I am used to using the ejector flow as a sign of pressure. What about a CRF action with the manual ejector?
Will I see brass flow into the slot as a pressure sign?
Will I see brass flow into the slot as a pressure sign?
Pressure signs
- Thread starter BigWyoming
- Start date
How much growth am I looking for - is any bad?
The ship has sailed.
I shot my factory ammo for break-in and forming. Now, I'm starting load development.
In the past, I looked for the circle of death on the head and backed away from it. Most nodes were found well below that, so no worries.
Planned on doing the same but didn't know if it would show different with the manual ejector slot vs the plunger.
RegionRat
Gold $$ Contributor
Case head growth depends on many variables, and sometimes the wrong combination of those variables can give you the wrong impression about your load's pressure. The above advise is still good, in that if you see brass flowing into features like the ejector slot the pressure is more than likely above the design limit. Even a small ejector slot is big enough to show the problem, but small ones mean you must watch close.
Cartridge brass properties are not identical between all manufacturers or brands, and can even vary within one facility making different cartridge designs. As a result, there is some variation in reading the tea leaves of brass flow from over-pressure. But, by the time you are seeing images of the label from the case on your bolt face, and seeing imprints of ejectors on the brass, most times it really is from over-pressure and should not be ignored.
There can be some examples where the primer cup beings to flow long before the other over-pressure symptoms arrive, and also instances where they happen at the same time and the primer cup doesn't warn you early enough.
I still recommend using a chronograph if at all possible, and tracking the expectations as you work up. Those expectations should be from multiple reliable sources when possible. Unless someone is prepared to gain the background to measure pressure, then play it safe on the days when you explore the higher ends of load recipes and don't ignore any of the warning signs. You may have some spare fingers, but you only have two eyes and I recommend keeping them both. YMMV.
Cartridge brass properties are not identical between all manufacturers or brands, and can even vary within one facility making different cartridge designs. As a result, there is some variation in reading the tea leaves of brass flow from over-pressure. But, by the time you are seeing images of the label from the case on your bolt face, and seeing imprints of ejectors on the brass, most times it really is from over-pressure and should not be ignored.
There can be some examples where the primer cup beings to flow long before the other over-pressure symptoms arrive, and also instances where they happen at the same time and the primer cup doesn't warn you early enough.
I still recommend using a chronograph if at all possible, and tracking the expectations as you work up. Those expectations should be from multiple reliable sources when possible. Unless someone is prepared to gain the background to measure pressure, then play it safe on the days when you explore the higher ends of load recipes and don't ignore any of the warning signs. You may have some spare fingers, but you only have two eyes and I recommend keeping them both. YMMV.
I had the same questions with the mechanical ejector on the Kelbly Atlas. I learned to watch velocity and primer cratering. @RegionRat nailed it. Flow is way hot.
It's been done to death. There are no pressure signs that work to stay within SAAMI limits. The standard fairly recent example is all the advanced hand loaders who published data on the Shooting Times Westerner based on pressure signs. That published data based on seeing pressure signs and backing off turned out to be almost invariably 10K over. There was a long and visible dispute between Bob Hagel and Ken Waters over the usefulness of case head measurement in their respective writings. Found in Pet Loads and in Bob Hagel's articles and books. Fun to read. The bottom line to repeat myself is that by the time pressure signs show up pressure is way too high by SAAMI standards. The only reliable indication is velocity of substantially the same components in very similar rifles.
I use velocity also - I suppose I should have mentioned that.
Primers have always been too subjective for me to read. Velocity and ejector marks were the stopping points.
To be clear, all loads are below that pressure tell. I have no desire to load near max in case something is different on a particular day that pushes me over. Using velocity nodes, I usually find one before I see what I deemed as pressure signs. But, I do want to know where pressure is so I can avoid loading next to it.
I know it's a dead horse and we all do it different. Thanks for all the information above!
Primers have always been too subjective for me to read. Velocity and ejector marks were the stopping points.
To be clear, all loads are below that pressure tell. I have no desire to load near max in case something is different on a particular day that pushes me over. Using velocity nodes, I usually find one before I see what I deemed as pressure signs. But, I do want to know where pressure is so I can avoid loading next to it.
I know it's a dead horse and we all do it different. Thanks for all the information above!
I will agree it's very hard to pick pressure from the ass end of a case look at the first picture I deliberately overloaded a couple of cases first one I stopped and rightfully so have a look.
Now if you know anything about a 260 Remington first load is warm , it was a great rifle shot unbelievably well out to1200 yards I would not recommend anybody use loads .
Trying to read pressure from a primer very hard to do the way I do it is if you can get 7 or 8 handloads out of a case before you need to bump a shoulder you have a good working load .
Now if you know anything about a 260 Remington first load is warm , it was a great rifle shot unbelievably well out to1200 yards I would not recommend anybody use loads .
Trying to read pressure from a primer very hard to do the way I do it is if you can get 7 or 8 handloads out of a case before you need to bump a shoulder you have a good working load .
Ackley quotes Vernon Speer as saying in 1956, when writing a load book, work up to brass change and then back off 6% powder charge.
I wanted to work up to long brass life. When I reloaded, I was looking for primer insertion being too easy. This threshold is inexact. That threshold could vary by more than a grain of powder. But if I measure the extractor groove all the way around with dial calipers before and after firing.... this threshold is repeatable down to a small fraction of a grain. The groove may bulge in one spot and have no effect on primer insertion, but it is a precursor.
I don't back off 6%. My variations in components and process are much smaller. My main concern is with temperature. I have not been characterizing temperature effects on powder, but using other's data.
I wanted to work up to long brass life. When I reloaded, I was looking for primer insertion being too easy. This threshold is inexact. That threshold could vary by more than a grain of powder. But if I measure the extractor groove all the way around with dial calipers before and after firing.... this threshold is repeatable down to a small fraction of a grain. The groove may bulge in one spot and have no effect on primer insertion, but it is a precursor.
I don't back off 6%. My variations in components and process are much smaller. My main concern is with temperature. I have not been characterizing temperature effects on powder, but using other's data.
Only if you use the same case which is what I do , my first firing for the day is the same case every time .
By its vary nature looking at primer or brass variations is testing to the limits of those components which should never fail at normal SAAMI.
Years ago a calculation was done by someone at Lawrence Labs at Berkeley to estimate the pressure that would be required for hard bolt lift. Conservatively that pressure was estimated to be around 70kpsi.
In reality, looking at conventional pressure signs ignores the only real data that we have for pressure which is the published load data. Short of instrumenting and calibrating our rifle velocity is the only way to link our actual data to compare to published test data and infer peak pressure from that information. In doing so it’s also important to account for barrel length. This is especially important when comparing data from 24” test barrels to 20” and shorter barrels.
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And the trail to the top of Mt Everest does not meet county code for staircase construction.
RegionRat
Gold $$ Contributor
Completely on point.
Not many of the things you encounter in an average life hit the kinds of pressures and stresses of a gun barrel or the brass. When we design a weapon system, the lawyers and politicians have a say in how much safety margin and reliability we are supposed to use in our designs and tests. Another different committee decided on ammo specs, some of them were DoD and some are commercial. If I were to tell you that the vast majority of the people involved were incompetent, you would wonder how the few who keep you alive can stand the debate.
Educate yourself and stay alive. If you don't want to spend the time to learn the issues, stay on the side of the safety margins and keep your fingers and eyes.
RegionRat
Gold $$ Contributor
I'll add GRT and to also consider learning to strain gage to this list.
RegionRat
Gold $$ Contributor
There can be two reasons for this.
A well behaved system is called so when the response to the change per step of powder charge is proportional and smooth. A poorly behaved system can become non-linear without warning.
In both instances, there is a statistical variation for each step. This is why your pressure margins should be on the order of a significant step back from the point where you observed damage.
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