might require a chamber for a unique reload and bullet.
I sill don't get why would anyone return gauges of different brands and measures. A go gauge of 2.631 is not because it is a mistake but because they
choose to stay with a larger lower limit as per SAAMI to make sure any kind of ammo would chamber. Actually in the case of the 308w 2.631 or 2.632 is
just about right for a good chamber.
Different gauges or entire sets are used by master gunsmiths all over the world including the ones who make match winning rifles.
This is a fact whether we agree about other methods or not.
I think we all agree the end goal is to have two parts to come perfectly together with minimum tolerances.
Perhaps others who chamber match grade chambers and rifles want to chime in.
I found the PTG and forster gauges to be dead on up to 1/2 thou. because that is the best I can do and I don't need more precision.
The question is, isn't the RCBS mic design prone to misreadings or being off because of the threads or bushing?
In any case, it is a pretty common practice to headspace using the loads we are going to shoot, many times Federal gold medal or Lapua.
When reloading, the shooter's goal is to replicate the factory loads both in terms of dimensions, speed and accuracy.
People tune up their reloads so we end up with consistency whether one uses custom loads or factory ammo in those places that might not allow reloads.
I follow the same precise brick and mortar directives. Some BR rifles might require a chamber for a unique reload and bullet.
I sill don't get why would anyone return gauges of different brands and measures. A go gauge of 2.631 is not because it is a mistake but because they
choose to stay with a larger lower limit as per SAAMI to make sure any kind of ammo would chamber. Actually in the case of the 308w 2.631 or 2.632 is
just about right for a good chamber.
Different gauges or entire sets are used by master gunsmiths all over the world including the ones who make match winning rifles.
This is a fact whether we agree about other methods or not.
I think we all agree the end goal is to have two parts to come perfectly together with minimum tolerances.
Perhaps others who chamber match grade chambers and rifles want to chime in.
And I wonder; why doesn't the master gunsmith make his gages? In the mid '50s a smith discussed the choice, he mentioned smiths that did make their gages, he said he chose to purchase gages and then went on to cover another method/technique. The problem with the go-gage when checking the chamber; we all know the bolt will just close on a go-gage, and then there is that problem with 'by how much?'.
F. Guffey
Reloadron
Contributing Member
Bart, I agree without a doubt. The gauge does what is expected of it and thanks by the way as I was not sure RCBS had a tolerance they liked to work within. My guess is the average shooter will measure a fired case, get a number and bump his case back a few thousandths (or whatever) be happy and life goes on. Incidentally, as you mentioned the gauges, in my experience are very linear. I can run all eight gauges through the RCBS Mic and measure the 0.001' graduations. Good stuff and mine run back at least 25 years or so when they did cost less.
Then too, the buck bought more 25 years ago.Ron
As does the Hornady LNL and my nylon bushing gauge used with calipers.
This whole case headspace thing may well be one of the first things a reloader using full length sizing dies should learn then master. If they measure case headspace on their neck only resized cases, they can see them grow in headspace a few ten-thousandths every cycle. When one chambers with the slightest bolt resistance, that case headspace is virtually equal to chamber headspace at its shoulder.
Reloadron
Contributing Member
Yeah, I have to agree with that strongly. I did a thread some time back on case gauges and brought up the Hornady as well as RCBS. They are tools and like most tools only as good as those using them. Anyway, I don't want to drag this thread off topic.
Ron
And I can remember forum members referring to the tools as head space gages.
F. Guffey
Reloadron
Contributing Member
In all fairness, especially to the new hand loaders and reloaders, it becomes easy to call a case gauge a headspace gauge. A simple Google of "cartridge headspace gauges" reveals some interesting images. Matter of fact I see more case gauges than what are actually headspace gauges. After several forum discussions on this subject the general consensus was if many guys making case gauges want to reflect "cartridge headspace gauge" then so be it. A good example would be HORNADY - LOCK-N-LOAD™ HEADSPACE GAUGE TOOL where Hornady, who makes the tool calls it a Headspace Gauge Tool. We can drag the discussion back to the SAAMI cartridge drawings and point out how the cartridge drawings do not reflect a headspace dimension and only the chambers do but... it just becomes a moot point. As long as the reloader knows how to use the tool and how to interpret the data it provides I doubt it matters much. We just end up with a game of words or semantics and nobody comes away with anything of any value learned.
Just My Take....
Ron
I do not agree, when members were trying to reinvent the definition of terms I was saying the Sinclair/Hornady gage was not a head space gage because of the radius, that was when I suggested if the gage was going to be used it should be verified and adjusted for error. I also suggested it could be used as a comparator but their tool did not get top billing on Google. The Digital comparator got top billing when it was referred to as the digital head space gage. Again, L.E. WILSON has been selling and making the Wilson case gage for close to 65 years. Most reloaders have referred to the Wilson case gage as a drop in gage. I read the instructions, selected a straight edge and added the feeler gage; because the Wilson case gage is a datum based tool it's ability is limited only by the user.
F. Guffey
Reloadron
Contributing Member
We have had this discussion about a dozen times. You are free to totally disagree and based on past discussion I am well aware you disagree. I also know several times over your comments on the Wilson gauge and straight edge. I am the guy shoving actual headspace gauges in my other tools to verify them. You are preaching to the choir. I can't change Hornady's claims of:
Ron
Should we contact Hornady with the error of their ways? They refer to "headspace of the cartridge" but if cartridges don't have headspace how is that possible? I will just assume if Hornady and their friends say it is so then it must be so. The Wilson gauge as it stands alone is at best a Go/NoGo gauge, that is all it is. The case either does or does not conform to the gauge limits. That is as good as it gets. Now if you wish to share with the class how the Wilson case gauge can be used with a straight edge and feeler gauge to get some actual numbers then have at it but mere mention of straight edge and feeler gauge tells the new hand loader nothing and leaves them hanging.
Ron
What about those thousands who still claim headspace is that place between the breech face and cartridge head when the round fires?
That was the original standard in the 19th century when all rifle cartridges were rimmed; both straight wall and bottleneck ones.
That was the original standard in the 19th century when all rifle cartridges were rimmed; both straight wall and bottleneck ones.
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Reloaders and smiths can be around something all their lives and know nothing about it. I said the Wilson case gage is a datum based tool. To most reloaders the datum is a line. And I said the datum in the Wilson case gage had a radius, if Horrnady was as clever as Wilson Hornady could have made their round hole with a radius work.
They also accused me of making too many mistakes so I went to visit them. I made it clear I asked about their tool before I purchased it and I made it clear before I purchased the tool I had 2,000 cases to work on. And then then their minds cleared up and said they had a contractor that had problems with case hardening. I then asked them where this contractor was located because it meant nothing to me to go by and visit them while I was there, it was about that time Hornady got busy and explained to me they had already changed contractors. After all of that I asked another question; it was clear he was making up the answer and had never performed the reloading task, he was repeating what he had heard, and I asked him if he had ever formed cases it the manner he was describing and his answer was 'NO!'.
And then there was this Schnauzer, I asked a lady in the northwest office who the Schnauzer belong to; she said the Schnauzer belonged to her and then she ask me why I wanted to know about the Schnauzer. I said I was hoping it belonged to the person that sat at the desk on the rear canter row. And she ask what difference that would make and I said your Schnauzer is eating the lunch of the person that sits at the center desk on the rear row. Anyhow, I got her autograph, she signed a copy of their parts catalog. She was a most pleasant person and wanted to make sure I was being helped. So I asked another question, it had to do with annealing and testing cases, it had nothing to do with being necessary. The question had to with deterring when is it necessary.
F. Guffey
1stmarine
Member
If this gives someone too much work and grief stick to muzzle loaders and airguns where the headspace is always dead on. lol
Reloadron
Contributing Member
Don't start Bart, don't even start!
What about the poor starving reloaders of... My head hurts, I am going to take a nap.Ron
Hormady could have made their gage as accurate as the Wilson case gage; problem, they do not know how. And then there is another maker of a comparator he calls a head space gage, he asked me to agree with him because the reloading industry would be better off. The comparator is a comparator, a case gage is a case gage. And then there are chamber gages, I make chamber gages, my chamber gages have case head protrusion. Other chamber gages are rip offs of the Wilson case gage.
F. Guffey
RogueNathan
Member
Hello THR team!
We're happy to help:
-Faxon does warranty that our barrels will fully function with .308 Winchester ammunition on a properly headspaced system. In fact, we published some bolt dimensions for what specifically we chamber the barrel for. http://faxonfirearms.com/blog/technical-interface-documents-faxon-barrels/
-All our barrels are headspaced, individually, with custom tool steel hardened gauges. We maintain these gauges under AS:9100 Q/C inspection and gauge control requirements.
RogueNathan
Member
We specifically use .308 Winchester "Production" reamers for maximum compatibility.
The issue is 7.62x51 foreign surplus can have issues in the neck/throat. Specifically on a minimum chamber depth, during firing its brass will spill into the freebore, causing extraction issues. This is VERY rare, but it happens and Faxon believes in publishing specs rather than deal with rare customer service issues.
If one even goes .002" back from SAAMI Gominimum before even the No-Go will rotate, the issue is non-existent.
.308 shooters tend to want really tight chambers for maximum accuracy (or sadly many shooters never check their headspace and .308 is the equivalent of the "wild west" for bolt manufacturing) and many then shoot the cheapest surplus they can find. Accomplished reloaders will not see an issue, at all.
1stmarine
Member
Hi Nathan,
Thanks for chiming in. I think giving the information of the bolts will help others and I think it is always a good idea to have the bolt matched
to the barrel and/or ordered from the same manufacturer like you do.
This way people can make sure the headspace is precisely as advertised.
I like the chambers on the tight side and leave NATO and surplus for other guns but commercial rifles
should be able to manage anything for versatility and to avoid problems.
Thanks for chiming in. I think giving the information of the bolts will help others and I think it is always a good idea to have the bolt matched
to the barrel and/or ordered from the same manufacturer like you do.
This way people can make sure the headspace is precisely as advertised.
I like the chambers on the tight side and leave NATO and surplus for other guns but commercial rifles
should be able to manage anything for versatility and to avoid problems.
"maximum compatibility" and then the issue. Checking the length of the chamber from the shoulder of the chamber to the bolt face after reaming, or after purchasing. I am the fan of knowing the length of the chamber before firing; when I check the length of the chamber from the shoulder to the bolt face I do not want to know if a go-gage will allow the bolt to close, I do not want to know if the bolt will close on a no go-gage, I want to know the length of the chamber in thousandths. I believe it is a measurement that is more than 'nice to know' information.
Reloadron, has a nice set of gages, when it comes to the spread his set is short on both ends because there are times I check short chambers and other time I check long chambers. Again, I want to know the length of the chamber from the shoulder of the chamber to the bolt face.
Reloaders have mastered the .002" bump and have a goal of 20+ firings. All I can do is off set the length of the chamber from the shoulder of the chamber to the bolt face with the length of the case from the shoulder of the case to the case head. So I ask; is measuring the length of the chamber in thousandths by a smith and or manufacturer possible?
F. Guffey
Again, I purchased a mill from a resource member of another forum, he was building a period correct 03 Rock Island for 1911. He had at least 20 head space gage for the 30/06 with a few that went back before SAAMI. It aggravated him to not know the length of the chamber, he knew the no go-gage would not allow the bolt to close and he knew the bolt would close on a go-gage but he did not know by how much. So without a gage I determined his chamber was .0025" longer than a go-gage and .0025" shorter than a no go-gage,
I know; that is good enough, but he wanted a go-gage length chamber. I explained to him every time he fired a minimum length/full length sized case the case would have .0075" clearance. He wanted to off set the length of the chamber with another bolt. He has no fewer than 100 Springfield bolts, I offered to check the effect each bolt had on off setting the length of the chamber; he knew I have no fewer than 03 replacement bolts. problem: I assured him collectively we did not have an 03 bolt that would off set the chamber by .0025" but I did not mind measuring them.
I offered to form/size cases to fit his chamber. He is the only reloader I know of that has a hydraulic reloading press. Problem, like all other presses his press will not move the shoulder forward meaning his cases were too short and he had no interest in offsetting the length of his chamber with cases like the ones I use that have been fired in trashy old chambers that were too long from the shoulder of the chamber to the bolt face..
And then I thought I wanted to go hydraulic, with his back ground he had enough parts and pieces to put one together. When I got home and unboxed the equipment I found all of the cylinders/pistons and valves were air operated. For me air would be too slow and then there was the bigger problem. The pistons and valves were operated with 2,000 PSI. Room was not the problem, I have room for bigger pistons that operate with less pressure,
F. Guffey
Yes, I think so. Anthing is possible with suitable shafting, gearing and camming .
Others may not think so.
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