quote:

Originally posted by F. Guffey:

quote:

If sized to headspace on the shoulder these Norma cases gave good case life.

If sized to seat on the shoulder the case body ahead of the belt will not will not have case body support ahead of the belt.

F. Guffey

By the time maximum pressure is reached, the shoulder of the case will make contact with the shoulder of the chamber
and the head of the case will be in contact with the bolt/breech block/whatever and will have pushed it as far back as the locking surfaces will allow it to go.

If the chamber is cut so badly that there is not sufficient support ahead of the belt, the case will blow no matter how short you sized the case. In fact, if you sized the case too short I contend that it will be even more likely to blow the case out...

quote:

Originally posted by F. Guffey:
If sized to seat on the shoulder the case body ahead of the belt will not will not have case body support ahead of the belt.
F. Guffey

That is among the least informed comments I've seen recently on this forum.

quote:

Originally posted by F. Guffey:

quote:

If sized to headspace on the shoulder these Norma cases gave good case life.

If sized to seat on the shoulder the case body ahead of the belt will not will not have case body support ahead of the belt.

F. Guffey

Not the dumbest statement I've seen but right up there, fighting for the honor. It's like you are advocating in favor of excess head clearance. Just a silly thing to say.
To address the original post: Measuring the solid head was a common technique back in the days before everyone could afford a chronograph. Generally speaking, the experimenter was looking for the point at which the brass case had exceeded it's elastic limit. Obviously, if the solid head was expanding, the primer pocket was going to loosen.
One thing that has to be said is that you cannot determine what the pressure level might be by measuring the solid head. However, you can damn sure tell when you are too hot! If there is any measurable expansion of the solid head, the pressure is too high for that rifle with that brass. In order for the measurement to be valid, it has to be taken on once fired, neck sized brass. With new brass, it is possible you would be measuring distortion of the solid head, stemming from the expansion of the brass ahead of the web.
Brass from different manufacturers and brass from different lots will often start toexpand at different levels. Back in the day, it was generally accepted that Winchester brass was tougher than the others. If one went by case head expansion, this did seem to be the case. Norma brass was (and is) soft, so is Federal. Remington was softer than Winchester but harder than Norma.
In most rifles which are chambered for rimless cartridges, the cartridge protrudes by .110" to .155", depending on the desin parameters of the particular action. Single shot actions (like the Ruger #1)enclose most of the case head, apart form the extractor cut.
If the chamber is close to case diameter, with very little clearance, case head expansion is less apparent and it takes much more pressure to permanently deform the case head. Rimmed cartridges, because they are more fully enclosed, also seem to take more pressure before the head expands. This is probably why the 219 Donaldson Wasp could achieve such high velocities.
I one is using a load which loosens primer pockets after three or four firings, I can about guarantee he would be able to measure some case head expansion. The load is too hot.
I've used the case head expansion measurement when comparing standard cartridge performance to the AI derivative of the same cartridge. If I worked up to where the case head expanded by .001 then backed off to where it was zero. I felt I had established the practical max for that particular brass. Doing the same thing in the AI chamber, using brass from the same box, gave me a reasonably valid comparison. The pressure was roughly the same in both cases. By the way, if you do this, a 257 Roberts and a 257 Roberts AI don't perform much differently.
Rocky Gibbs always touted good case life with repeated reloading as the criteria for a safe maximum load, and he loaded to the limit of the brass. Consequently, his top loads were loads which were OK with the particular lot of brass he worked that load up in, but were not OK if a softer brass was used. Many of his customers did not heed this caveat and risked damaging their rifles and themselves as a result (some of them were just stupid!).
Today, the affordable chronograph provides a good means to confirm whether or not a load is safe. If the velocity is 100 fps over what pressure tested ammo produces, the pressure is also probably over that of the controlled sample. Regards, Bill

quote:

Not the dumbest statement I've seen but right up there, fighting for the honor. It's like you are advocating in favor of excess head clearance. Just a silly thing to say.
To address the original post:

I started by saying "If I had the luxury of disagreeing, I would disagree" I did not say, in my opinion it is a bad habit to head space a belted cases off of the shoulder, why?

"Not the dumbest statement I've seen but right up there, fighting for the honor. It's like you are advocating in favor of excess head clearance. Just a silly thing to say"

I assume no one on this forum has ever measured the clearance ahead of the belt, I assume no one on this forum has ever measured the clearance between the shoulder of the case and shoulder of the chamber. The reloader from New Zealand suggested head spacing the case off of the shoulder of the chamber. I do not agree. (Again) because the case body ahead of thge belt does not have case body support because the case is heads pacing off the shoulder of the case.

Silly thing to do? I believe reloaders that purchase Larry Willis Digital Head space gages are silly. Long before Larry all tool manufactures sold dial indicator stands, I have tool catalogs that goes back to 1900 that list dial indicator stands. And then there is the Larry Willis collet for sizing belted cases ahead of the belt. I have three sets of collets. I have found beltd cases that have expanded .011" ahead of the belt, if the case was supported ahead of the belt there would not be case body expansion ahead of the belt.

A smith was building bench rest type rifles, I was not involved until he found the chamber he choose required some very expensive cases, it was about that time he included me. He does not like the case lube I use so he insisted I leave my no-name lube at home. He also wanted me to bring 'the other #4 RCBS shell holder; I asked him how many cases he had to form, he had 480 cases boxed in groups of 20. He never measured the diameter of a case head in his life; any how, he wanted to know what 'that little hammer was for'.

F. Guffey

quote:

Rocky Gibbs always touted good case life with repeated reloading as the criteria for a safe maximum load, and he loaded to the limit of the brass. Consequently, his top loads were loads which were OK with the particular lot of brass he worked that load up in, but were not OK if a softer brass was used. Many of his customers did not heed this caveat and risked damaging their rifles and themselves as a result (some of them were just stupid!).

I purchased a barrel from a Ft. Worth custom shop, it started life as a 30/06 FN barrel. It was not marked so I measured the chamber and then posted the measurements on the Internet. A smith (Seaweed) in Arizona did the research and then said it was not a 30 Gibbs, 30/06 Ackley Improved but close. I used the one barrel to test 4 receivers. It worked but most thought my fire forming load was going to be to risky. I called Hogdon they said the load was not too hot for forming but after firing the load would be at the jagged edge of the maximum load.,

F. Guffey

quote:

Originally posted by F. Guffey:

I purchased a barrel from a Ft. Worth custom shop, it started life as a 30/06 FN barrel. It was not marked so I measured the chamber and then posted the measurements on the Internet. A smith (Seaweed) in Arizona did the research and then said it was not a 30 Gibbs, 30/06 Ackley Improved but close. I used the one barrel to test 4 receivers. It worked but most thought my fire forming load was going to be to risky. I called Hogdon they said the load was not too hot for forming but after firing the load would be at the jagged edge of the maximum load.,

F. Guffey

Now that's a dandy! The load is suddenly "hotter" when the brass fits the chamber than if the brass is smaller than the chamber. Sounds like George Santos teaching a physics class.

Speaking only for myself here. I have never understood the desire to load ammunition to maximum achievable safe pressure. Makes no sense to me. I never use maximum loads. I just get a rifle chambered for a more powerful round.

Or if you simply must have the absolute maximum for caliber, then you should buy a strain gauge. They are pretty affordable nowadays.

quote:

Originally posted by F. Guffey:

quote:

If sized to headspace on the shoulder these Norma cases gave good case life.

If sized to seat on the shoulder the case body ahead of the belt will not will not have case body support ahead of the belt.

F. Guffey

We are only talking of a few thou here not half an inch. There is still solid web ahead of the belt and this web is still well inside the chamber. Incipient case head separation if it occurs does so somewhat ahead of the solid web of a case not at the junction .
Everyone knows that manufacturers of the belted cases are pretty generous with their belt dimensions and loaded ammo pretty much rattles around in the chamber (slightly exaggerated). By minimal/partial resizing of a fired case it is possible to have a slight snug feel when closing the bolt on reloaded cartridges. This gives better case life than just FL resizing and shoving the shoulder back each time to get that factory rattle when headspacing off the belt.

quote:

Originally posted by Michael Robinson:
Speaking only for myself here. I have never understood the desire to load ammunition to maximum achievable safe pressure. Makes no sense to me. I never use maximum loads. I just get a rifle chambered for a more powerful round.

Or if you simply must have the absolute maximum for caliber, then you should buy a strain gauge. They are pretty affordable nowadays.

This is all well and good but this is not the way early experimenters thought, nor is the way modern day wildcat designers think; they wanted and want to squeeze every last bit out of the rifle and components. Is this wise or prudent? It is not. The question though, was regarding the efficacy of using case head expansion as a pressure indicator. As I said before, case head expansion cannot tell you what the pressure is but it can absolutely tell you when it is too high. The early Speer manuals contain data which was created this way and some of those loads are too hot for most brass. Bob Hagel loaded this way too and some of his loads were not for the timid! Regards, Bill

I agree, yet, the consensus here is that case head expansion is useless as a measure of chamber pressure.

To me, that is 100% correct, and besides that, old news.

My point is that we have reliable means now of testing pressure if needed.

I have never needed it and will never need it because I don’t push the pressure envelope in any caliber.

But reliable means of testing are out there for those who do.

The 21st century is pretty cool in that way.

Thank you all, once again. I will try to incorporate your opinions in future evaluations, looking especially hard at primers and any marks on the case head.

Headspacing belted magnums on the shoulder makes sense to me. In addition to Eagle's point, if this does leave a danger from lack of support ahead of the belt, then there's a dangerously large space in the chamber for the belt, which is supposedly the default headspace determinant in magnums. I say this because the fired cases from my Sako 338WM look as they were necked up from 308 Norma mag (if not 300 Win ) and I'm surprised I can't get more powder, rather than less, into them. So, if the belt is not governing headspace on new brass, what is?

The belt is establishing head clearance; it's just not doing a very good job of it. The nominal minimum headspace measurement for a standard belted case is .220". This coincides with the maximum cartridge HS measurement. The thing is, brass is never anywhere near maximum and a measurement of about .215 is pretty typical. Nonetheless, it is good practice to chamber to .220, for a serious hunting rifle. The last thing one needs is to get the one box of ammo with max dimensions, and have to try and get it into his .218 rifle. So, with .005" of head clearance built in, it is common and good practice to headspace on the shoulder after the first firing.
The same situation exists with rimmed cartridges. Nominal HS is .063 and brass is usually .058 or so. Again, one can headspace on the shoulder for subsequent firings, and improve case life. Regards, Bill

quote:

Originally posted by eagle27:

quote:

Originally posted by F. Guffey:

quote:

If sized to headspace on the shoulder these Norma cases gave good case life.

If sized to seat on the shoulder the case body ahead of the belt will not will not have case body support ahead of the belt.

F. Guffey

We are only talking of a few thou here not half an inch. There is still solid web ahead of the belt and this web is still well inside the chamber. Incipient case head separation if it occurs does so somewhat ahead of the solid web of a case not at the junction .
Everyone knows that manufacturers of the belted cases are pretty generous with their belt dimensions and loaded ammo pretty much rattles around in the chamber (slightly exaggerated). By minimal/partial resizing of a fired case it is possible to have a slight snug feel when closing the bolt on reloaded cartridges. This gives better case life than just FL resizing and shoving the shoulder back each time to get that factory rattle when headspacing off the belt.

Sounds great, again, a smith asked me to form 480 belted magnum cases to 8mm/338 Winchester mag cases, sounds simple enough but my dies would not fit the case body ahead of the belt. Meaning, long before you someone was sizing the case to seat on the shoulder or as they say they were sizing their cases with a fake shoulder. Anyhow, the case would not seat on the belt and on the shoulder at the same time. I have three lathes with two sets of collets. The smith was building wildcat rifles, he was eat up with everything he was being told on the Internet about forming cases. to get started he instructed me to bring the other #4 RCBS shell holder: that did not make senesce to anyone, I knew his shell holder would not fit some of the 480 cases. I told him I would bring a small ballpeen hammer, I also told him we could chuck up the cases and cut the extractor groove. I knew he was not going to measure the case heads before and again after firing so I furnished a box of micrometers. It took a while to get started, the next day he called for help. He had an A2 RCBS press, he had it locked up, he could not lower the ram because he had never adjusted a cam over press.

I ask him how he got the die that tight, and then he showed me the pipe he used on the handle.

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We are only talking of a few thou here not half an inch.

This was a time I measured clearance and If I was sizing on the belt I determined the difference in the length of the chamber from the shoulder to the bolt face. All other reloaders that ignored the expansion in front to the belt purchased a Larry Willis Digital Head space gage and a collet die to size the expanded case head IN front of the belt.

F. Guffey

That's an interesting story, FG, but a fraction weird and not something many reloaders are likely to encounter. It sounds as though the smith was trying to get what was virtually an industrial operation done on the cheap. He should really have given you virgin brass to work on.

Looking at 338WM drawings, I see that the brass just in front of the belt is rapidly becoming thinner and imagine this could become a problem of some sort if not supported by the chamber. However, I have not noticed any greater expansion there in my neck-sized 338WM brass. In fact, what I see is a taper expanding away from the belt, indicating the web is holding to an outer diameter smaller than the chamber ahead of that point.

quote:

Now that's a dandy! The load is suddenly "hotter" when the brass fits the chamber than if the brass is smaller than the chamber. Sounds like George Santos teaching a physics class.

Stonycreek, forgive, I can only guess I am typing too fast for you. I decided on the fireforming load, I thought it would be the perfect load, and then reloaders on the Internet got involved. Seaweed was kind, he suggested there is a possibility my fire forming load could be a little risky. I did not agree, I called Hodgdon.

HODGDON did not have a reason to show off and make themselves look good at my expense, they did want to know how I came up with that load. I explained to them I was going to fireform cases for a chamber that had a short neck so I formed a false shoulder. I used 4 receivers that were sold to me as being suspect. The cases formed perfectly to the chamber.

I used one barrel, one bolt and 4 receivers, it took time, if i did it again I would use 280 Remington cases because the 280 Remington case is longer than the 30/06 case from the end of the neck to the case head.

When fired and formed my cases lost .050" in length, a wild guestimate; had I used 280 Remington cases I believe I would have lost .030" in case length. And then there was the rational; Why did I believe the fireforming load was safe? TIME.

F. Guffey

SAmbarman,
All the tech is argueable, and up for grabs, lots of good info and some garbage of by gosh and by golley,,

Cutting through the chafe, load to book max, then cut back a grain or two and you will never have a problem I don't think, I never have..Most good factory guns are tested with a blue pill at 180,000 PsI or cup? I was told by a factory rep some years ago , go figure, but factory reps can be sho nuff bean counters..It is what it is!

Guffey is A goober. Take anything he posts with a huuuuuuuge dose of scepticism.