Lets talk headspace again!

[Palmetto-Pride]

Guys I am sure this has probably been talked about before, but I want to beat this horse just a little more. So I have a pretty good grasp of what headspace is and the importance of not having to much, but I wanted to talk about having tighter head space in relation to accuracy. My question is pretty much this. Is it better to have as little headspace as possible and still be able to chamber a round? Does having as little as possible lend its self to better accuracy?

[Brian Pfleuger]

It is generally true that less headspace is better for accuracy.

On a bolt gun, sizing fired cases for no more than 0.002-0.003 clearance is usually best. I recall a bit more, like 0.005 on a semi but I don't pay much attention to them so someone else should clarify if that's wrong.

On my .243AI Savage 11, I installed the barrel to have 0.002 more headspace than my dies adjusted all the way down size the cases. Makes adjustments easy.

[mete]

If each round chambers the same because of minimum headspace and minmum chamber dimensions that will be more accurate.

[Palmetto-Pride]

I am in the middle of a 6.5CM Rem/Age build I have GO and NOGO gauges I know how to use them. I put the GO gauge in and threaded the barrel until I just felt it make contact then I put the NOGO gauge in and the bolt wouldn't close. So at that point I know I am safe and within spec, then I put in a factory cartridge and I could get just a little bit more, I put the GO gauge back in and it will still close, but now I can feel come up on the gauge a great deal more. My thought was having the headspace a little tighter should and would lend itself to more accuracy. I have read that you shouldn't use a round as a GO gauge, but if you shoot or reload the same ammo all the time. WHY NOT? It seems like it would be beneficial to have it as close to the round you are shooting. As long as the bolt won't close on a NOGO gauge correct? Am I wrong it my thinking?

[Brian Pfleuger]

See, the thing is, Go and No Go gauges are based on SAAMI voluntary standards. There's no requirement that you follow them.

If you wanted, you could chamber your gun to the "No Go" gauge and then use one of the various fireforming methods to make the brass fit the chamber and then size it back 0.002 short of THAT dimension. That would give you more powder space and (perhaps) depending on how adventurous you are, a bit more velocity if you're willing to exceed published data.

Ultimately, it all depends on how comfortable you are going off on your own. If you're not, then you should follow SAAMI standards and follow published load data. If you are more adventurous, chamber the gun however you see fit. That's what I did.

The "how close is the brass to my chamber" is only valid for the first firing and for factory loads. You shouldn't chamber to factory loads because there's a tolerance in the SAAMI spec. One brand might fit, the next will be it's own "No Go" gauge.

[F. Guffey]

I wanted to talk about having tighter head space in relation to accuracy.

Is it better to have as little headspace as possible and still be able to chamber a round?

I wanted to talk about having tighter head space in relation to accuracy. My question is pretty much this. Is it better to have as little headspace as possible and still be able to chamber a round? Does having as little as possible lend its self to better accuracy?

Instead of tightening the head space lets talk about increasing or decreasing clearance. I use the length of the case from the shoulder to the case head to off set the length of the chamber. My cases do not have head space.

Then you go to having as little head space as possible; head space if fixed, a reloader is not increasing or decreasing head space. The reloader controls clearance. After firing a case the reloader has his first option; the reloader can neck size the case, when it comes to fitting the chamber with the case it does not get better than neck sizing.

When it comes to neck sizing reloaders can find many reasons for it not improving accuracy and they have trouble explaining head space, clearance and accuracy.

Does having as little (head space) as possible lend its self to better accuracy?

Again, I measure the length of the chamber from the shoulder to the bolt face. Meaning: head space is fixed, I do not increase head space, I do not decrease head space and for me it so simple because my cases do not have head space and all the gages I use to measure the length of the case from the shoulder of the case to the case head are comparators or case gages.


I have a 30/06 chamber that is .002" longer than a field reject length gage; that is .016" longer than a minimum length/full length sized case. When I fire cases in that chamber I add .014" to the length of the case from the shoulder to the case head. When I fire cases in that chamber I have the 'magic' .002" clearance.

F. Guffey

[F. Guffey]

I have read that you shouldn't use a round as a GO gauge,

I have read and heard that also and then I talked to this lady that attended finishing school.

F. Guffey

[FrankenMauser]

The "how close is the brass to my chamber" is only valid for the first firing and for factory loads. You shouldn't chamber to factory loads because there's a tolerance in the SAAMI spec. One brand might fit, the next will be it's own "No Go" gauge.

My 6mm wildcat is based on this very principle. ...And the fact that some companies still 'draw outside the lines'.

Remington factory ammo that I have measured has all been substantially under SAAMI minimum dimensions for .243 Win.

When my barrel was chambered, it was chambered with a minimum-spec .243 Win reamer so that Remington ammo would just chamber without binding. A "GO" gauge will stop the bolt, hard, and not allow the bolt to go fully into battery.

So, that rifle is intended for handloads built around the sub-SAAMI dimensions, but I can fire Remington factory ammo in a pinch (or if I want to retest something with my 'baseline' ... which also happens to be Remington factory ammo).
Handloads show zero to 0.001" expansion in the body after firing, except in the SAAMI-spec neck. Remington factory ammo, on the other hand, will show two to three thousandths expansion at the same locations (still far below measured expansion in factory .243 chambers).

But this rifle was a special case. And, even knowing the score... it still gives me trouble sometimes.

For the average rifle, I'd rather have headspace a little longer than minimum. It gives me room to size my brass back into spec with standard sizing dies if it 'grows' a bit too much with repeated use. But with chambers that are super-tight or on the short side, one is generally looking at custom dies or modifying standard dies, in order to get the cases back into tolerance for that chamber.

[F. Guffey]

For the average rifle, I'd rather have headspace a little longer than minimum. It gives me room to size my brass back into spec with standard sizing dies if it 'grows' a bit too much with repeated use. But with chambers that are super-tight or on the short side, one is generally looking at custom dies or modifying standard dies, in order to get the cases back into tolerance for that chamber

.

I form cases for short chambers; I form short cases before I start to cut a chamber. I can do all of that with a standard press, shell holder and dies; again my favorite shell holders is the one that only fits where it touches, something like a hand-me-down shirt. The 'looses' shell holder I have found is the RCBS shell holder, it has the most utility. I have shell holders that FIT, they fit for a different reason; when I fire a case with a heavy load it is not likely the case will fit the tight shell holders without driving them into the shell holder with a case friendly hammer, but with the RCBS shell holder I can really hammer the case head and still fit the case into the shell holder. I like that in a shell holder, I do not like hammering my case heads with heavy loads

Back to short cases; I form cases that are .011" shorter than a minimum length/full length sized factor, over the counter new ammo that, that is .016" shorter than a go-gage length chamber. Experimenters: When full length sizing a case with a standard die in the perfect world the case is sized .005" shorter than a go-gage length chamber of we are talking about a 30/06 case.

Then I have to explain short cases; short cases for short chambers means the chamber are short from the shoulder to the bolt face and the case is short from the shoulder to the case head.

For anyone trying to determine the difference between the length of the case from the shoulder to the case head and the chamber from the shoulder to the bolt face 'READ' to determine the number of responses that claim it can not be done or beyond the mere ability of a reloader. I would first suggest you scratch out all the responses that paint SAAMI with a wide brush claiming the answers are allusive and vague. And learn to zero a gage, learn to transfer and learn to use standards.

F. Guffey

[Gunplummer]

Lets not. The horse's ribs are showing.

[F. Guffey]

Is it better to have as little headspace as possible and still be able to chamber a round? Does having as little as possible lend its self to better accuracy?

there has to be something about sizing a case the reloader does not understand. All of my presses and dies have threads, threads allow me to adjust the length of the case from the shoulder to the case head when sizing. I can sized a case with no clearance between the shoulder of the case and shoulder of the chamber. I can size a case to minimum length and get .005" clearance when sizing cases for a go-gage length chamber. And then there is my military chamber with a field reject length chamber + .002" meaning the chamber is .016" longer than a minimum length/full length sized case. Because of threads on my dies and presses I can off set the length of the chamber with the length of the case, when sizing cases for that chamber I adjust the die off the shell holder .014".

F. Guffey