Within firearms, chamber pressure is the pressure exerted by a cartridge case's outside walls on the inside of a firearm's chamber when the cartridge is fired. The volume of a cartridge case is equal to the chamber volume minus the volume of the metal making up the case and primer, minus the volume of the extractor groove. In this thread I am hoping to focus on the benefit, perceived benefit, or if it is a … This could help answer a few questions about the overall experiment and to inform future experiments with larger sample sizes. As in the AMP Annealing article, they too identified that most weight variation is in the case head. And as far as I know, setting a measure for 100 grains of BP will get you 72 or so grains of pyrodex, but the two charges will be ballistically similar. To get a better sense of how much it mattered to my readers, I asked a few questions about brass sorting in a survey. I use a syringe with a needle instead of a dropper. There are YouTube videos and write ups on this subject. I use my .45 acp case as a measure for my Ruger old army for plinking with 3F Goex BP. The case and water here weigh 304.3 grains.   The volume is the measured difference in weight between the empty case and filled. Therefore, any weight variations with those cases must be in the case heads. Battery and protective storage case included. QuickLOAD relies on case volume as a critical dimension for its internal ballistics simulations. Personally, I expected there to be less variation in weight at this point – this data does not indicate that, however. In his Measuring the Case article, on his Rifleman’s Journal website, German reviews the tools and techniques required to measure everything from case overall length to case neck concentricity. Isopropyl alcohol (99.9%) was used because it has a number of benefits over distilled water. Thanks for taking the time to read this article! I enjoyed writing it and learned a lot in this process and I hope that you did too. ) to that of distilled water ($W_{\text{H₂O}}$ If you have any feedback, you can email me directly if you don’t prefer to use Reddit or other social media. The cartridge headspaces on the mouth of the case at the L3 datum reference. ). _gaq.push(['_trackPageview']); Some use water, some use powder, some measure case weight, and spend a lot of time sorting brass with the hope of improving accuracy. There are several options for case trimmers from those that are hand operated to a variety of trimmers powered by electric motors. Finally, just 12% of the shooters said they weight-sort their brass. Figure 1 illustrates This liquid volume measurement method can be practically employed to about a 0.01 to 0.02 ml or 0.15 to 0.30 grains of water precision level for firearms cartridge cases. {:.hide-on-med-and-up}. If these estimates are correct, then a 0.50 grain (H₂O) case volume variation translates to a significant +/- 14 ft/s muzzle velocity spread. One version will work with all small-primer-pocket cases, while another works with all large-primer-pocket cartridge types. You may not reproduce original text or photos without advanced permission in writing. © 2017-2021 Ammolytics, All Rights Reserved. What these charts made me realize is that I had set up my resizing die to bump the shoulder back based on a once-fired case. So, if it’s both important and difficult, then there’s value in alternative measurement techniques which are reliable, deterministic indicators of case volume. and .22-250 AI versions. Segregating cases by headstamp is as careful as we need be. The following questions may help you to better understand the complexity: I didn’t have a large quantity of cases to start with, from which the heaviest and lightest could be used for the experiment. While reading this article, I only ask that you keep an open mind. But when you see a cartridge like 7X57mm, 8X57mm, or 6.5X55mm, this is what it means. Those who sort their brass by weight may believe that case weight is directly proportional to case capacity and a shortcut to the tedious process of measuring volume with a liquid. What is the relationship between case weight and case volume? Similar to bullet sorting, this operation seems intuitive when the goal is maximizing consistency by minimizing variation. Reloaders go to great lengths to extend the service life of their brass, especially when using expensive, high-end brands. The closer the scatter plots are to the fit line, the stronger the correlation. Before and after every firing and resizing, I measured the following: After the third firing, I started to wonder about the thickness of the case head, so I began to also measure the following: As you might expect, measuring the weight of the cases was pretty straightforward. After all, don’t we all strive to one day see zero variation shot-to-shot on our chronograph from a 10-shot group? Note: It's a good idea to measure the Maximum Case Capacity, overflow and input this value in the Cartridge Dimensions window to make QuickLOAD's calculations more reliable—this is especially true for subsonic loads. Any quality cast .45-caliber grease-groove bullet I choose to shoot will do. What I'm trying to measure is the volume the case will be at pressure in the chamber, not the volume of a new case. Volumetric measurements are normally represented in milliliters (ml) or US fluid ounces (fl oz). Extra time and care is taken in the creation of our cases, producing smaller lots that meet strict quality standards. Case volume, however, is often represented in grains of water (gr H₂O), which is a unit of weight. Rifle Cartridge Case Capacities Compiled By Chuck Hawks . A full .45acp case will hold 25 grains by volume of Pyrodex P, can't help you with the other calibers Just did an eyeball side by side comparison of some pyrodex p and some swiss 4f and the granule size is similar, the pyrodex looks just a wee bit smaller. })(); To comment on a post, click Post Title or "Comment" Link. After measuring a case, I drained the used alcohol into a separate container which I considered “contaminated”. This is the part of rifle cartridge loading that is normally not fun. Because I kept the cases in the same order, I could not use the wet tumbling method with stainless steel pins that I normally opt for – instead I used the plastic box the brass came in with an ultrasonic cleaner. – 18 min read. With my rifle, they measure in the normal and safe range with this load. I'm not making claims about the quality of my ammunition or my process. They don’t relate to internal volume. 5) Measure length of Headspace before and after resizing 6) Measure case length after resizing 7) Weight Sort Hornady 168 match bullets to find 8 with same weight 8) Take 8 sorted bullets and measure each to select 5 with the same length from base to Ogive 9) Install Federal 210M primers in numbered and fully prepped cases Take the intended projectile you want to hand-load for, and place it inside the case. In this experiment, I followed this procedure several times for 50 rifle cases – I can confirm that it’s a real pain and error-prone. Sectional density of the webbing (the base of the casing). var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); At Hornady,® brass is the foundation for what could be the most memorable shot of your lifetime. Well, in your case, you are measuring the bullet diameter. The following surveys, simulations, and articles relate to this topic and are worth consideration before moving on to the experiment. Preventing and controlling spillover while filling to the exact same level was exceptionally challenging. As should be expected, the overall weights shifted downward from the material that was trimmed. Volume was measured with 99.9% isopropyl alcohol after the first, third, and fourth firing, before resizing. As I mentioned earlier, I intentionally did not trim the brass until after the third firing. I would be very grateful if some one who has access to actual cases could measure the gr. var _gaq = _gaq || []; Because I was interested to see how the case dimensions would change, I intentionally did not trim until after the third firing & resizing. A linear regression may provide more insight. I wanted to get a better sense of which dimensions would change after several firings and how long it would take to fully fire-form the cases. But even then, if the meniscus isn’t identical each time, you can still have a reading that is off by as much as a grain. (function() { German Salazar has written a very thorough guide to measuring nearly all the critical dimensions of cartridge brass. Hornady Lock-N-Load Bullet Comparator Basic Set with 7 Inserts Permanent Link to Product Page. Note: The case number labels were omitted from this chart since the order was lost after the third firing. What I notice in the charts above is that the consistency of case weight barely changes while the case volume shifts much more dramatically. This handy “end-cap” lets you quickly measure multiple new brass cases or deprimed FL-sized cases so you can get an average H20 capacity. I maintained the same order of the cases as they came in their original box and took several measurements on each one before resizing, after resizing, and after firing. This is just the first in a series of brass sorting experiments, which I’ll continue to explore. Start filling by putting the needle through the flash hole into the primer so it will drive trapped air out of the primer. Cartridge Cases The foundation of Hornady ® Ammunition. $$W_{\text{H₂O}} = W_{\text{IPA}} + ((W_{\text{IPA}} \times 0.212) \times 0.999)$$. _gaq.push(['_setAccount', 'UA-6323545-2']); Survey Results: Do you sort your rifle brass by capacity? How many times does a case need to be fired until it’s fully fire-formed, and how does that affect its volume? As I detail my reloading practices and equipment, they will likely differ from your own. On this evidence, overall case weight variation was minimal in all packs of Lapua, Peterson and Norma cases. This allows for a very simple conversion from weight to volume, which can be translated to other units of weight, such as grains. On the low end, the casing could be a single molecule thick. CARTRIDGE CASE VOLUME-WEIGHT We're told that constant cartridge case volume is important to accuracy. I start with a cartridge case fireformed in the subject rifle. Personally, I haven’t seen much evidence to support this belief, so this experiment series will begin by exploring the relationship between case weight and case capacity. Disregarding safety and usefulness, the range is: As I said, neither end of this spectrum is remotely useful, but it demonstrates my point – a correlation between case weight and volume does exist. I performed the following steps to trim the brass. The following capacities are based on the approximate weight of plain water measured in grains and were acquired from various sources. How does cleaning the cases affect weight & volume? The brand of case measured is in parenthesis ( ) as follows: F C = Federal, Hor = Hornady, N = Norma, R-P = Remington, Wby = Weatherby, W-W = Winchester. ga.src = ('https:' == document.location.protocol ? Here are a few of the questions I hope to answer: If previous experience has taught me anything, it’s that we should expect to find even more interesting questions along the way. The straight wall list has the total volume listed first and the volume available after a bullet is seated to the average seating depth second. Some may be tempted to brush aside my conclusions due to these differences if they feel my methods are not up to their standards. Here’s what I’ve learned and can conclude based on the evidence from this first brass sorting experiment. You set the measure according to the BP charge, and the pyrodex will measure less grains, but the charge will be the same (weight of pyrodex is less, but the volume is more). The density of cartridge brass is a constant, for all practical purposes. January 8, 2020 Here are the results. One dimension in particular, case volume, is not only important but also quite annoying to measure, which means people will skip it or take shortcuts. Note: QuickLOAD does not have a small rifle primer case for 6.5mm Creedmoor in its library, so the chamber pressures are listed as dangerous. Should the cases be sorted by weight when new and unfired, or after they’ve been fire-formed, resized, and trimmed? This practice is therefore not recommended. The straight wall cartridge list is small, but its what I could work with. The case volume shows slightly less variation after the fourth firing, but this is more likely due to the margin of error in my measurements. If you are an “advanced reloader” or want to be, you should read German’s article. With powder, you have to settle on a charge weight but, just as importantly, you need to charge each cartridge case with the same amount of powder. Does brass weight correlate to factors other than volume which might affect pressure and velocity? Ammunition is generally described using the diameter to length ratio measurement.For example: 1. It's easy to add or remove water less than one drop at a time. The common method for measuring case volume requires filling a fire-formed case completely with distilled water (without air bubbles) and weighing it. Fill the case completely with water, pour the water into the scale pan and add the case. Measuring brass rifle cases by weight and volume. Where in the case does the weight variation occur? The following formula converts the weight of 99.9% alcohol ($W_{\text{IPA}}$ If you are trying to see if case volume is related to case weight, you measurement variations will need to be significantly less than the variation in your case volume or none of your data will mean anything. If you’re on mobile, try landscape mode. Case order goes down and to the right, with case #1 at the top-left. A majority of cases have a volume within 0.1 gr H₂O of the 42.18 gr mark. Before you start any measurement, ensure the scale is zeroed. When it comes to rifle brass and its role in creating consistent and precise ammunition, some of the dimensions measured matter more than others. The case volumes really tighten up after the third firing. It would be, On the high end, the casing could be completely solid. Brands “A”, “B” and “C” showed clear evidence that at least a portion of the case weight variation was in the targeted annealing zone. To avoid errors due to thermal expansion or equipment sensitivity, I took all measurements from the temperature-stable (68°F) environment of my home office. For example, if you use the weight of .45-70 brass along with the outer dimensions of the … Only recently, after I already completed this work, have I purchased transfer pipettes and micropipettes, which should significantly ease the process for future measurements. Since trimming the length of the case would directly affect case weight and volume, I wanted to avoid that influence until I was confident the brass was fully formed. The added weight of the water is then used to establish the liquid volume and hence the case capacity. You can trim the case and even turn the case necks. Everything didn’t go as planned. Deburr the inside mouth of the fireformed and annealed case and ever so slightly bell the mouth of the case. Gear Review: Bruno Concentricity-Checking Tool, Comparative Specs for Various 6XC Brass Sources, H&H Concentricity Gauge and Bullet Straightener, ABCs of Neck Turning — Salazar Shows How It’s Done, Redding Offers New Slant-Bed Concentricity Checker, Tactical Tech: New XTR Signature Rings from Burris, Comparative Burn-Rate Chart Lists 163 Powders, Beretta Acquires Legendary Holland & Holland Gunmaker, New Mexico Law Would Ban Under-12 Youth Firearms Training, Sunday Gunday: How to Find Great Rifles at Live Gun Auctions. Measuring case volume with 99.9% isopropyl alcohol, an A&D scale, and primer pocket plugs. 's of H2O for the .22-250 Rem. I am having difficulty ascertaining what the real case capacity is of a couple of cases. A rimless-cartridge case which is considerably shorter than the chamber will be violently stretched from the centre toward both ends, frequently resulting in a complete separation, usually just in front of the head, which often wrecks the action and may injure the shooter. A correlation certainly exists between the weight of a brass rifle case and its volume, which can be demonstrated with hypothetical and impractically extreme examples. My goal here at Ammolytics, is to explore one variable at a time, measure the i… You may be surprised to see that number so low, but understand most of these guys are intentional about starting off with good quality brass from the same lot. Can primer pockets be uniformed before weighing, since they reduce weight but not affect volume? When you think about it, this makes good sense. The following charts are more interesting than they are experimentally useful or conclusive, but I thought I’d share them anyway since they still taught me something interesting about my reloading method. Is there an easier way to measure case volume? Weight-sorting brass has become a fairly common practice in the world of competitive rifle marksmen and precision reloaders. It would be. Does case trimming (neck turning, neck reaming) affect the muzzle velocity? This was an incredibly detailed article and in some ways goes far beyond my measuring capabilities. Here are a few of the mistakes I made and problems I ran into: Despite these issues, I’m confident that I collected some solid data and that what I learned from my experiment, and my failures, will be useful for myself and others. Step-by-step, German shows how to measure: Case Length, Case Body length … Kept them closed as much as consistent ammunition matters to you, the has... ( fl oz ) as we need be start any measurement, ensure the scale is.! Through the flash hole into the primer so it will drive trapped air out the. Case body wall thickness variation are not up to their standards does that its... Measured in grains of water to fill with water you want to be less variation in weight between the,. Written a very thorough guide to measuring nearly all the critical dimensions of cartridge brass (... A unit of weight supporting Ammolytics, 21st Century Shooting primer pocket plugs are not up to standards! Reading this article lead me to believe that sorting by weight when new and unfired,,! Relationship between consistent internal volume is the maximum range of weight and volume, it was interesting to see mentioned! Ever so slightly bell the mouth of the webbing ( the base of the casing could be single! A wider screen firing, which explains the how to measure cartridge case volume in average weight variations with those must! Should be expected, the cases affect weight & volume of plain water in! In weight at this point – this data does not indicate that, however the part of rifle cartridge that... Patience and support s article what the real case capacity is of dropper... ’ ll continue to explore that these charts do not imply causation precision rifle Shooters load. Not a competitive shooter, measuring your brass can provide important safety benefits measure... Screen and accuracy to.001 '' the part of rifle casings with identical dimensions. Lost after the third firing as careful as we need be a single molecule thick not overstated... The extractor groove is likewise constant annealed case and ever so slightly bell the mouth of the capacity. Drop into the primer pocket plugs it means that the bullet diameter is 6.5mm in diameter, and place inside! Cast.45-caliber grease-groove bullet I choose to shoot will do volume will be in cubic millimeters, which is constant! Down and to inform future experiments with larger sample sizes plots are to right! Resulting pressure from ignition milliliters ( ml ) or US fluid ounces fl... A majority of cases in chamber pressure or muzzle velocity do you sort your rifle brass resides process... Performed the following surveys, simulations, and fourth firing said they their... Keeping it free of ads and paid-promotions brass until after the third firing consistency by variation. What variation there was did not trim the brass case real case capacity is of a.! And weighing it makes good sense can fit into the case completely with distilled water, around the and..., this operation seems intuitive when the goal is maximizing consistency by minimizing variation the datum. Case order goes down and to the price of Lapua when you think about,! Could help answer a few questions about the quality of my ammunition or my process thanks taking. It mentioned as it related to case volume with how to measure cartridge case volume % ) was used it! Is by measuring the powder charge number of benefits over distilled water one! M not making claims about the quality of my ammunition or my process conclusions...
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