I just finished building an annealer and got a chance to use it yesterday. After a conversation today about it's use actually helping the accuracy potential of a gun, I decided to undertake a test tonight.
I have a gun whose case is based on the 416 Rigby. It is shortened considerably. The 416's body is formed down to become the shoulder and neck of my case. About .800 is cut off. The hardness of that brass down at the body is greater than the neck of the parent case. I wanted to know how hard MY necks were as compared to the factory necks and if there was any difference in the 2, what could be done to replicate the factory results. Also, My theory on annealing necks seems to be considerably different than the opinions of 99% of people, so I thought I'd share what MY findings are on the subject.
For the most part, I have tried to make the test data/conditions consistant. For lack of forsight a year ago, I cannot use 100% consistant cases. An additional test some time in the future could complete the test with 100% accuracy, but, that's for later.
I have brand new cases that have never been fired. I have a couple of the pieces that were cut off the necks of the brand new cases. I cut up a piece of brass that has been fired at least 10 times, perhaps more. I have not kept track of the firings because I figures that these brass were scrap anyhow, in hindsight, they may work well. I have no use for # of firings so when they die, I will throw them out.
Now, in addition to those 2 cases I have a case from my old barrel that very closely resembles the new, It has been fired 45+ times (and was primed for another go). This also got cut up.
I started by taking the standard that comes with the tester and checking it. It Rockwelled at B72.5 the markings on it say it should be 73 +- 1.0 OK, Im happy with the tester.
I started with the neck that was cut off the new case, obviously never fired. (pulled out of the chip pan in the lathe) It rockwelled at 40.0 twice. The neck from my 10 times fired case that was just run through my annealer came up with readings of 35, 29.5, 30, 26, 30. Some of the error can be attributed to the shape of the part in the tester. Putting a potato chip on the anvil, getting it to sit flat and getting the penetrator to start properly is difficult. In any case, one could say My new necks are considerably softer than the factory ones.
The case neck from the 45 times fired case gave readings of 46.5, 44, 50, 45.5. Now, I cannot say for sure when the last time was that that piece of brass was annealed, but, when it DID get annealed, it spent a LOT more time in the torch than my new ones. It is a good case for work hardening being a reality. This piece of brass was also from a different lot than the others tested and as I pointed out above, sorry I didn't get them all from the same lot. I would make an educated guess that this brass is VERY similar to the brass I have now, but, that's just a guess.
Also, keep in mind that as I was testting, I would move the part so as to show the range as I went around the neck. I can only get readings about every .100 anyhow, since the metal is distorted after testing. In general, throughout the entire time, readings seemed to repeat in certain areas of the brass leading me to beleive that change is not only from my part being shaped in such a way as to be difficult to test, but also from very real changes in hardness. What the changes relate to, I cannot say at this time. I would guess, thickness of the brass being inconsistant, and causing changes in temperature when in front of a torch is a good place to start.
The body's of the cases were as you would guess, much harder.
The unfired body
On to the bodys. Now these are a lot easier to get in the tester and get good readings off of. First, they're a lot bigger, so there's more to test.
The Unfired case, measured 84, 84, then a different piece from the other side of the case measured 86, 86. Ok, I'll buy that its about 85.
The 10 times fired case, measured 88, 87, 78 (possible a bad reading because of the set) 84, 85. Not much change if any. Pretty interesting. I would have thought that it would also work harden much like a piece of steel that got forged. Increase in density and decrease in volume. Not apparently so. Not at least in any great amount.
The 45 times fired brass, admitedly, from another lot, measured 87, 87, 87, 87. Well, about 87.
Now, I don't know how hard brass gets on the B scale. Marine stuff is MUCH harder than the softy crap we deal with.
If I had to make a conclusion, I would say that through time, pretty darn little changes. Now, this is not a test of how mallable the material is, simply it's hardness. Perhaps some crazed metalurgist out here can add something that would be heplful or continue the testing.
My current annealing process is done with a dual motor, microprocessor controled gizmo. A stepper motor moves another spin motor into a flame , spins the case and removes it after a period of time. I DO NOT quench the cases and the case spends LESS THAN 2 seconds in the flame. I'm not sure exactly ho long it is, if someone want's to know to the 1000th of a second, I can check the program in the simulator but suffice to say , the case gets NO WHERE NEAR red hot. And, it goes from roughly 85 rockwell, to 35. I take these cases out of the annealer with my fingers immediately after being torched and put the next one in. The total process takes less than 5 seconds. My skin on my 2 fingertips did get a little hard, but never burnt. That was after doing 30 cases. No big deal. I just grabbed down as near the base as I could. After the annealing process, there is absolutely no discoloration of the brass whatsoever. The only thing that can be seen is where fingerprints were not properly wiped off the case before heating it. They show up and need removed with some nevr-dull. Otherwise, they come out as pretty as they went in.
Determining if this means anything is left up to the reader
I have a gun whose case is based on the 416 Rigby. It is shortened considerably. The 416's body is formed down to become the shoulder and neck of my case. About .800 is cut off. The hardness of that brass down at the body is greater than the neck of the parent case. I wanted to know how hard MY necks were as compared to the factory necks and if there was any difference in the 2, what could be done to replicate the factory results. Also, My theory on annealing necks seems to be considerably different than the opinions of 99% of people, so I thought I'd share what MY findings are on the subject.
For the most part, I have tried to make the test data/conditions consistant. For lack of forsight a year ago, I cannot use 100% consistant cases. An additional test some time in the future could complete the test with 100% accuracy, but, that's for later.
I have brand new cases that have never been fired. I have a couple of the pieces that were cut off the necks of the brand new cases. I cut up a piece of brass that has been fired at least 10 times, perhaps more. I have not kept track of the firings because I figures that these brass were scrap anyhow, in hindsight, they may work well. I have no use for # of firings so when they die, I will throw them out.
Now, in addition to those 2 cases I have a case from my old barrel that very closely resembles the new, It has been fired 45+ times (and was primed for another go). This also got cut up.
I started by taking the standard that comes with the tester and checking it. It Rockwelled at B72.5 the markings on it say it should be 73 +- 1.0 OK, Im happy with the tester.
I started with the neck that was cut off the new case, obviously never fired. (pulled out of the chip pan in the lathe) It rockwelled at 40.0 twice. The neck from my 10 times fired case that was just run through my annealer came up with readings of 35, 29.5, 30, 26, 30. Some of the error can be attributed to the shape of the part in the tester. Putting a potato chip on the anvil, getting it to sit flat and getting the penetrator to start properly is difficult. In any case, one could say My new necks are considerably softer than the factory ones.
The case neck from the 45 times fired case gave readings of 46.5, 44, 50, 45.5. Now, I cannot say for sure when the last time was that that piece of brass was annealed, but, when it DID get annealed, it spent a LOT more time in the torch than my new ones. It is a good case for work hardening being a reality. This piece of brass was also from a different lot than the others tested and as I pointed out above, sorry I didn't get them all from the same lot. I would make an educated guess that this brass is VERY similar to the brass I have now, but, that's just a guess.
Also, keep in mind that as I was testting, I would move the part so as to show the range as I went around the neck. I can only get readings about every .100 anyhow, since the metal is distorted after testing. In general, throughout the entire time, readings seemed to repeat in certain areas of the brass leading me to beleive that change is not only from my part being shaped in such a way as to be difficult to test, but also from very real changes in hardness. What the changes relate to, I cannot say at this time. I would guess, thickness of the brass being inconsistant, and causing changes in temperature when in front of a torch is a good place to start.
The body's of the cases were as you would guess, much harder.
The unfired body
On to the bodys. Now these are a lot easier to get in the tester and get good readings off of. First, they're a lot bigger, so there's more to test.
The Unfired case, measured 84, 84, then a different piece from the other side of the case measured 86, 86. Ok, I'll buy that its about 85.
The 10 times fired case, measured 88, 87, 78 (possible a bad reading because of the set) 84, 85. Not much change if any. Pretty interesting. I would have thought that it would also work harden much like a piece of steel that got forged. Increase in density and decrease in volume. Not apparently so. Not at least in any great amount.
The 45 times fired brass, admitedly, from another lot, measured 87, 87, 87, 87. Well, about 87.
Now, I don't know how hard brass gets on the B scale. Marine stuff is MUCH harder than the softy crap we deal with.
If I had to make a conclusion, I would say that through time, pretty darn little changes. Now, this is not a test of how mallable the material is, simply it's hardness. Perhaps some crazed metalurgist out here can add something that would be heplful or continue the testing.
My current annealing process is done with a dual motor, microprocessor controled gizmo. A stepper motor moves another spin motor into a flame , spins the case and removes it after a period of time. I DO NOT quench the cases and the case spends LESS THAN 2 seconds in the flame. I'm not sure exactly ho long it is, if someone want's to know to the 1000th of a second, I can check the program in the simulator but suffice to say , the case gets NO WHERE NEAR red hot. And, it goes from roughly 85 rockwell, to 35. I take these cases out of the annealer with my fingers immediately after being torched and put the next one in. The total process takes less than 5 seconds. My skin on my 2 fingertips did get a little hard, but never burnt. That was after doing 30 cases. No big deal. I just grabbed down as near the base as I could. After the annealing process, there is absolutely no discoloration of the brass whatsoever. The only thing that can be seen is where fingerprints were not properly wiped off the case before heating it. They show up and need removed with some nevr-dull. Otherwise, they come out as pretty as they went in.
Determining if this means anything is left up to the reader
