Shotgun proof pressures. RandyWakeman · Registered.
- Shotgun proof pressures By far the most common gun failure arises from shooters confusing the different sizes of shotgun shells. To put things into perspective, we are talking about a 2500 psi maximum pressure increase. com) DamascusKnowledge www. Date marks. Just because a shotgun was proofed to a certain level does not at all mean it could not be proofed to a higher level. Total pressure is the area swept by the entirety of the pressure curve which evolves between ignition and muzzle exit. This is of There are two Proof shotgun pressures in use by the CIP Proof Houses, 850 Bar and 1200 Bar, but these are not stamped on the gun, just the chamber length that is appropriate. so these work out like so SAAMI standard service pressure for a 2 3/4 inch or a 3 inch 12ga shell is 11,500 psi. MAP is simply maximum average pressure that a shotgun can withstand continuously and still last for the entirety of its engineered service life. Gregory J. The maximum average cartridge Shotshell pressures seem to be a worrisome area for many shotgunners, especially reloaders. " By and large, shotguns today are FAR, FAR stronger than they need to be. Tom Armbrust tried to burst a Winchester Super X-1 barrel years ago and the pressures were well into the 50,000 PSI range(yes I have my figures correct), when the barrel finely bulged and cracked. And THAT is why the SAAMI standards are for a "maximum average" pressure, well below the proof loads. 1989-> “DA” and the last numbers of the year. London. 5kpsi +/- 900-4600psi, or uber max of 25. A service pressure of 3 tons per sq. Arms previously proven and bearing apparently valid proof marks are deemed out of proof if any pressure bearing component of the small arm has been materially weakened in substance or strength. At least that's what I've read. If inserted into a 12-gauge gun, a 20-gauge Proof is a very old procedure, and was established long before any scientific basis or metalurgical knowledge could really back its validity. The proof act assumes that if a barrel can pass proof, it is strong enough. Pressures that actually damage an unobstructed bore in a modern shotgun, will be well past proof pressures. 70 (70%) and rounding DOWN to the nearest multiple of 100 psi. (1220 fps) The Proof House did not publish pressures but other period published pressures How about so-called low-pressure loads? To many shotgunners this is some undefined but desirable pressure level assumed to automatically produce the dubious benefits detailed but rebutted above. The proof mark of the Eibar proof house will always be in front of the pressure mark. Come join the discussion about optics, hunting, Turkish Shotgun Proof Pressures. The initial London date stamp from 1972 also included the letter “H”, but that was 12g 65mm - 70mm = 2 1/2" - 2 3/4" "standard proof" lead or steel (limited to no larger than 3. 710-. The proof pressure is not always stamped on the barrel, The pressure curves were measured in a 12 Ga Shotgun firing 1 1/8 Oz of No 6 Shot, all at 1220 ft/sec muzzle velocity (except for the BP Proof curve). ANSI/SAAMI Shotgun Pressure Specifications (Maximum Average Pressure in PSI) All Piezo measurements unless specified) Cartridge Maximum Average pressure 10 gauge 11,000 (all) Proof loads, other than being in a clear hull with 'Proof' written on the side, do not show any signs of high pressure. In fact, I would not shoot it with any ammo. I assume the Turkish ammo makers are perfectly capable of producing loads to proof pressures. Miroku of Japan, who make the traditionally-styled break-action Brownings, have adopted Browning’s date coding system in their serial numbers. I take it the gun manufacturer has long since gone out of business? The Belgium proof house should not have and maybe you can contact them with the barrel marks unless we have some Belgium readers that can answer your questions. , that makes CIP proof pressure is 1080 bars (15,660 psi). Or look at it like this that 1200 BAR marking is a 130% proof load pass stamp. For 2-3/4" 12 Gauge (as an example) if the SAAMI maximum average pressure (MAP) is listed as 11,500 PSI, then Depending on the powder used, velocity seems to follow pressure in shotgun shell loadings fairly closely (not a hard and fast rule by any means). in. (think international proofing organization) which now dictate the pressures various firearms need to withstand to make proof. They worry that if they shoot excessive pressure loads that their shotgun could well “blow up. Joined Oct 13, 2022 · 5,146 Posts #61 Some Turkish makers say "Proof" and others "Pressure" testing, and if a manufacturer fo GUNS uses a SAAMI proof loads ( a big "if"), then the gun will be proofed by a lot of no less than 10-shots of ammo loaded to a maximum proof pressure of 20. You might see if you can find any collector's of the shotgun and perhaps they would know what shells are safe to fire. “DA” stands for “DeActivaded”. I have to stress that these are Proof pressures, not service pressures which are (I Reference & Proof Ammunition Information. So much for low pressure loads for older shotguns!!!! At shotgun pressures, if 1000 is added to LUP it will equal the PSI rating. I don't always venture out into the sub-freezing darkness, but when I do, it is hunting season, and I carry a Browning. I. Joined Sep 9, 2006 · 32,813 Posts #41 · Jul 7, 2023. A simple primer change can change pressures by 3000 PSI. It lists over 30 specific shotgun calibers along with “Although the Maximum Mean Pressures for service loads for standard proof (850 BAR) guns are 740 BAR, CIP regulated cartridge manufacturers typically work to lower If a manufacturer uses a SAAMI proof loads, then the gun will be proofed by a lot of no less than 10 shots of ammo loaded to a maximum proof pressure of 20,500 psi +/- 900 - With shotshell chambers varying in length and diameter, exact pressure cannot be predicted. My Sarasqueta from 1970 is stamped at 1100kgs/cm^2 which is over 15,000 psi. The SAAMI standard proof pressure is about 19,000 psi, similar to CIP Superior These numbers SHOULD apply to guns proved under the 1925 rules, which were stamped only with chamber length and shot charge. 1950 -> Final black Powder proof . fps 1,300) transducer psi Service pressure 740 BAR = 10,733 psi Maximum statistical individual pressure 850 BAR = 12,328 psi Standard proof 930 BAR = 13,489 psi 12g 76 mm = 3" lead "High performance/superior proof" transducer pressure British guns bearing Birmingham proofing have markings including, for example, 3 1/4T, 2 3/4" and 1 , 1 1/8 or even 1 1/4 oz. Same with the Spanish proofs. However, one gunsmith I spoke to said this number is a guide that will be safe in any 12 gauge shotgun, but that modern guns from Beretta and Browning should be able to handle more pressure (14,000 psi). shot. no pressure testing is required. 25 = mean proof. NOTE: In the event the difference between the calculated Minimum and Maximum Average Proof Pressures is less than 1,500 psi, the Maximum Average Proof Pressure shall be positioned 1,500 psi above the Minimum Average Proof Pressure value. I have to stress that these are Proof pressures, not service pressures which are (I British guns bearing Birmingham proofing have markings including, for example, 3 1/4T, 2 3/4" and 1 , 1 1/8 or even 1 1/4 oz. Proofing is an electro-mechanical process of testing barrels to be sure that they will withstand normal shooting for hunting or competition. ” To optimize your shotgun’s performance in these conditions, you need specially constructed loads perhaps upgrading to a medium burn rate powder. P. But these are generally mild excess pressure situations, not gigantic ones involving double and triple charges of powder. (4) Notice that all the shell pressures are below proof load pressures. From my perspective, @RandyWakeman has clearly and concisely presented us with the definitive (and also simple) answer to determining if any given reload is potentially in 'nominal' compliance with SAAMI practice right here (I. This misunderstanding stems from the failure of those discussing or writing about the subject to differentiate between high versus excessive pressures The CIP standard for 850 BAR is “Maximal Statistical Individual Pressure” = 12,328 PSI for a “Maximal Average (Service) Pressure” of 740 BAR = 10,733 PSI, and “Mean Proof Pressure” of 960 BAR = 13,924 PSI. However, keep in mind that mildly excessive reload pressures are continuously stressing the gun and contribute to high recoil The Liege proof house pressures were expressed as Kg/cm2 after 1924; British as (Long) Tons by LUP (though not marked on the barrel flats until after 1954). 5" 12 ga. Europe manufactures shotguns and shells to CIP ("Commission internationale permanente pour l'épreuve des armes à feu portatives" - "Permanent International Commission for the Proof of Small Arms") specifications. Proof loads will produce pressures well in excess of whatever an extra 4 grains of powder will exhibit. Shotgun max pressures are in the 11,500 to 12,500 PSI range, and as such do not produce pressure signs per-sae. into a 3. It just means that it hasn't been, so it is unknown. Proof loads are to assure that they are safe with normal loads. Joined Oct 13, 2022 · 5,146 Posts #61 · Sep 5, 2023. Check with the individual manufacturer for their policies. From Tom Roster: "Where excessive shotshell pressures generally occur is in improperly put together reloads. You will always be in the lower third of 700X's pressure range when using it for shotgun reloads, whether you statistical individual pressure, 930bar mean Proof pressure. That's all you've got now Randy, and you are Turkish Shotgun Proof Pressures | Shotgun Forum (shotgunworld. I'd guess that continual use of the hi-performance loads at 1050 bar will cause a gun proofed at 1120 bar to shoot loose sooner rather than later. Proof pressure according to CIP. The SAAMI proof load for this shotshell is 19,000 PSI to 20,500 PSI, a bit more than 20%. Joined Sep 9, 2006 · 32,851 Posts #33 If a shotgun was built like every other gun, a 12-gauge would only have a "safety factor", which is it's proof testing, to about 14-15,000psi. SAAMI Product Codes and Supplier Information 12g 65mm - 70mm = 2 1/2" - 2 3/4" "standard proof" lead or steel (limited to no larger than 3. has no government proof house. Turkish Shotgun Proof Pressures. So, it is never wise or safe - and nothing positive is ever accomplished - by firing modestly excessive pressure loads in any shotgun. , you need all the help you can get. If you Google "CIP Shotgun Proof Pressures" you should get a list of articles that explain things in more detail. A point which identifies the brief moment of greatest pressure witnessed along the Y Axis. Before buying an old English or European shotgun you must learn the proofmarks of the country of origin, determine if they are appropriate to the loads you want to shoot and you must absolutely determine that the gun is still in proof. Why are Shotgun Proof Marks Important? Shotgun proof marks hold great importance for both gun manufacturers and firearm owners. 5" 12 gauge must be undamaged by a shell of 20,000psi. A non-3. guarantees that U. 1950 -> Indicates test firing for aim and pattern. Silver_Is_Money · Registered. MAP x 1. with 1 1/4 oz. Come join the discussion about optics, The proof act does not cover wall thickness, though for most practical purposes, wall thickness is more important than bore size (as long as the gun is still in proof). Proof Pressures. Rem STS hulls, Cheddite primers, CB 1100-12 wads, 1 oz. But this powder charge doubling potential is If you have a standard-proof gun with NO Fleur-di-lis proof stamp: CIP maintains that it will not be damaged by shells firing steel shot with a velocity of no more than 1,300 fps, AND a shot size no larger than U. CIP maximum service pressures are 75% of proof. (BAR) = 13,920 psi proof pressure= 10,730 psi service pressure (SAAMI) A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns brands. " A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns brands. 417244 of an inch. S. It seems to me that gun manufacturers would publish a max pressure value (proof value) for their products but I can't find it if they do. For 12 bore shotguns there are two levels of proof, Standard at 850 Bar minimum for chamber lengths up to 70mm and Superior or Magnum at 1200 Bar minimum for all chamber lengths above 70mm. Lefteris. BOTTOM LINE: ANY 850 BAR (proof) = 650 BAR service or 3 TON service gun should be fine at pressures under 8500 psi, or 3 1/4 tons less than 9,500 psi. The Proof Master and colleagues also work with the CIP to set international standards for proof, and they investigate serious pressure-related failures of guns to try to improve gun safety. I'm sure someone will correct me if I'm wrong. 5" 10 ga. 25 mm and max. I would need a shotgun 12/76 for hunting, and I like old tools. On this site - moocher said: Don't know about 28 ga. The CIP High Performance 3" and 3 1/2" (Magnum & Steel) is for a Service Pressure of 1050 BAR = 15,229 PSI, and Mean Proof Pressure of 1320 BAR = 19,145 PSI. The next sequence of digits is the manufacturer’s serial number, and the last pair of Hello, SAMMI lists the maximum safe chamber pressure of 12 gauge shotguns with a 3" chamber at 11,000 psi. That's about 9000 psi max average working pressure. fps 1,300) transducer psi Service pressure 740 BAR = 10,733 psi Maximum statistical individual pressure 850 BAR = 12,328 psi Standard proof 930 BAR = 13,489 psi 12g 76 mm = 3" lead "High performance/superior proof" transducer pressure High pressure takes on an element of perceived danger, because many shotgunners have been taught that so-called high pressures can cause shotgun barrels to “blow up,” bulge or split. Save Share Reply Quote Like. Second, Proof Load shells do not exhibit, in any way, shape or form, signs of high pressure. Judging by the stamps it was proofed in Suhl in February 1947 S/N 123456. lead shot. But that doesn't mean they are safe for "extended use" of these proof loads. However, if unsure whether your ammunition is High performance Steel, please consult the manufacturer. , as quoted above). I have no knowledge of Swedish proof regulations, but many Husqvarna were made for export. 4 KPSI. And most modern shotgun barrels will approach or exceed 50,000 PSI before they fail. When I discussed pressures with Tom Armbrust he recomended staying at about 65% of proof pressure, about European (CIP) proof pressure of 850 kg per sq. Help! Bob "If you tell the truth you don't have to remember anything. The SAAMI max. I reload for sporting clays, using a MEC progressive, 12 ga. 12 gauge HP pressure specifications are 1050bar MAP, 1200bar max statistical individual pressure, 1320bar mean Proof pressure. BASC, the British Association for Shooting and Conservation, has published a paper that states that guns proofed to 3 1/4 tonnes are safe to shoot standard CIP 12ga loads. For magazine shotguns with a restricted magazine capability. 14 countries in Europe have adopted standards laid out by C. If unsure whether your shotgun is suitable for use with High Performance Steel ammunition please contact a competent gun dealer, gunsmith or the British Proof Authority for advice, this may involve the submission of your shotgun for inspection. Proofing firearms began hundreds of years ago in Europe (1637 in the UK) and continues to be conducted as described above. 7 Tons would be in the 20,000 PSI range which compares to SAAMI's current proof pressures of 19,000 to 20,500 PSI. I am not a ballistics engineer but I assume when you try to turn a 3. 1950 -> Max working pressure Mean PROOF Pressure 960 BAR = 13,924 psi 12g 3” & 3 1/2” “High performance/Superior Proof” lead or steel Maximum Average (Service) Pressure 1050 BAR = 15,229 psi A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns brands. 1 4 of 5 Go to page. Birmingham. #5, AND a momentum of no more than 12 Newton seconds AND a chamber pressure of no more than 11,500 psi. There are defined internal bore size (4) Notice that all the shell pressures are below proof load pressures. Considerably less than that of a proof load. Some proof marks also indicate that the gun has been subjected to a specific level of pressure testing, ensuring it can handle the expected pressures generated by firing ammunition. = 8,938 psi service pressure (SAAMI) MAX 1050 BAR mark means that those shell comform to CIP standards for magnum ammunition in that they will not exceed maximum service pressure of 1050 BAR. The second two digits identify the type of gun, and 03 indicates a shotgun. RandyWakeman · Registered. ” They’ve heard that from To help you visualise the proof pressures in a 12 gauge shotgun, the standard proof pressure of 930 bar is roughly the equivalent weight of an early 1970’s Porchse 911 on 1cm of your barrel. I presume that after each barrel is stressed via firing 1550 BAR (22,481PSI) proof test loads in it, it is subsequently Magnaflux inspected For magazine shotguns with a restricted magazine capability. I have not found information about these marks ( picture 2 ), and I would need to know if this shotgun can handle pressure and/or can shoot steel shots. 740) were proved for a maximum service load of 3 1/4 Dram Eq. One of the commonest problems in old guns (particularly big bores) is the degree of pitting not allowing the viewer to "throw a shadow" down the barrel. etc. for 3" shells is 11,500 psi Yildiz guns The U. " Click to expand And yet, no 3" or Before one start with the technical details, one must understand somewhat of the history of the way in which shotguns have been proofed in modern times. He needs to do Most modern shotgun barrels are actually proof tested at or about 20,000 PSI. Guns proofed for "high performance steel" under CIP standards have a higher proof pressure than SAAMI proof. Italy and Spain both build date codes in the proof information stamped on their guns. Hot primers are more likely to My quick research says not to worry about it since modern shotguns are engineered to handle significantly more pressure than the SAMMI spec. It lists over 30 specific shotgun calibers along with Modern 12g and 16g 2 3/4” and 3” SAAMI Recommended Proof Pressures If a manufacturer uses a SAAMI proof loads, then the gun will be proofed by a lot of no less than 10 shots of ammo loaded to a maximum proof The larger the pressure vessel, the lower the range chamber pressures; the smaller the pressure vessel, the higher the range of chamber pressures. B16. guns are actually proof tested at 18-20,000 PSI and will almost all withstand around 45-50,000 PSI before they fail. Jump to Latest 41 - 60 of 84 Posts. Note: The purchase of Reference and Proof Ammunition may be limited to individuals and businesses with legitimate need and proper controls in place. Proof pressures will not destroy the barrel or receiver of a properly made firearm. The net result of this is every time I take the first shot at a mule, the actual peak chamber pressure attained by the cartridge fired may exceed 120,000 PSI. Come join the discussion about optics, hunting, gunsmithing, styles, reviews, accessories, classifieds, and more! Shotgun markings explained. This chamber is larger than the . Under the BRITISH 1896 Rules of Proof Pressures 12g 2 1/2” and 2 5/8” chambers (bore . However, the CIP hi-performance shells are getting close to the CIP standard proof pressures. CIP proof of 850 bar does not mean that it could not be proofed to higher standards, like the high-performance steel CIP levels. Year denotes the year of change. Westberg British Proof Houses from 1954 to 1984 when they went over to the PROOF pressure in Kgs and then 1989 they went over to PROOF pressure in Bar. cm. Shotgun World General Forums. Lengthen the chamber on a shotgun in the UK (and other countries) is illegal unless the gun is reproofed. 15 = max statistical individual pressure MAP x 1. or or. The English employ the long ton (about 2200 lbs, I believe) but I still cannot make that add up to, for example, 8000-10000 psi chamber pressures of some light game loads for a 12, 16 or 20 g shotgun. The proof pressure test is a once only test applied at the time of proof. 1950 -> Final nitro/smokless proof. It requires large amounts of shot and powder to get to proof, let alone to the level required to exhibit true pressure signs. Go. Chamber mods "take the gun out of proof. but the modern 12 ga. The diamond with the 12M over a C indicates that the gun has, in fact, a 12mm chambered, choked, shotgun barrel and not a . Hi Frank, there is a discussion on this subject over on the Upland Journal BBS (Under the Titles of BSA Shotguns and Chamber Pressures). Jump to Latest A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns brands. If it is strong enough, the walls are ,by definition, thick enough. 1 KPSI; and, will be similarly a MINIMUM average proof pressure of 19 KPSI +/- 900 - 4600psi for an absolute minimum proof of 14. Reading the proof pressures are a little confusing. firearms are proved in house. This document provides specifications for calibers of smoothbore center fire shotguns, including nominal case lengths and diameters, chamber lengths, and maximum pressure values. I have been using Alliant Clay Dot 17. I dropped the load several grains and worked up until I got a recipe that was nudging against the acceptable pressure ceiling. General Shotgun Discussions As observed Turkey is not a CIP member country and proof (pressure) testing is voluntary, just like the U. Tuula and Izhevsk. The "blue pill" loads to proof test US barrels/actions are also overloads of a similar nature. These shell are to be fired from a magnum proof shotgun which 1370 BAR per CIP standards. 5" guns and light 2. What you find stamped on the gun is the allowable working pressure, not the proof pressure. The pressure on European guns is the proof pressure and the working pressure is but 70% of that. Jump to Latest 61 - 80 of 84 Posts. On a national level a lot of countries have used different proof methods, but at the bottom line - the simple fact is There are two Proof shotgun pressures in use by the CIP Proof Houses, 850 Bar and 1200 Bar, but these are not stamped on the gun, just the chamber length that is appropriate. My friends at Accurate Powders / Western Powders inform me they have seen To get a handle on high versus excessive pressure, let's look at 12-gauge 2¾" loads. The vigorous personal injury industry in the U. A proof pressure is considered a dangerously high, over-pressure load never to be approached, much less exceeded. 5 grains for a 1200 fps shell producing 9940 PSI. Frank. The CIP 740 BAR loads are for the CIP 900 bar proofed guns in wide use in Europe, mainly 2. all of these specifications are calculated from the MAP. 410 and would measure . The barrel never actually burst. 1950 -> Final proof with nitro powder and test shooting or . But I would need a shotgun with a gun barrel that can use steel shots, not led shots. 0 grains but could no longer get that powder, so I switched to Alliant Extralite, where the recipe calls for the same components with 16. In my opinion, I would never shoot any modern smokless ammo in the gun. The chance that you can, by accident build proof pressure level shells is extremely small. Second, the proof pressure mark is placed twice on the flats, one proof pressure mark for each barrel. Date The proof pressure test is a once only test applied at the time of proof. All about serial numbers and proof marks on guns from Italy, Spain and Japan and what you need to know when buying (for instance, 16 is AYA, and 13 is Lanber). The maximum average pressure (MAP) permitted by SAAMI for 12-gauge 2¾" service Proof pressures will not destroy the barrel or receiver of a properly made firearm. All the best! Greg . Translated it reads "This shotgun has been proofed with four equal firings through each barrel with a pressure of 1100 kg/cm^2 (15,645 psi) at 17mm 1370 BAR, well over 19,000psi. "The CIP service pressure of 650 BAR and proof pressure of 850 BAR is (expressed in lead) crusher values; CIP standard 12ga proof is something like 10,700psi. Drew Hause said: There IS however solid proof of higher pressures being GOOD from a reliability and clean-burning standpoint. You find it interesting. Whatever the young man might have done with his reloads didn't create the issue that you see on that spent hull/primer. Over time powder has evolved and measurement methods and units has changed. 75" ones. 410. 5. Come If a manufacturer uses a SAAMI proof loads, then the gun will be proofed by a lot of no less than 10 shots of ammo loaded to a maximum proof pressure of 20,500 psi +/- 900 - 4600 psi, or uber max of 25,100 PSI; and, will be similarly a MINIMUM average proof pressure of 19,000 PSI +/- 900 - 4600 psi for an absolute minimum proof of 14,400 PSI. You may also want to consider using heavier loads and new hulls for stronger crimps. They didn't specify the barrel type used but it was almost certainly some Proof testing isn't required in America because there is more profit in paying off those who receive a defective product than insisting each product is tested to the highest 52,000 PSI (or higher) peak chamber pressure where modern shotgun barrels will almost assuredly come apart. We had the Remington class-action suit (the Garza suit), etc. E. Proof pressure is about 50% higher. You can see how I've stacked the deck. It involves firing super-hot, high-pressure The rules were changed in the mid 90s and the pressures are now as follows: Magnum proof- the shotgun fires two proof loads from each barrel producing 1370 bars, about equal to kilograms per square centimeter and Mean PROOF Pressure 930 BAR = 13,489 psi 12g “High performance/Superior Proof” (and 3” & 3 1/2”) Maximum Average (Service) Pressure 1050 BAR = 15,229 psi; Maximum statistical individual pressure 1200 BAR = 17,405 psi A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns Temporary black powder proof . Lot Mean (MPLM) service pressure by 1. Only those unwilling/unable to answer simple questions (what does that 1550 BAR mean?) resort to ad hominem attacks. 1 3 of 5 Go to page. Thus, a 2 1/2" chambered gun, 1925 rules of proof, would be equivalent to 3 tons; a 2 3/4" chambered gun to 3 1/4 tons. Still, this number is much lower than what is called “proof pressure. In addition to chamber pressure, CIP sets limits on velocity, momentum, choke constriction, shot size, and other things. Save Share A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns brands. The service pressure is the pressure the gun withstands throughout its life. Frank Just because a shotgun is proofed to the std. I just got a Sauer VIII shotgun. Come join the discussion about optics, hunting, gunsmithing, styles, reviews, accessories It is supposed to be market the right flat of the barrel, gmos will follow the weight marking. Peak pressure is but a single point along the infinite number of points progressing along the X Axis timeline of the total pressure curve. Only show this user. There is also the unscientific and never-tested belief that pressure levels less than 7,000 psi automatically make loads OK to fire in old shotguns. uwkjqr jlh vww mbcoc wso asehj slei flqijh bzzgtb djzal