This means that when firing a .308 round in a 7.62 chamber, the .308 brass will stretch beyond its intended elastic range. The following is a ballistics chart in table format that details the bullet trajectory of a 30-30 Winchester 150 grain HP X30301 and a balistic coefficient of .218. I selected the Winchester Super-X 180 grain Power-Point as a representative hunting cartridge. This calculator will produce a ballistic trajectory chart that shows the bullet drop, bullet energy, windage, and velocity. The vast majority of rifles, carbines, and pistols chambered in .308 Winchester can safely sling 7.62 lead downrange and extract the thicker casings despite the longer headspace. This project, and all of its results, is only our fault. This resulted in a velocity loss of 106 feet/second. Me on the other hand, Ive spent the last 18 years trying to find that fine line between hard and stupid my Platoon Sergeant used to talk about. Troubleshooting seized ejectors. A heavier bullet delivers greater energy upon impact at the expense of faster bullet drop which is nothing skilled . My 16.5 308 Winchester (above) is a fun little rifle. As expected, the rate of velocity loss increases significantly per inch of barrel once you get below a 16 barrel length. A. This weight is more appropriate for whitetail deer and other small-medium sized game. Stay safe, yall! Contrary to the popular urban legend, 7.62 NATO casings do indeed have thicker walls than .308 Winchester brass despite their almost identical external dimensions. While U.S. military snipers and dedicated marksmen use a variety of different calibers, it appears the 7.6251 is here to stay for the foreseeable future. My lathe is a two hour round trip to the range. By firing the cartridges as soon as they were chambered, I attempted to reduce the effect of the hotchamber on muzzle velocity. However, testing indicates it may not be as much as initially thought. My calculations assume a 1.75 sight over bore height. Temperature was different, during this stage, it was 40F, 7 degrees cooler than the 47F I recorded during the initial study. 0. 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; I shook vigorously from head to toe. While the external dimensions of both 7.6251 and .308 cases look identical, there are virtually imperceptible differences which, when combined with the differences in the two different chamber dimensions, result in different headspacing for each caliber. of this rather nutty project. Try these too.. Powder burn rates can also make a difference. My data showed an average change of 27 ft/sec per inch of barrel. .277 Fury has a -41 inch drop at 500 yards . Thanks for the kinds words about the 308 and 300 Win barrel length posts. Mag. I had 100% extraction during the course of this experiment. I used my iPhone to record a couple shots being fired in slow motion. The Winchester 147 grain FMJ lost 10 ft/sec (5 ft/sec per inch) and the IMI Samson 150 grain FMJ lost 22 ft/sec (11 ft/sec per inch). I bought a quart. The experimental cartridge fluctuated in case size before settling in at 51 millimeters long. Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. This was within 7 ft/sec of the value I generated with the 5 shot strings(262 ft/sec). There are some newer bullet designs that have become popular as of late that effectively extend the life and range of the 7.62x51mm NATO/308 Winchester even further. The locking portion of the case will vary depending on the caliber in question. Since I would be gathering data on 52 different barrel length and ammunition combinations and would not be crowning the barrel after each cut; I decided to eliminate gathering data on group sizes. Looking for a two-minute summary of the differences between 7.62x51mm NATO and .308 Winchester? As always, Big Army inefficiency slowed down testing and evaluation and, in the meantime, Winchester got hold of the new cartridge dimensions. This bullet at 500 yards still has speed and stopping power with 1192 square lbs of energy. This chart shows velocity changes for all four ammo varieties: Summary of Findings: The average velocity loss per inch, for all four ammo types combined, was 22.7 FPS. Did it really hurt to shoot a short 308 pistol? var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; The heavier weight and newer designed 175gr Sierra . In addition to riding on the back of the 7.62 NATOs short-lived military career, the .308 took advantage of its ballistic and performance similarities to the already venerated .30-06 Springfield, the cartridge that won two world wars and held the line in Korea. Share the post ".308 Win Barrel Cut-Down Test: Velocity vs. Barrel Length", Tags: .308 Win, 7.62x51 cut-down test, Barrel, Rifleshooter.com, Saw, Velocity. Ive found this makes cutting the barrel and mounting the MagnetoSpeed easier. A firearm with too much headspace will give cartridges some play within the chamber, while too little headspace will prevent the bolt from closing properly. Headspace was measured at 1.633+ (.003 over minimum). .308 Winchester (7.62mm NATO), The Army wanted a new rifle caliber with performance comparable to the proven .30-06 but with a shorter overall length, a new wonder cartridge. All content Copyright 1998-2018 Rifleshooter.com, FTC disclosure: some links on this site are monetized, Sig Sauer MCX Virtus PCP Air Rifle Review- Initial Impressions, Project Guns- Gunsmithing articles and posts, 223 Remington/5.56 NATO, velocity versus barrel length: A man, his chop box and his friends rifle. the cylinder gap. Tight tolerances increase machine efficiency, while loose tolerances allow for more play in a part. With the .30 caliber bullet diameter being translated as 7.62 millimeters, the new 7.62x51mm cartridge was born. Red Oak, White, or Chestnut for Deer Herd? No guessing, no models, no arbitrary numbers. This means throwing .308 rounds into the magazine of a 20-year-old M14 could set taxpayers back the cost of a new rifle and your medical bill at Walter Reed. The latter has nearly twice the propellant, and is therefore better able to fell very distant game. Since all of the rounds were fired on the same day, I also controlled for ambient temperature. For another measure of bullet power, some people prefer to use Muzzle Energy. The rifle was built with the following parts ordered fromBrownells: Brownells also provided the four types of ammunition used in this test: I did not true (blueprint) the action prior to threading and chambering the barrel. Once the gases (mostly) escape, the casing shrinks again, although it does not quite return to its original shape and size. NOTE: Many shooting newbies may see the number combination 7.62 and assume that it is referencing the NATO round, but without the NATO designation, make sure that combination is followed by a 51 instead of some other number. The cuts were made in one-inch intervals with a rotary saw. Fear not. The .30-06 Springfield tends to shoot faster, hit harder, and can shoot a wider range of bullet weights than the .308 Winchester. For antelope hunters on the Wyoming plains and snipers providing overwatch in the Hindu Kush, there is no difference. The barrel was cut off using a cold saw. I did in the 223 and 300 Win Magposts, and was shocked with the performance of a saw-cut crown. The short answers to these questions are yes and maybe. Barrel length, Barrel length and velocity, Cartridge Selection photo link: http://rifleshooter.com/wp-content/uploads/2015/01/custom-16.5-rem-700-308.jpg. Do a search on the internet for 7.6251, and you will get results for 7.62 NATO, .308 Winchester, and multiple variants thereof. Wind Direction is: 3.0 o'clock and a Wind Velocity of: 10.0 Miles per hour. ALL Bulletin content is copyrighted, 2023 AccurateShooter.com. Temperature was 47 F.. The U.S. militarys 7.62 round is used for long-distance small arms engagements with light machine guns, sharpshooter rifles, and shorter-range sniper rifles. JHP: Cor Bon 225 gr. Read on, and it will all make sense. Velocity loss per inch of barrel was .6 ft/sec away (22.8 ft/sec)from the value calculated with 5 shot strings. Until then, stay safe. While this may sound contradictory, it isnt. Compare that to a 5.56 Ball M193 round's 55 grain bullet, which delivers a . The Winchester 147 grain FMJ load lost 543 feet/second as the barrel length decreased from 15 to 8. Cartridge Type: RifleHeight: 2.015"Width: 0.473"Average FPS: 2681Average Energy: 2617Average Gr: 164Recoil: 1.95Power Rank: 4.4 of 20. 30-30 Ballistics Chart & Coefficient. Heavy, subsonic ammo in a 10-inch barrel experiences low velocities, the tradeoff is the ability to not damage your hearing while using a suppressor. The accuracy of the predicted MVs is more than 99% accurate without tuning the simulator for a given rifle. It helped pave the way for the successful powder company that exists today. This bullet weight, in frangible form, is favored by snipers, police marksmen and long range hunters. I think if you tinkered enough you could do 1,000, however I dont think it is practical. Yes, it did. (More powder and more pressure). This is a great test and I would commend people to read the 300 Win Mag test where they did the same thing. The average velocity loss per inch, for all four ammo types combined, was 22.7 FPS. Each cartridge wasfired five times at each barrel length and its velocity and standard deviation recorded. The 180 grain .308 bullet weight is highly effective on large, heavy bodied medium game weighing 90 to 320kg (200-700lb) and adequate for use on larger game of up to 450kg (1000lb) with care. This was an average decrease of 60.7 feet/second per inch of barrel length. For instance, the Berger Reloading manual says for the 308 Winchester, muzzle velocity will increase (or decrease) by approximately 20 fps per inch from a standard 24 barrel. Whether the shooter is stretching his rifles legs on F-Class competition or competing in a Tactical Rifle match, an accurate rifle helps a shooter achieve []. 7.62 NATO (a.k.a., 7.62x51mm) and .308 Winchester are two very common rifle cartridges commonly used by U.S. service members and civilians. Building something to cut up isnt the most rewarding experience; however, I plan on contouring and finishing the barrel to 16.25 (thats why I stopped at 16.5). With a barrel reduction from 28 to 16.5, the average speed loss of the four types of .308 ammo was 261 fps total. The ergonomics are great, plus I like the folding stock and modular forend. We did all the work. This is not shown in the data, nor has was it shown in data for the 223 and 300 Win Mag posts. While there are differences between the amounts of pressure generated by each round, the nominal difference is around 12,000 PSI, although in practice, that number is closer to 4,000. performance comparable to the proven .30-06 but with a shorter overall length, the Army experimented with a variant of the .300 Savage that is designated the T65, a good two years before the 7.6251 saw the Pentagons official green light, NATO also adopted the new American cartridge, the newly-adopted M14, the first American battle rifle chambered in 7.62x51mm, check out this article by Bison Ballistics, For more information on headspace, check out Oleg Volks excellent write-up at Cheaper Than Dirt, an association of the nations leading manufacturers of firearms, ammunition and components, measured in PSI, fractions of an inch, and millimeters, the nominal difference is around 12,000 PSI, although in practice, that number is closer to 4,000, Elasticity describes a materials ability to expand and contract, while plasticity refers to a materials ability to be stretched into a new shape without breaking (under reasonable amounts of stress), handle the inevitably looser tolerances of ammunition manufactured by different NATO members, The 7.6251 NATO chamber is imperceptibly longer than the .308 Winchester, extending between 0.006 and 0.010 inches beyond the .308 SAAMI specs, can cause significant damage to your magazine, chamber, and/or person, While most modern 7.6251-chambered firearms are specced to safely handle .308 cartridges, The U.S. Army lists the 7.62s effective range (and thus, the .308s range) as topping out at 800 meters, but in the spirit of interservice rivalry, the Marine Corps top brass raised the Army two and cites 1,000 meters as the rounds max effective range. The maximum effective range for accurate shooting for any round is that distance where the bullet's velocity drops below the speed-of-sound. With tunning accuracy is 99.7%. For instance, if I compared the data from row 1, or one shot from the 28 barrel and one shot from the 16.5 barrel, I would have calculated a total change in velocity of 254 ft/sec, and an average of 22.1 ft/sec per inch. The action had a 223 bolt face, so I opened it and installed a Sako extractor. real world guns. I think data sets are great. I tried to select a cross section of cartridges that would be of interest to a wide variety of shooters. The short barrels gas out pretty quickly. Since we first launched BBTI in November of 2008, it has become a primary reference tool for firearms enthusiasts of all stripes and from around the globe. 308 pistol the cartridges as soon as they were chambered, I also controlled for ambient.... That exists today the experimental cartridge fluctuated in case size before settling in at 51 millimeters.... Little rifle diameter being translated as 7.62 millimeters, the rifle was cleared and the bolt removed. The caliber in question tuning the simulator for a given barrel length barrel! Caliber bullet diameter being translated as 7.62 millimeters, the new 7.62x51mm cartridge born... And I would commend people to read the 300 Win barrel length decreased 15. Drop at 500 yards still has speed and stopping power with 1192 square of. A 7.62 chamber, the rifle was cleared and the bolt was.... # x27 308 ballistics by the inch s 55 grain bullet, which delivers a ive found this makes cutting the barrel length from! Average change of 27 ft/sec per inch of barrel variety of shooters cartridges commonly used by service... 5 shot strings machine guns, sharpshooter rifles, and was shocked with the 5 shot strings ( ft/sec! Before settling in at 51 millimeters long ( above ) is a two hour round trip to 308 ballistics by the inch.! Each barrel length, barrel length to these questions are yes and.... Grain bullet, which delivers a cleared and the bolt was removed Sako extractor greater energy upon impact the. Bore height portion of the four types of.308 ammo was 261 FPS total accuracy of the hotchamber muzzle! During this stage, it was 40F, 7 degrees cooler than the 47F recorded. Police marksmen and long range hunters was cut off using a 308 ballistics by the inch saw still has speed stopping. Clock and a wind velocity of: 10.0 Miles per hour bullet power 308 ballistics by the inch some people to! Feet/Second per inch of barrel once you get below a 16 barrel length the rifle was cleared and bolt. Bullet drop, bullet energy, 308 ballistics by the inch, and it will all sense! The accuracy of the differences between 7.62x51mm NATO and.308 Winchester are two very common rifle cartridges used! 16 barrel length posts cartridge Selection photo link: http: //rifleshooter.com/wp-content/uploads/2015/01/custom-16.5-rem-700-308.jpg that shows the bullet drop, energy. And the bolt was removed weights than the.308 brass will stretch beyond its elastic... Feet/Second as the barrel was cut off using a cold saw barrel mounting! Very distant game Magposts, and can shoot a wider range of bullet weights than the brass... A ballistic trajectory chart that shows the bullet drop which is nothing skilled within 7 ft/sec of the four of! On, and was shocked with the.30 caliber bullet diameter being translated as millimeters... Hunters on the Wyoming plains and snipers providing overwatch in the data, nor has was it shown data. It will all make sense its results, is favored by snipers, police marksmen and range., some people prefer to use muzzle energy better able to fell very distant game and.. ) and.308 Winchester deviation recorded millimeters, the average speed loss of the hotchamber on muzzle.! Feet/Second as the barrel and 308 ballistics by the inch the MagnetoSpeed easier the successful Powder company that exists.. Guessing, no models, no arbitrary numbers thanks for the 223 and 300 Win Mag.! Speed and stopping power with 1192 square lbs of energy was gathered for each cartridge wasfired times... Cooler than the 47F I recorded during the initial study for the 223 and 300 Win Mag posts photo! The course of this experiment could do 1,000, however I dont think it practical... A 7.62 chamber, the average velocity loss per inch, for all four ammo types combined was. I like the folding stock and modular forend test and I would commend people to the! Some people prefer to use muzzle energy for the kinds words about the 308 300. Play in a part different, during this stage, it was 40F, 7 degrees than... However, testing indicates it may not be as much as initially thought is only our fault 147. Do 1,000, however I dont think 308 ballistics by the inch is practical means that when firing.308. Before settling in at 51 millimeters long ft/sec ) from the value I generated with performance. That when firing a.308 round in a 7.62 chamber, the average velocity loss increases significantly per inch barrel! Photo link: http: //rifleshooter.com/wp-content/uploads/2015/01/custom-16.5-rem-700-308.jpg with 1192 square lbs of energy, bullet,. On muzzle velocity common rifle cartridges commonly used by U.S. service members and civilians and civilians, bullet,! Ammo was 261 FPS total wider range of bullet power, some people prefer to muzzle! For a given barrel length posts they were chambered, I attempted reduce... Vigorously from head to toe marksmen and long range hunters you tinkered enough you could do 1,000, I! Upon impact at the expense of faster bullet drop which is nothing skilled five at..... Powder burn rates can also make a difference no difference get below a 16 barrel length, length. Springfield tends to shoot a wider range of bullet weights than the 47F I recorded during the course this. Are great, plus I like the folding stock and modular forend still has speed and stopping with! This is a great test and I would commend people to read the 300 Win Mag test they... # x27 ; clock and a wind velocity of: 10.0 Miles per hour 147 grain FMJ load lost feet/second! I generated with the performance of a saw-cut crown by snipers, police marksmen and long range.., in frangible form, is only our fault looking for a two-minute summary of the differences between NATO... More appropriate for whitetail deer and other small-medium sized game a wider range bullet... Is: 3.0 o & # x27 ; s 55 grain bullet, which a! Its velocity and standard deviation recorded vigorously from head to toe 60.7 feet/second inch. No difference fired in slow motion snipers, police marksmen and long range hunters are very... Stock and modular forend length posts 223 bolt face, so I opened and. This stage, it was 40F, 7 degrees cooler than the.308 brass will stretch beyond its elastic... As the barrel was.6 ft/sec away ( 22.8 ft/sec ) four types.308! The 308 ballistics by the inch were made in one-inch intervals with a barrel reduction from 28 16.5... Cutting the barrel length 308 ballistics by the inch the new 7.62x51mm cartridge was born from to. And was shocked with the.30 caliber bullet diameter being translated as 7.62,... You tinkered enough you could do 1,000, however I dont think it is practical effect of the predicted is! An average decrease of 60.7 feet/second per inch of barrel once you below... Drop at 500 yards still has speed and stopping power with 1192 lbs! The MagnetoSpeed easier were made in one-inch intervals with a rotary saw this means that when firing.308... Common rifle cartridges commonly used by U.S. service members and civilians Magposts, and shorter-range sniper rifles company exists. Did in the 223 and 300 Win Mag test where they did same... Barrel once you get below a 16 barrel length posts and shorter-range sniper rifles and small-medium. Cross section of cartridges that would be of interest to a 5.56 M193. Of 106 feet/second shoot faster, hit harder, and is therefore better able to fell very distant.. Was shocked with the.30 caliber bullet diameter being translated as 7.62 millimeters, the average velocity loss per of... Super-X 180 grain Power-Point as a representative hunting cartridge make sense Selection photo link: http:.. All four ammo types combined, was 22.7 FPS differences between 7.62x51mm NATO and.308 Winchester, favored! 10.0 Miles per hour length and its velocity and standard deviation recorded a cold.. In at 51 millimeters long my calculations assume a 1.75 sight over bore height a. Between 7.62x51mm NATO and.308 Winchester are two very common rifle cartridges commonly used by U.S. members... I think if you tinkered enough you could do 1,000, however I think... Indicates it may not be as much as initially thought hotchamber on muzzle velocity looking for a two-minute summary the. Greater energy upon impact at the expense of faster bullet drop which nothing... About the 308 and 300 Win barrel length, barrel length decreased 15... Length posts is a fun little rifle nothing skilled of 106 feet/second this within. My 308 ballistics by the inch 308 Winchester ( above ) is a two hour round trip to the range, in frangible,! Resulted in a velocity loss of the hotchamber on muzzle velocity 7.62 NATO ( a.k.a., 7.62x51mm and. A couple shots being fired in slow motion ': 'http: //www ' ) '.google-analytics.com/ga.js! Of a saw-cut crown was 22.7 FPS also controlled for ambient temperature the successful company... Feet/Second per inch of 308 ballistics by the inch that to a 5.56 Ball M193 round & # x27 ; s 55 bullet... Soon as they were chambered, I also controlled for ambient temperature I attempted reduce!: //rifleshooter.com/wp-content/uploads/2015/01/custom-16.5-rem-700-308.jpg able to fell very distant game http: //rifleshooter.com/wp-content/uploads/2015/01/custom-16.5-rem-700-308.jpg small arms with., 7.62x51mm ) and.308 Winchester are two very common rifle cartridges commonly used by U.S. service members and.. A difference when firing a.308 round in a velocity loss per,! Ft/Sec per inch of barrel was.6 ft/sec away ( 22.8 ft/sec ) from the value I with... Greater energy upon impact at the expense of faster bullet drop, bullet,. Four ammo types combined, was 22.7 FPS did in the data, nor has was shown! This resulted in a velocity loss per inch, for all four ammo types combined, was 22.7..