Redux: Adjusting and Calibrating the RCBS Uniflow Micrometer

hey folks it's Viejo here the video you're about to see here is one that I'm reposting from my previous channel that had been deleted so if you've seen this video feel free to bypass it and move along to something else won't hurt my feelings at all but I have had some requests to repost some of the videos from that other channel that are not likely to get channel strikes against them so we're going to do that and at the beginning of each of those videos You'll see this very same prologue so you'll know all right happy shooting casting and reloading to everybody catch you later [Music] hey guys it's Viejo here and it is the last week of August here in 2022 we got a nice day outside here on the Central Coast of that great Second Amendment desert known as California I got 69 degrees right now here in the garage 66 percent relative humidity so it's beautiful what we're going to do today is I'm going to show you how to calibrate the micro adjustment on your RCBS or any other powder measure that has a micrometer adjuster on it let me show you what I'm talking about if you have a powder measure like this that's got the micrometer adjustment you probably have been through this situation where we gotta come up with a setting on here that's going to dispense a specific powder charge that we've looked up in our book or where we've worked out previously in our reloading practices and we don't know for sure where we should set this thing okay so maybe we want to load seven and a half grains of unique and we say well I don't know that looks like about seven and a half grains you've got no idea what's going on inside that that rotor here and you go ahead and you dispense that and lo and behold you only got six grains you say well okay it's not enough I'll open this up some more and we go out to here and dispense that and now we got nine grains and then we and you end up chasing that setting back and forth and until you finally arrive at the powder charge that you want well there's a way that we can calibrate this so that we'll know almost exactly where to set this to get the charge that we want we can't do it exactly but we can come up with a very close starting point and further we can figure out just how many more of these tick marks we need to adjust right or left to get that extra tenth of a grain or take that extra tenth of a grain off right so that's what we're going to show you about today this is a very simple procedure and we can do this for just one powder but the information that we get by doing this for one powder we can carry that forward and use it for any powder and I'm going to show you how to do that it's very simple we're going to start this by making sure everybody's on the same page about how these work okay the the whole body here is called the rotor all right and inside that rotor we've got a piston and there's a hole in there that we're going to refer to as the cylinder okay this one happens to be out of an RCBS um powder measure just like the one you saw a moment ago this one's out of a Hornady okay they behave the same way parts are put together a little bit differently okay this one the Piston slides out of there nice and easily just like that okay and again we've got a cylinder in there okay and the way they work is that piston just Moves In and Out of the cylinder with a screw adjustment okay that we can turn turn in and out and adjust the depth of that piston so it's just like the piston and cylinder in an automotive engine okay it's the same principle okay we change the volume of the cylinder by moving that piston up and down or back and forth through the rotor all right the Hornady one we kind of like this one because it's got just a simple snap lock that holds our piston in place okay that's really handy and that just snaps in there the RCBS unit has to be threaded in and out of there okay these two units do not have the micro adjustment on it this one out of the RCBS does have some graduation marks on there okay and those can be used in a fashion similar to what we're going to show you with the micrometer the Hornady does not have those adjustments however right there let's see if he can focus in on that a little bit more right there is a reference Mark see that okay so you can count the number of turns on that reference Mark to make your adjustment but that's all there is on this one okay Hornady does make a micrometer adjuster for this which I have some where I bought it and I put it away and haven't ever used it and I couldn't find it for the video but I do have one somewhere all right the first thing we need to do is make sure that our adjustment screw is properly set and I have this one intentionally upset right now so that it's in the wrong spot okay and the first thing that we're going to do is we're going to move this up so that it is horizontal across the body of our powder measure here okay and that's so that as we adjust the Piston we don't adjust it up through the slot in the bottom of the hopper here okay we want it straight across because what we're going to do is we're going to turn our adjustment knob here until we feel the top of that piston contact the back side of the housing behind here and you can feel it and hit over there and you don't want that rubbing there you want it to be very very close and then maybe back this off just maybe one tick here so that your rot rotor will rotate freely and not rub okay and that's as far as you go with that then the next thing that we're going to do is we're going to loosen this set screw in here and loosen it way out okay not as so far out that it comes out of the housing but far enough out so that it won't contact our piston here because we're going to move this and we don't want to change the adjustment of that piston so get it good and loose just so that it doesn't fall out and again still holding this horizontally now push that adjustment all the way up as far as you can okay and then we're going to rotate it and this should not turn our adjustment screw at this point okay we're going to rotate it until our zero lines match up exactly okay zero here and zero on our reference line right there okay so if that zeros out our scale now we can re-tighten the set screw down here bring that up where you can see it okay and we get this pretty snug guys because it's just there's no flat or anything that's the back end of our piston that goes up into the rotor and we there's no flat or anything for that set screw to rest against it's just going up against this side of that Rod so it needs to be reasonably snug okay so that's our proper adjustment now okay and this will now turn as you can see it's turning our maybe you can't see it turn there you go you can see it turning our piston and backing it out all right so that part is done you can see how much you know just a couple of ticks of play there and that's fine okay just like that if I go one more tick over mine starts to drag so about one tick off the drag Mark that's where you want to be if you look at your own powder measure you may see a couple of washer looking things in here okay that would look like this if you take them out and all those are are shims and there can be anywhere between none and three of those set up in here and all those are four is to establish the position of your scale here so that's in a it's in a readable spot in other words if you put this stem all the way in there and tightened it down and that scale was all the way around behind there it wouldn't do you much good because you couldn't see it so you would come in here and put a shim or two in there such that the tight spot leaves that scale at that point so you're free to add or remove those shims as necessary to get that scale where you want it okay the next thing we're going to do then is we're going to fill our Hopper and we're going to do this with the baffle out okay all right for this experiment we're going to use a nice ball powder Winchester 231 and we've got our adjustment knob turned out all the way exactly to the 10 mark all right what we're going to do is we're going to see how much powder by weight is thrown by this much and then we'll divide that by 10 and we'll be able to figure out what the gram weight for 231 is for each of these major divisions so I'm going to go do that hang on all right so I'm going to settle my powder here just kind of tap that down a little bit I've got my pen teared out on my scale so I'll drop a couple here quite a bit of powder so make sure you give it time to drop completely okay so I'll go away that and that comes in at 37.7 let's do it a couple more times and take an average 37.7 again you know I spill some we won't count that one and 37.7 again so good job there uniflow so I think we'll call that good at 37.7 grains for 10 units on here that means that each of these units would be equal to 3.77 grains of 231 and for reference sake these smaller divisions here let's zoom in on this a little bit better for each of the divisions around here there's a hundred of them between each major division here so like between seven and eight one revolution around here is 50 of these tick marks and that takes you up to the seven and a half and then one more Revolution is 50 more takes you all the way up to the eight Mark so there's 100 of these ticks between each numeral here on this scale okay so at 3.77 grains of 231 from between any two of these numbers point zero three seven grains for each one of these ticks so they're not worth too much but that's handy to know okay so let's see how we did I've got this adjusted now to one mark on there and that should by All rights be 3.7 grains 3.77 so let's see right there okay so we did pretty good here's what we do with that information remember that I all I did was I found the weight of 10 units on my micrometer divided that by 10 and I found out that each unit on my micrometer was worth 3.77 grains of Winchester 231 and so to figure out the proper setting on your micrometer you just you take the desired charge and divide that by this factor and I've just made that term up okay for this number right here I'm just going to call this my factor for 231 3.77 grains per unit uh so for example say I needed 4.2 grains of 231 where do I set my adjuster well the setting would be the charge divided by that factor so 4.2 divided by 3.77 this is telling me that out somewhere at about 1.11 on that scale should give me my 4.2 grain so let's try that see if it works I've got my little scale teared and we'll set our micro adjustment for 1.11 there's 1.0 1.05 1.10 right about there okay I apologize for getting in the way but I'm going to go ahead and dump my charge here and look at that okay all right I just got lucky here usually didn't come out that close but we nailed it but what about other powders this is these numbers this you know 3.7 grains between these two marks that's only good for 231 well it turns out we can use our earlier value of 37.7 grains for a full 10 units we can use that coupled with another piece of information to figure it out for every powder without having to do all these measurements there is a property of smokeless powders called the vmd which stands for volume measure density and what it is is how many cc's are there per grain of powder in the case of Winchester 231 it turns out that there's .0931 ccs for each grain of Winchester 231 and that number is different for every powder it's a property of that is specific to every every given powder that we have all right and from this formula vmd equals CC's divided by grains we can do just a little simple algebra here and find out that any particular volume in CC's can be found by multiplying the vmd for that powder times the grain weight of that powder so that turns out then that our 3.7 grains of 231 per unit on my scale on the powder measure works out to be equivalent to 0.34 CCS okay that would be the volume of that cylinder represented by the difference between any two major divisions on my micrometer scale and this number doesn't matter what powder you've got okay if I move my micro adjuster from unit 1 out to unit 2 it will have increased by 0.34 CCS now I did this for several powders and the cylinder in my particular rotor actually comes out to an average of closer to 0.32 cc's per unit but that's not much different than this and we're only looking to get close anyway okay so this number here is important now that we found out the value in CC's between any two divisions on our micro adjuster scale we can turn this around with our vmd number and figure out our factor that we had remember Factor we can come out and find the factor for any powder really quickly and we don't have to put a bunch of powder into our powder measure ever again okay and we can do that because Richard Lee gives us a table of the volume measured density it's on page 673 of his book okay it's actually two pages worth okay for all of those powders and this is also available online I'll leave a link it's on Lee's website and you can download it or just go look it up all right and I went ahead and printed the whole thing out so that I don't have to look it up and I don't have to jump on the book okay so I printed this whole thing out so let me give you an example let's go up here and look at unique and we see that the volume measure density is 0.1092 okay so here's what we do with my vmd formula actually I derived this okay and we can find that our Factor remember Factor that's like our multiplier value for each powder it's going to be the unit volume of one unit on my adjustment scale divided by the vmd for that powder so here's an example the vmd for Unique from my chart was 0.1092 I found over here by experimentation that my uh adjustment is actually worth about .32 CCS for each unit on my scale so I simply put that unit volume here of 0.32 CC's over the vmd4 unique and I find out that my unique Factor is 2.9 so all I have to do to find a specific charge of unique is I would divide my charge by the factor in this case if I was looking for 4.2 grains of unique which is kind of a Wimpy charge for Unique but I would divide that by 0.29 instead of 0.377 okay so let's let's give an example for seven grains charge of unique okay what I would do is I'll take my seven grains and divide that by my factor of 2.9 and I get a setting of 2.4137932154698379 okay 2.4 all right let's see if that works all right we've got some unique in here now and I've got my scale set out to just a little past 2.4 so let's see what happens here okay so I've got my pens uh is teared and we'll see what we dropped and remember we don't expect it to be exact we got lucky on the 231 but we want to be close let's see what happens within a half a grain okay now if you remember each of these divisions each of my each of my tick marks I mean is 1 100th of a division that means that it's also 1 100th of that 2.9 Factor so I think I'm going to be needing about somewhere between 18 and 20 more tick marks worth of adjustment on here as I spill powder all over the place so I'm going to run this out 5 10 15. about 20 more divisions okay and there I am okay what prompted this video was I had another chart here taped right onto my powder stand and it was getting so ratty that I couldn't hardly read it anymore so I wanted to make a new one and then I got busy on the computer and I ended up taking all of those vmd values from the lease site and putting it into a spreadsheet and just go ahead and calculating all of these numbers now you got to remember that when we do this for one particular rotor the values we get down here are only good for that rotor if you also have the rifle rotor which has a bigger cylinder in it these numbers are not good for that you have to go do the same process with that one to find out the volume per unit okay on your other rotor but I use this one mostly so if I get a new powder then I can just refer to this I've got them all done on there but these are the ones I use most often so that's why it stays taped right there so all you do you know once you get the little Factor figured out for each of the powders you're going to use you just look at that factor number you know whip out your phone with the calculator do the quick calculation takes two seconds make your adjustment and you're there okay at least you're close all right guys there you go I hope you can follow all of that it really isn't all that complicated you know you can screenshot those paper pages that I showed you with the formulas on it and print those out or just copy them off they're real simple not that hard to do I will put a link as I said for the page that Lee has for all those vmd values if you don't have the lead book they're already in the lead book um and I I think that you can use a similar process on Powder measures that don't have the micrometer adjustment itself as long as there are some kinds of graduation marks on there you can kind of use the same process and remember that this is not going to be 100 accurate there's a couple of bugs in this whole system one is that the Pistons that are in there are not exactly cylindrical okay they got kind of a domed end on them and that upsets our volume calculation a little bit plus the powder manufacturers have some variance from a lot to lot in the powders but with the vmd is actually going to be so vmd for you know this lot could be one value it could be slightly different next time so there is that but all we're trying to do is get close and not be five grains off on a nine grain charge okay and I think you can see that that's uh that that'll work all right I hope you got something out of that but for now that's all she wrote

Channel: Viejo

Views: 4,971

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Id: jstavU9rZCw

Length: 26min 22sec (1582 seconds)

Published: Sat Nov 19 2022