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We got in a 5 digit Rock Island made 03. We aren't much into it since the stigma but was curious what the Rockwell on the receiver ring should be? Ours tested out to 52 Rockwell mid way on the top of the receiver ring. Where else should we test it to see if it's a safe rifle?
NO five digit RI is "safe" since it is considered a low number. The "safe" serial number is usually is usually considered to be above 285,000.
I understand, but I'm looking for technical information, info gathered from "safe action" Rockwell tests.
Pretty sure I'll get railed for trying to get info on a "unsafe" action but if a weapon falls within the safe specifications then why throw it out?
For what I know they changed the hardening process. Therefore it might not be something you can simply measure by the surface hardness. Or in other words: why risk something for an item which is known to be in an unsafe serial range?
It's not a matter of throwing something out, these don't give warning when they break. They don't crack or just fracture, they shatter like glass. They go to pieces all at once and there's a danger there. I'm not sure you can forecast which is in this possible group except by the serial range. I wouldn't chance it. Just because they've been used for decades doesn't mean it won't happen...safety first?
I'm sort of quoting off the study the Marines did of this in 1938. So honestly my knowledge is mostly only what I'm reading.
But the Marines report on the Rockwell hardness test states this. That both low and high number receivers were failing the rockwell test. If they were too soft, they were not as much of a risk as if they were too hard. If soft, the receivers could be used, but they would eventually stretch until finally the rifle lost headspace and would be unserviceable. If too hard, they were prone to shattering when you had a rupture. The hard receivers were the ones the Marines were concerned about. And they did have both Low and high number receivers that were too soft or too hard.
The Marines do state they have the ability to fix too hard receivers in what they called a "Drawback Process." They would heat the receiver to a certain temperature for a specified amount of time, that would draw the metal back the desired amount of points, and then they would let it air cool at room temperature. This brought back elasticity and toughness to the metal.
The Marines state the safe range for the rockwell hardness test is between 20 and 45 Rockwell "C" Hardness.
I hopet his helps you some in your search.
Very interesting Steve. It was my impression that over hard crystalized steel could not be reversed. Any data on the Marines actually using the drawback process, or did they just scrap receivers due to time and other constraints.
This has come up before, and you would think Springfield would have done it with their resources if possible. Also no new companies with modern facilities have done it either.
I'm sure there would be a market to bring low numbers up to shooting status!
I ask because as a machine shop, we have the equipment to heat treat and measure Rockwell. We're more interested in the possibility to rescue for testing, not resale
I guess you'll be able to tell us after...Quote:
Originally Posted by mwells72774
You know to be honest, I can't really remember where they went from there. You see hundreds if not thousands of pages on the low number recievers in the Marine files, but most of the time you just see them concluded that they shouldn't shoot rifle grenades with low numbers to be safe.Quote:
Originally Posted by pickax
Then in 1938, the Marines had a big push to try to fix receivers. Which they honestly had trouble with both lows and highs, which they called "Unders" and "Overs." That is when they started trying to fix the overs and unders with heat treament that were too soft and too hard. They claim in the study they could fix them. Hard receivers only went through the draw back process. The softs went through a heat treament with oil quench, and then a drawback process as well. But to be honest, I can't remember where it goes from there. I don't think they did it a long time if my memory serves me right. Now whether it just wasn't a success or the war was escalating and they were in a hurry and quit, I honeslty can't remember.
This was also about the time, they sent a rep to SA to learn how to do hatcher holes and enlarge the gas escape hole in the bolt. So they might have just screw heat treating the receives with heat treament and did hatchers as a much easier and quicker band aid fix.
If I get time early this week, I will dig those files out and see where it went. I just can't remember off the top fo my head. It's been a while since I looked at those and I've really didn't read that series of docs that close. I think it does explain why they quit doing it, but I can't really remember.
I do have the rockwell case study on hand though, because it explains some Marine traits on the rifles they rebuilt, so I have that filed where I know where it is is. But this is the process as they describe it on the doc for how they fixed hard/brittle receivers.
https://www.milsurps.com/images/impo...35620AMb-1.jpg
I read the case study of the heat treament a little more. In 1937 someone from the Philly Depot traveled to the Pennsgove Labrotories of the Dupont company to do extensive tests of how to fix the hard/brittle receivers with heat treament. They did the draw back process on several hard low number receivers till they were in the 35-40 Rockwell C test range.
They then explain the normal pressure of a M1 round of the time was 50,000. SA tested them with a high pressure round of 68,000 when they were proof fired at SA.
After the hard low number recievers went through the draw back process. They loaded rounds in the 60,000, 80,000, 90,000 and 100,000 range. And planned to fired them at each interval to see if they survived.
All low numbers went through the drawback process were able to withstand up to the 90,000 round, but all but one slightly cracked at 100,000. One was able to witstand the 100,000 round.
For a control comparison they tested normal High numbers receivers. Ones that had nothing done to them, but were high numbers considered safe. It says all high numbers shattered badly at the 90,000 round, except one. It shattered badly at 100,000.
It's interesting to note that they make specific mentions that the low numbers "Slightly cracked" and the High numbers "shattered badly" at the extreme pressures.
It then says in 1938, that the Philly Depot started to explore this option as well, in house, and did have successfully tests of "drawn back" low number receivers that could withstand the 100,000 pressure round.
At the end of the case study they conclude there were issues with both low and high numbers that were failing the rockwell C test, and they should rockwell test and re-heat all receivers that failed the test, both lows and highs.
But like I said, if my memory serves right, they didn't do it long. Maybe a year, and discontinued it. I just don't rememember what was their reason they stopped. It might not have worked in the end. I just can't honeslty remember. But I thought you might be interested in this additional info from the report.
I was taught by an old school tool maker, while leaning the trade myself, that when you harden steel you should always then immediately reheat to to the correct temperature/time etc to give the required amount of temper to whatever you are heat treating. You should always follow the hardening with the tempering operation as soon as possible and avoid any unnecessary delay in the 2nd operation of the process, i.e. the tempering. It was explained to me that any delay between the 2 operations will tend to make the steel brittle and likely to fracture even when it has been subsequently correctly tempered. This kind of information is not likely to be found in text books. I guess a similar thing is likely to occur hear if the receiver wasn't tempered as much as it should have been originally, over time the receiver may well have gone brittle; no amount of further tempering today is likely to correct this.
Thanks for looking further Steve, I have a 1938 dated SA barrel with 368K Rock Island receiver with the dimple from Philly that you helped ID as a Marine rifle.
I would suspect time elapsed and budget was a factor in discontinuing their efforts. Interesting to hear about the drawback process though.
Unfortunately, nothing fixes burnt steel. A Rockwell test will not reveal its presence. Also, a proof test is an imperfect predictor of receiver behavior in a case head failure.
Until the above is understood, along with some of the whys, any discussion of safety is a waste of time. 'Tis a puzzlement that some will draw conclusions about the physics without having at least read Hatcher's account.
Another possible cause of the problems with the Springfield receivers is that they may have been heated to too high a temperature in the initial hardening process. In my experience of heat treatment of tool steels if you get this first part of the hardening process wrong the job is normally scrap and you may as well bin the it and start again. If the steel is significantly overheated over what is recommended there is little that can be done to salvage the job. Different types of steel have differing ranges of temperatures that they need to be heated to to harden them; you need to get it hot enough but not too hot.
At least if your going to play with a suspected handgrenade action do it by remote control in a booth where fragmentation if it occurs will not bother any one may want to some how film the results I would keep the stock or at least put it into a real knackered one. Hatcher had some interesting experiences I must get to grips with that book its been sitting about 3' away from me for months have only graze read it also with his book on the Garand same same. Manns The bullets flight is an interesting book also had a good read of that one and these 2 of Whelen's
to keep this simple.
many have looked real deep into this issue,, more so looking for a feel good answer or a cheering section.
facts.
SHT actions are harder then double heat treat and Nickle steel actions.
they dont fail out of the blue.. out at the range, and boom...or just let loose.
its how the steel handles a simple case head failure. and they usually dont,
were as a DHT or NS action has a better chance of surviving a simple case head failure.
without getting to deep, and kicking a dead horse.. thats the deal in a nutshell.
so, a hardness test would likely not prove anything more then whats already been tested hundreds of times..