Will a carbon steel firing pin break or should it be ok? We had one break and are getting it recreated using a CNC milling machine, they are going to scan the dimensions of the pin perfectly and cut a new one out a block of metal. Just don’t want it to happen again$130 per pin he’s quoted me, and $80 for the scanning job. So $210 all up for one - or he said he will make x10 for $530 and waive the scan fee.Im thinking just get one to try it first and if it’s good I’ll get a few spares made up
some other notes:- he won’t be heat treating the pin, so I may or may not need to do that myself (no idea how to do this: do I just blast the pin with a blow torch and then dip in oil?)- he will be “black treating” the pin. No idea what this means either. Assuming it means chemical bath to colour change it through rapid oxidisation?
>>64637620What type of steel is it exactly? If you can tell me that I can ballpark some heat treatment
>>64637675It just says “carbon steel”How would I heat treat that?
>>64637698Probably something easy to work with like 1080 then. And yeah, no heat treat means the pin will be way too soft. You can eyeball a "cherry red" glow and dunk the pin in a peanut oil quench followed by a 3-4 hour temper session at ~375F in an oven then letting it cool naturally to bring some toughness back. It's not ideal, but it would work. Ideally you are going to send your firing pin batch to get professionally heat treated after identifying the actual steel used, as you can get ideal hardness /toughness with a proper ramp and soak heat treat at the correct temp and time for the steel. Good luck on your project, if it's something rare, you should try and recoup by offloading extras over time.
>>64637721Thanks anon> You can eyeball a "cherry red" glow and dunk the pin in a peanut oil quench followed by a 3-4 hour temper session at ~375F in an oven then letting it cool naturallyI will probably get two pins to start and try this method with one. Then I’ll put 300 rounds through it and see if it breaks. If it breaks I will send the second one off to get professionally treated and try that.If either method works I will order a few spares. Maybe the guy can tell me what steel it is specifically.Never had to heat treat shit before. I was going to try and source titanium but don’t think it’ll be possible hereMy other idea is to put an extra long spring in the firing pin assembly and hope that the counter force from that softens some of the load from the hammer
>>64637698Kinda rough!If its something like 52100 or 5160 it'll heat treat fine in warm vegie oils. An actual carbon steel like a 1075 or 1084 will usually need a bit better quenchant. You could mix up a batch of Glycerine of about 4pts water, 1pt Glycerine and a dash of dish-soap in there and warm it up to about 70C or 160F and then run it through two x 2hr cycles of tempering immediately after the quench as >>64637721 said, Somewhere around 200C or 400F will be fine.Temperature guessing is kind of hardIf you have a couple of house bricks, a darker area to see the colours and a relatively decent blowtorch try to get it into the early orange before dipping it in the quench but that can be kind of hard. I'd recommend something like a wire wheel on a drill after to get the scale off and maybe try to give it a bit better polish with sandpaper later on.Mostly with these kind of things, you're really just aiming to give it that hardness which in turn gives it better wear resistance over time and considerably better ability to handle deformation
>>64637620>he will be “black treating” the pin. No idea what this meansWhy would he feed it fried chicken and wtermelon? I mean, probably not a hate crime, but that seems pretty racist.
>>64637620>making round parts on a milling machine>wants to use a laser scanner for something so simple>he won’t be heat treating the pinYour gunsmith is incompetent. Stay away. This is full of red flags.
>>64637617"Carbon steel" is a broad, generic term, not a precise name.You cannot reliably heat treat a steel unless you have a precise name to find a datasheet with heat treatment instructions.Your heat treatment will likely fail and leave the steel too soft or it might crack during heat treatment.Heat treatment for a firing pin is not optional, and various manufacturers had issues with their firing pins which mostly stemmed from wrong heat treatment.If I was making this part, I would pick a low alloy toolsteel with low distortion and forgiving heat treatment requirements, like AISI O2 Tool Steel (1.2842) then only harden the tip and the hammer face.If you throw the entire pin into liquid for quenching, it will bend significantly, and require straightening after tempering, which not all steels can tolerate, you might get cracking. You could selectively over-temper the middle if you pick the right steel in the first place that allows it by applying a torch to the middle, going to be a bit tricky to hit the right color for the tip and the strike face due to the thickness difference. Can be done but requires some experience and a hand for it.I would be comfortable heat treating such a pin if it was made out of the right kind of steel, something middle of the road and forgiving, something I've worked with before, and then I could comfortably pull this off with nothing more than a blowtorch, sandpaper to get a clean surface to observe oxidisation colors, and a standard kitchen oven for tempering.If it's made from "carbon steel" by a guy who confuses a mill with a lathe, I wouldn't want to touch it.You want to find someone who is qualified to do the heat treatment, and you want to get him involved before you even start making any pins, because that guy needs to advise you on what steel to pick, otherwise you have a high chance of wasting money on this by having these pins made from unsuitable steel.
>>64637721>>64637747If you don't trust your sense of color you can try the Magnet Test. As soo as a magnet doesn't stick to the steel it's hot enough.
>>64637617What does the firing pin go to? Is it one of a kind or impossible to source a replacement?This sounds like a fun gee wiz activity for fun, but I think you're doing a lot to get a pin that will probably cost like 400 dollars in the end
>>64637721>~375FThere's no reason the firing pin should be that hard. It's not a knife.>>64637698I would guess "carbon steel" in this context is probably not 1080 or 52100. If you're trying to heat treat it after machining it to spec, you're really going to need to watch out for deformation.
>>64637617>Im thinking just get one to try it first and if it’s good I’ll get a few spares made updont do this the reason hes offering 530 for 10 is the setup time. him shitting out an extra 9 at that point isnt a big deal.if you buy 1 hes going to charge you 130 a pin when you go back and ask.
>>64637865As a total ignoramus RE all this shit. -Wouldn't this be like a ruler, calipers and lathe sorta thing?Seems stupid to cnc a round part?..But like I said, I know nothing about this shit
>>64639329Calipers, lathe, and file.Figure an hour to make and another 30 minutes to heat treat. O1 steel or similar.Shotgun pins are stupid easy to make.
>>64639334Bet, y gracias, honestly that's what I thought
>>64639334Why would you choose O1? A firing pin needs toughness and yield strength above basically all else. A small piece of pre-hard 4140 or the like would probably be more than adequate, and OP wouldn't have to fuck around with trying to do heat treating he's never done before, and try to avoid deforming the part on top of that.
I've made firing pins before but they were short ones for shotguns. I think I made them out of o1. for heat treatment I tried to make the back end softer than the front end so they wouldn't dent the hammer. idk what your machine shop is doing with a milling machine. a longer firing pin is something you would want to make with a swiss machine. also there's no point in having them blue it if you're going to have to heat treat it yourself since you will end up polishing it off so you can see the tempering colors.
>>64637617How the fuck does anyone competent enough to op a CNC machine not have the wherewithal to break out some calipers and draft this in CAD in literally five minutes? This is in no way a scan job, that's fucking retarded.Also if it's steel this should be a heat treated part, if it's annealed or raw from the mill before milling you're going to get a thousand pops out of it before it's deformed. Price is right for the milling, but you're going to absolutely get a sub-standard item out of this experience OP.
>>64639639O1 is basically what Win and others have used for the past 150 years. It's easy to machine and easy to heat treat without warping.
>>64637620The specific alloy of steel and heat treat are the most critical part of longevity. You have any idea of the original's steel+HT? There's places that knifemakers and whatnot send parts to for heat treat so maybe you can ride that option if you don't feel confident about DIYing the HT.
>>64639706>O1 is basically what Win and others have used for the past 150 yearsI find that hard to believe, for one because O1 hasn't even really been around for 150 years, and also because it's just better suited for things like drill bits, not impact parts.And you can get 6" long, 3/8" diameter hardened 4140 rod from McMaster for ~$3 and not even have to worry about heat treating or deformation.
>>64640556You tried machining a pre-hard rod? Uniform hardness is also not a good thing for a firing pin.
>>64640573>Uniform hardness is also not a good thing for a firing pin.It doesn't really matter if its toughness is high enough.
>>64639701You'd need an optical comparator to get the scallop right, but it probably doesn't matter much>>64637617>>64637620A non heat treated firing pin will not last long at all. Mil spec calls out for 8640 with a salt bath heat, salt bath quench, and air cooling.You should look at a 17-4PH pin heat treated up to H900 (hold at 900°F for an hour, air cool), and that's going to get you RC ~45. You'll find rod stock on Mcmaster for cheap.You could go up in case hardness (HRC 55+) with nitriding, but it depends on your needs.
Holy fuck you are getting hosed. I've whipped out similar firing pins on the lathe in less than half an hour. Just use fucking tool steel like O1 and draw it back to blue (roughly 550 degrees F) after the oil quench.Is it that hard to find a competent gunsmith in your area? Their is absolutely no need for CNC on that firing pin, it's a stupidly basic thing to do on the lathe. And the scalloped section I would just take care of using hand files, the mill is too much work to set up for something that isn't that critical.That's less than a $100 job in my shop.
