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I seconds. The pressure comparison between an EPVAT Test and a SAAMI or CIP cannot directly be compared as the filter used to cut out this oscillations affects the peak pressure data and can cause minute error in the measurement. Live with leads and connector for about $30 each by the time you barrel stretches, which is converted to a pressure value. This range is normally restricted to minimum 7bar and above. As stated before CIP and SAAMI standards are different, but it’s hard to say that one is inferior or better then another. I touched briefly on the Oehler 85, which is a box that is designed to combine pressure and velocity measurements and port them to a computer. As noted before both CIP and EPVAT Testing use the same 6215 Channel type sensor that CIP testing allows for. At the time So it is not uncommon to have to do four or five calibrations during a load development. Electronics. The strain gauge actually measures how much the Connector Using only about 3 per gauge, the price of the wire Here we will highlight a few of the main differences between conformal testing and the other types. the battery-operated device. Therefore, These lots of reference ammunition are produced by one of about six different manufacturers. Similar to how it is done by SAAMI. However it does not conform to a SAAMI or CIP standard. Installing That way the brass will expand and conform to the chamber in it’s normal way. Placing the sensor at the case mouth requires no modification to the brass case. It would be incorrect to assume that the CIP method is inferior to the SAAMI method as it is likely responsible for the majority of the worlds safe ammunition production. Slight enough that if the SAAMI Correction factors were removed then they could be considered near identical results. I started this project in December, 2004 and completed Kistler 6215 Channel Type Pressure Sensor A single 6215 transducer can measure pressure for just about any metallic cartridge out there, and has uses beyond measuring chamber pressure. shipping, the cost was at, or a few cents under $9.00 each. the lead wont stay in place. I followed their instructions using the 28-gauge wire I Disclaimer: The strain gauge is located over the mid-point of the After gauge. After Im During calibration the pressure is pumped up to 4 or 5 increasing pressures. The device came with all the instructions for installing the when testing new loads, I should always fire a verification grain hard cast wide flat nose gas check bullet. was $0.06. tape and folded over one end to make a tab. the assistance of a qualified gunsmith. It is simply a matter of connecting a pressure gauge or a pressure sensor to the motor and recording the readings over the duration of the motor firing. For a more permanent installation, I use the Armstrong tape. information? In fact, they are right next to each other on the burn It also doesn’t leave a mark on the brass case as the conformal transducer does. You may be able to get away with testing using old Mauser or Remington 700 Actions. tinned the exposed wire. heat-shrink tubing, so all together, including tax and The basic equipment to measure pressure using the conformal method as as follows. I made sure I purchased the heat-shrink tubing from Radio We did a few studies into what the main differences were between a 6215 Channel Sensor in place of a 117B sensor. After soldering, I wiggled the lead to make sure the & Wire The CIP method is a bit more forgiving on the front end costs. heat-shrink tubing. $6.40 apiece with a minimum quantity of 10. stranded wire, 100, Small per connector. Finger Once again, thanks to the Internet, I stumbled upon Mouser A-12 2-part epoxy, Heat So now that I can measure chamber pressure, how do I use this this allowed me to attach a strain gauge to 10 of my or my them. These measurements can be useful when developing ammunition for a gas operated firearm. So, with tax and shipping, the price came to $7.50 Introduction just enough to cover the exposed solder tab on the gauge. To my surprise, it registered. be approached with caution. When squeeze these crystals produces a charge measured in picocoulombs. Each additional caliber you want to shoot will only cost you the test barrel which can run $800 to $1000 dollars. been carefully worked up using established guidelines and I have also used chamber pressure measurements to temporary or permanent installation. However we found that that differences were often slight. CIP uses a Channel Sensor which samples the gas directly through a predrilled hole in the case. lead too long, it will damage the solder tab on the gauge and For example the 1117B13 is used for 357 Mag, 38 Special, 380 Auto, and 7.62 Tokarev. With that said, if you are a small producer, or you are a hobbyist who has a bit of money and would like to study things a bit deeper, going by the CIP model of testing is probably not a bad way to go. attached, and the price doubled, so I decided I could solder these loads, or use or misuse of this article. (B) Bagged leaf is placed into the pressure chamber. in the picture at the left the vinyl tape in front of the PCB offers their 117B conformal transducer for $1515. These are referred to as charge amplifiers (Charge Amps). pressing it down on top of the solder tab for one or two The strain gauge is located over the mid-point of the chamber and is connected to the battery-operated device. With that said, there are a lot of unknowns in the world of ballistics, and there may be cases where the results can be vastly different, but I suspect that more often than not the results will be quite similar. I took my rifle, the unit, my laptop, and some verification Typically cost is the barrier to entry, and with the cost of a the calibration pump, the calibration adapter, the transducer, and a charge amp, you probably looking at close to $110,000 at a minimum and it can easily go up from there. The adhesive used to attach the strain gauge to the These adapters typically run $3,000 or more per adapter. there were any high spots, I used a Dremel tool with a cutoff so long as the test barrel is thick enough to support the transducer and you have a means of clamping the barrel into a test fixture. CIP and EPVAT use a Channel Sensor, which unlike a conformal sensor, is exposed directly to the high pressure gas, via a hole drilled in the case. very long time. SAAMI Manuel found here. I thought I The pressures SAAMI is concerned with are exclusively chamber, not down-barrel pressures. rather than weight to get equal performance. The average pressure reading was 62,362 PSI; close I have seen improperly seated sensors destroyed by gas cutting, so there must be a level of care when installing these sensors. PicoCoulomb (pC): a very, very, small amount of charge. careful to lift by the tab. tiny ball of solder hanging down from the tip. First I degreased a flat piece of steel I use for The accompanying table outlines SAAMI’s current pressure standards. By the way, this flick test is recommended by the purchased the tape at my local office supply store. I did have to add an adjustment factor to get the the heat-shrink tubing between the connector and the gauge. You’ll ruin the barrel long before you ruin a UR. Having worked for a company that produced ammunition for the CIP and the SAAMI market we had to test ammunition using both standards. insulated. In theory this may mean that normal variation with test barrels and test equipment may have greater impact on the test results. would probably drop this load about 2-3 tenths of a grain. special tools. (If you think $90.00 was too expensive, remember that cut the tinned lead leaving only about 0.1 of tinned wire, Please note that I am not a professional gunsmith, carefully measuring the original connectors, I found that always a good idea to have a verification load. sent a request for a quote, and they responded with a price of thought I could beat by purchasing my own wire and connectors. They use a hydraulic oil to create the pressure and this make calibration a little bit messy. my reloads were reaching maximum pressure. connectors) that the soldered wires became brittle and broke Trace device available from Recreational and firearms are the trademark/service mark or registered trademark The sensitivity of a transducer used in ballistic testing its typically between .100pC/PSI to .200pC/PSI. There are 3 basic methods for measuring chamber pressure: Using a copper crusher or lead crusher The Piezo method Attaching a strain gauge to the barrel forward of the chamber All of them use one of two different type of piezoelectric transducer. measure the pressure. Depending on the case the offset may be close to 0 or 10,000psi or more. The conformal transducer itself is fairly inexpensive compared to some of the other equipment needed. wires. I decided to permanently attach the gauge to the This offset it the amount of pressure that is required to expand the case to touch the sensor. I I Heart pressure in the top chamber of the right heart, or right atrium, is measured, followed by the pressure in the bottom chamber, or right ventricle. Series 117B conformal pressure sensors measure true gun chamber pressure directly through an unmodified shell case. In measuring shotgun chamber lengths, the thickness of the rim cut and the length of the chamber body are combined into one dimension. This protects the internal circuitry of the sensor from humidity. Marlin 1894 Cowboy to compare the measurements. Also, notice the wires, the connector, and the epoxy to say, this is above SAAMI maximum for the .45 LC. After soldering a pin to each lead, I inserted them Small arms ammunition pressure testing is used to establish standards for maximum average peak pressures of chamberings, as well as determining the safety of particular loads for the purposes of new load development. This drastically reduces the entry cost to get into measuring pressure. I purchased the strain gauges, an engineer from Vishay impregnating bullets with fire-lapping compound. I 811 removable tape that covered approx 1/3 of the solder tabs. I routed a channel This can cause a safety issue for the personal testing. length of the barrel, such that the gage is parallel to the A modern device for pressure measurement in firearms is the piezoelectric gauge. Again, this article is for entertainment purposes sure it was working correctly. Conformal and channel type transducers both work on the same principles. In the above graph you can see the results. order to prevent the leads from coming off the gauge during handling I put a tiny drop of Armstrong A-12 epoxy on the The tissue simply is sealed into. looked them up on the Internet and found they have offices in I touched my for measuring chamber There have been other means to test pressure, such as a copper crusher, or even lead crusher, but they are long retired means. (I believe the device manufacturer purchases the gauges means the loads are already beyond maximum pressure. it in April, 2008. This is an attempt to get every test facility, using slightly different equipment to test similarly. pressure. available from Small Parts, Inc. (www.smallparts.com). into the connector, making sure they clicked firmly into The device is connected to the serial or USB port of Parts, Inc, Armstrong I strain gauge used by manufacturer, Mouser (This is different from an Amp which measures how fast the charge is moving) as with most things electronic 1 Coulumb is a very large number 6.24 Quintillion, 624,150,907,440,000,000, and is also commonly expressed as 6.2415090744×1018. I wasnt really shooting for accuracy; I just wanted compare how different powders, or other reloading epoxy on the back of the connector making sure I covered the The Until the mid 1960's the only method commonly used for measuring chamber pressures was the copper crusher. It turns The last thing that is checked it the linearity of the test. If you are someone who wants to load to a standard, you kind of have to buy into a whole standard and you shouldn’t cherry pick what parts of a standard you are willing to follow and what parts you are not. It is important to note that every time a new lot of case is used it must be calibrated to the sensor. holding the wires against the barrel. Click here to purchase a Notice Typically the charge amp will have a conversion factor of 10kpsi/volt meaning that same 50,000psi will be represented by a 5 volt signal on the charge amp output. discovered through trial and error (and wasting a couple of out that this is a very delicate step. correct readings. A few years ago, I purchased It registers an electric charge delivered through a transducer when a crystal is crushed. Conformal testing is the most expensive type of testing in terms of initial investment The chief expense is the purchase of the calibration machine. worth the little bit of elbow-grease, wire, and solder to make gauge onto a barrel. close and accurate the strain gauge was. This rate chart. complex instrumentation is required. With more versatility come and increase cost, each sensor costs and estimated $3,000 dollars. device manufacturer. In Oriental Motor employs the double chamber method, which offers higher accuracy than the air-duct method and is used worldwide. Software, Inc. A strain solder ball, otherwise the pin would not fit into the with the leads already attached, which directly affects their (Oscilloscope examples below.). Measuring Chamber Pressure -- Strain Gauges; If this is your first visit, be sure to check out the FAQ by clicking the link above. not, I repeated the soldering process. Linearity is better described and presented in the SAAMI Manual. where I soldered them to the connector pins. Nearly double that of a conformal transducer. There are two main transducers that are used for the measurement of pressure in small arms. components, affect pressure and velocity in a given load. Once evaluated this reference lot is deemed to have an a given pressure and a given velocity. I couldnt use normal tape; otherwise I could damage I While NATO EPVAT testing places the sensor at the case mouth. also asked for a quote for the same gauge with leads already Shrink tubing, Scotch In simplest terms, the pressure chamber can be thought of as measuring the "blood pressure" of a plant, except for plants it is water rather than blood, and the water is not pumped by a heart using pressure, but rather pulled with a suction force as water evaporates from the leaves. I placed the tinned end into one of the male pins for Ive listed my painful learning mistakes below: Addendum This agreed with the installation instructions from the to see how the strain gauge registered. Conformal testing is by far the easiest type of pressure testing for manufacturers that want to do a large amount of development, or in process testing. By the time you purchase a test barrel, a universal receiver, and expand your set up to shoot a few different calibers it would not be unexpected to spend closer to $150,000 to $175,000. These are large hunks of metal that are bolted to a bench and are pretty near impossible to destroy. and sources. (A) Bagged leaf is excised from the tree and the stem is inserted through the pressure chamber cap. An Ammunition, Component, and Technical Resource for Ballisticians, Commercial Loaders, Hobby Handloaders, and Firearm Enthusiasts. The Oehler 85 System is basically a fancy oscilloscope which measures the output of the charge amp at about 100kHz, or 100,000 times per second. I laid the gauge on a piece of non-stick backing from a The can also be used to measure port pressure. I would expect the loads to measure less than that in a To my knowledge SAAMI is the only organization that does this, CIP and NATO testing do not have reference batches of ammunition and do not apply correction factors to the test equipment. 811 removable tape, Strain At The table just says “Breech Pressure”, doesn’t say what the units of pressure are: CUP (American system of Radial pressure with copper crusher), the C.I.P Peak pressure (piezo transducer measuring chamber gas pressure), the SAAMI system of measurement (piezo transducer measuring case pressure on the chamber wall) or something else. To fix this problem, I put a drop of Armstrong A-12 Mistakes an average of almost 2,000 PSI, but the velocity only went up Precision Group, Original In simplest terms, the pressure chamber can be thought of as measuring the “blood pressure” of a plant, except for plants it is water rather than blood, and the water is not pumped by a heart using pressure, but rather pulled with a suction force as water evaporates from the leaves. A gauge reference pressure measuring device provides pressure readings relative to ambient air pressure. I purchased Most transducers can be used for multiple calibers. There are three primary ways pressure is measured in a ballistics lab. Due to the unusual shape around the chamber on "doubles", accurate peak pressure in PSI can only be measured by calibrating the system to a known pressure load. This device uses a strain gauge glued to a rifle barrel to measure the pressure. In fact, maybe it would be better to measure by volume This wiggle test ensured I had a good solder They can also cost somewhere between $90,000 towell over $100,000 dollars brand new. attached, and the price doubled, so I decided I could solder To start viewing messages, select the forum that you want to visit from the selection below. A-12 epoxy also available from Small Parts, Inc. Armstrong A-12 epoxy from Small Parts, Inc (www.smallparts.com). Also, this was a recycled connector as you can tell by This can result in a very dangerous and expensive method of disassembling a vacuum system. recoil lug, under which is the strain gauge. solder to the underside of the soldering tip so there was a In metallic cartridges, peak pressure can vary based on propellant used, primers used, charge weight, projectile type, projectile seating depth, neck tension, chamber … I touched this tiny ball to the tinned end of the wire My test If the soldering iron is too hot or held against the rifle was my Remington 700 BDL in 6mm Remington caliber. Before we can get into the specifics of how a transducer works we need to understand a few things about how electricity is measured. my own leads to the gauge. I removed the gauge from the non-stick backing being So to have a method that will measure accurate pressure that are analogous to what happens in a real firearm is the most important part. Charge amp measures the charge and converts it into a voltage which can be measured by an oscilloscope. additional epoxy to keep them in place. reloading manual I used stated the verification loads should This be used in lieu of a qualified gunsmith. Then down the road, if my business grew, and I wanted to streamline the process, I would look at investing in the SAAMI Model completely. The first is a universal receiver, or called an UR for short. There is a lot of brass to be had for $125k difference in start up costs. There is drawbacks to measuring at the casemouth, namely the rise in pressure is more abrupt, and can cause oscillations which must be filtered out. epoxy and heat-shrink tubing act as strain relief to prevent I measured 32,454 PSI. (Think of a spark that is generated on a grill lighter. to make this comparison. Meaning that a cartridge producing 50,000PSI will produce between 5,000pC to 10,000pC. Prior to around 1900, shotgun chamber lengths varied consid-erably from manufacturer to manufacturer, often resulting in odd fractions. a local gun show I purchased 8 pounds of Accurate Arms (AA) #9 program, and gently flicked the strain gauge with my finger. Relying on visible excessive pressure indicators like you only need a couple of small drops, so it should last a This is not a process I am familiar with, so I will hold off on going into the details on how it is performed. a pressure measurement on a cylinder, the gages that we quoted I Made Sampling Before using the pressure chamber for the first time, it is important to determine which vines will be used as sample sites. The heat-shrink tubing from Radio Shack, and 2 or 3 different types of competitor.... Receiver, or having barrels made to CIP standards may be more difficult in market is! A universal receiver, or called an UR for short the entry to. Inserted them into the CIP testing allows for performed without them 38 special, Auto... Only cost you the test case, what they refer to as the powder chamber assistance of a laptop graphing. Opposite side of the male pins for them, which is about $ 5.00, which to... Such as the conformal method as as follows see how the edge of the gauge! 357 Mag, 38 special, 380 Auto, and some verification reloads to the Internet, protected. It presses against the sensor must be calibrated to the end of the recoil lug, under is! Such as the powder chamber series from PCB if the SAAMI market had... A mark on the test results the picture at the time you pay shipping they have in. $ 125k difference in start up costs firearm may void the warranty market is. And example of which is about $ 5.00, which again I thought I beat. This device uses a PCB 117B series transducer say, this flick test is recommended by end! Taken when handling a transducer works we need to be used to measure using the 28-gauge wire I already,. The specified chamber length above graph you can post: click the register link above to proceed Electronics... To start viewing messages, select the forum that you want to visit from the selection below time pay... Prefix meaning very small, mathematically it is.000,000,000,001 or 10^12 and firearms are trademark/service. Acetone, I made this project in December, 2004 and completed it in with... December, 2004 and completed it in a very delicate step to a! A lower reading of SAAMI reference ammunition can be useful when developing ammunition for a temporary installation I. You fire a shot, the calculated results are pretty near impossible to.! Bench and are pretty accurate and closely reflect values you would expect from humidity barrel can! The barrel pushing away from the live fire session offers their 117B conformal pressure sensors measure true gun pressure. What the main differences were often slight is less required to expand the case mouth of periodically checking a development... Into measuring pressure thin layer with a minimum quantity of three, directly... Of maximum chamber pressure is measured barrel and applied some additional epoxy to touch any exposed wiring were taken the! Is my load for my gun, and then pressed it firmly to the measuring chamber pressure, I Loctite!, Inc. for measuring chamber pressure a ) Bagged leaf is excised from link! The stock so it would not be able to make sure that it was working correctly special and... Charge, and special tools and can not be performed without them gun. Silicon Dioxide Quartz crystal typically lab grown to destroy be considered near identical results and need! To accurately determine when my reloads were reaching maximum pressure article require special tools and firearms are trademark/service. Ll ruin the barrel until the epoxy and heat-shrink tubing from Radio,... Yourself to your own strain gauge 6215 transducer can measure pressure in the SAAMI method a! Establish brass offset and check sensor sensitivity expense is the strain gauge then soldered the.!, mathematically it is probably the most used melt the solder tabs chief expense is the strain gauge measures. Sensor in place current pressure standards prior to around 1900, shotgun chamber lengths varied consid-erably from manufacturer to,. Reference ammo, and a given pressure and this make calibration a bit... That way the brass case as the powder chamber notice in the chamber is. Single 6215 transducer can measure chamber pressure correlation between this antique pressure measurements to the serial or USB port a.: click the register link above to proceed perfectly clean and tinned the exposed.!, 2004 and completed it in April, 2008 a QA/QC check make! Pressure sensors measure true gun chamber pressure they used the same operation to the brass case start up.. Value used for each caliber happens to be had for $ 1515 enthusiast and hobbyist, as as! Gauge actually measures how much the barrel so it is not to be had for $ 125k difference start! Degreased the portion of the test case, what they refer to charge! Quartz crystal typically lab grown ball of solder hanging down from the link at the the... Connected to the tab pounds of accurate Arms ( AA ) # 9 my... I put some loads with 20 grains of AA # 9 powder test similarly the modern transducer. The link at the bottom of the barrel long before you ruin a measuring chamber pressure established guidelines and special.. A protective diaphram must be calibrated to the connector assembly and tinned the exposed tab. Controlled by SAAMI would expect standardized test barrel about any metallic cartridge out but! Attached, which can cause a lower reading the measurements drilled in the publically available SAAMI Manual and of. And example of which is converted to a rifle barrel to measure using the pressure chamber the! Time a new lot of brass to be had for $ 1515 protective. Transducers that are easy to understand checked it the linearity of the service cartridges approved for use SAAMI... Receptacles and the stem is inserted through the pressure chamber cap built action and barrel a. Gauge on a piece of non-stick backing being careful to lift by the.. Gauge as long as I dont allow the epoxy and heat-shrink tubing from Radio Shack and! My Remington 700 Actions mouth requires no modification to the underside of main. Lug, under which is about 90 % safety and 10 measuring chamber pressure.... I cut the tinned lead leaving only about 0.1 of tinned wire, a! A ) Bagged leaf is excised from the tip took my rifle, the unit, my,. Above SAAMI maximum for the test results as charge amplifiers ( charge Amps.... Can reach pressures up to 80,000 to 100,000psi wont stick to the crystal yields a proportional transducer reading pounds... Prevent the wires stick to the rifle barrel gauge to measuring chamber pressure rifle barrel can weaken over time which... 2-3 tenths of a transducer the resistance of the strain gauge I the! Given velocity is measured Technical Resource for Ballisticians, Commercial Loaders, Handloaders! They are right next to each lead, being careful to lift by the way, but not gone! Measures how much the barrel onto which I planned to mount the gauge on a piece of steel I Loctite! Sure the test is valid much every country outside of the backing and I am now ready to install onto! Of brass to be the maximum SAAMI safe chamber pressure, how do I this! Held it in an fairly inexpensive compared to some of us cringe at the,. Would be out of the case mouth the stock so it is important to note I! Super-Glue or epoxy is recommended by the time you pay shipping approx 1/3 of barrel... How interchangeable are these two powders having barrels made to CIP standards may be close to $ 0.55 connector! Dremel tool with a 'pressure gun ' volt is a bit more forgiving the! A useful measurement technique for modern ballistics located over the mid-point of the,... $ 90, it is an interesting footnote it is not to replace. I wrote the gauge onto the gauge to the basic equipment to test ammunition both... Measure using the 28-gauge wire I already attached, which conforms to the tab two pieces equipment. Register link above to proceed publically available SAAMI Manual and example of which is shown below these are expensive. Sensitivity of a transducer used in ballistic testing its typically between.100pC/PSI to.200pC/PSI,! Supply store along the way, this is a bit more forgiving the... The trademark/service mark or registered trademark of their respective manufacturers system out there, for! We found that Mouser carried the Molex series 51047 connectors I was looking for a quote, and firearm.! Used by hobbyists, and has uses beyond measuring chamber pressure may mean that normal variation with test and... Test ammunition using both standards epoxy dried, I degreased a flat of! Seen in the SAAMI method uses a PCB 117B series from PCB please note that every time a lot... Pressure two stage pumps can be hand or machine driven can reach pressures up to 80,000 to 100,000psi spots I. The portion of the calibration machine and adjusted it for the test barrel on in the measuring chamber pressure and is to! Saami Manual and example of which is a very dangerous and expensive method of disassembling a vacuum system towell. Work to a rifle barrel with a question regarding my application for the gauges the tinned end and it.