The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading More barrel length vs. VelocityGo | New | Find | Notify | Tools | Reply | |
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For those who ask have much affect barrel length has on velocity. Two 7.62 X 41s ( home grown ) Mauser With 16" Douglas barrel Stevens Mod 200 with a Shaw 24" barrel Load = 30.5 grains aa 2015 Case = reformed from .257 roberts, RP Primer #34 #1 Bullet 150gr. RN. ABC., OAL=2.400" 16" barrel, Avg. Velocity = 2015fps. 24" barrel, Avg. Velocity = 2150fps. #2 Bullet 150gr. BT., Balistic tip, 16" barrel, Avg. Velocity = 2078fps. 24" barrel, Avg. Velocity = 2205fps. DELTA #1 bullet, 2150 - 2015 = 135 fps. DELTA #2 bullet, 2205 - 2078 = 127 fps. Comment: These were somewhat mild loadings and a minute amount of unburned powder was evident. Same two rifles. Load = 34.7gr. I4895 compressed, SL-42 case #34 primer. Delta Vel. = 155FPS. Delta Vel. = 143 FPS. Hmmmmm. Seems like the rule of thump might just change with variables.  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | ||
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Some have experimented with 22LR and barrel length. There is ammo that peaks at 16" and there is ammo that keeps getting faster all the way to the longest barrel, 26". Quickload does a great job of predicting velocity changes with barrel length for the cartridges in quickload's library, but I lack the where-with-all to enter your wildcat's parameters. | |||
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Nice Test and I agree with your conclusion. | |||
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 MADE A MISTAKE and now will edit it. The Shaw barrel was 24"   rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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The effect of barrel length is variable depending on the energy release curve of the propellant. You see the least differences with quicker propellants and a greater difference with the classic "slow propellants" (IMR4831/IMR7828/H5010) Also remember that there are "Fast barrels" and "slow barrels" that can really screw with your perception then there are counterintuative effects you run into with propellants like the RL propellants that are dual based and bring a lot of energy into play later in the burn cycle. AD If I provoke you into thinking then I've done my good deed for the day! Those who manage to provoke themselves into other activities have only themselves to blame. *We Band of 45-70er's* 35 year Life Member of the NRA NRA Life Member since 1984 | |||
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 Good stuff Saeed  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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 Just a point of interest;the Shaw barrel took at least twice as long to clean as the Douglas barrel. In all fairness the Douglas barrel has had about 500 more rounds put through it than the Shaw. The Shaw ,however, really holds on to the copper.  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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If you're interested take a look at my data along similar lines
---------------------------------------- If you waste your time a talkin' to the people who don't listen To the things that you are sayin' who do you thinks gonna hear And if you should die explainin' how the thing they complain about Or the things they could be changing who do you thinks gonna care Waylon Jennings | |||
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[/QUOTE]  I did! and thanks for shareing. rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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I am playing with the idea of doing the same thing we did with the 223 with a 308 Winchester when I get the chance. | |||
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Sounds like a winner. I, in turn, this week will be doing it with two 6.5X55s , one with a 24" barrel and the other with a 30" barrel.  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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I am presently doing load development on a pair of 270s. One is a Mauser with a 22" Shilen barrel, the other is a pre-64 M-70 with a factory 24". With identical loads the shorter barrel has consistently been about 30fps faster. Goes to show, you gotta chronograph 'em to know what you're talking about. | |||
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Gentlemen, Using two rifles introduces another variable into this. I found this out when we got 5 Mannlicher rifles, all in 270 Winchester, with 5 scopes and Norma 150 grain SP ammo. All the rifles were brand new, same make and model. The velocity difference between them was 150 fps??!! I am still scratching my head of why. We have had 300 Remington Ultra rifles that had a higher velocity than a 30-378 Weatherby, but that is another story altogether. | |||
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The differences between the "identical" barrels and chambers is not surprising. I recall many years ago visiting the Winchester plant where they fired some 225 Winchester reference ammo in a SAAMI spec test barrel. The velocity was some 200 fps under the assessed value. No surprise expressed, simply "That barrel must have a fairly large correction." As it was explained to me many years ago, "I feel sorry for those who think ballistics is an exact science. They just don't understand the problems." | |||
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Roger Good test and Just about what I figured all along.I have spent a lot of time doing same with primers and cases. | |||
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To answer the barrel length vs velocity question, I would tend to trust using Hartmut Broemel's QuickLoad more than trying to do it experimentally. Experimentally you will end up looking at the small differences between large numbers; this is risky at best and easily can be misleading. Ken O As it was explained to me many years ago, "I feel sorry for those who think ballistics is an exact science. They just don't understand the problems." | |||
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Loud and clear ,Ken.  It would be silly to use these numbers I'm generating as a physical law. They can however, in the doing, aid in putting to rest the curiosity factor, give you some pleasure and stimulate folks like you to join in a discussion. It seems to be working. Glad I got my Mod. 35 before you gave up the ghost. rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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Exactly Saeed, it's why numbers from two diff rifles w/ diff. barrels is almsot meaningless, sorry Bartsche, because identical rifles can vary as much as 150fps. LIFE IS NOT A SPECTATOR'S SPORT! | |||
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Allan DeGroot X2 Hypothetically speaking a 1:16 twist does little good in a 12" barrel . If your shooting light bullets from a fast twist short barrel Good Luck !. Roger : You failed to mention rate of twist not that it is that critical for velocity Stats but can effect them some what. Rather than type out a long winded blah of my BS : I borrowed this from Gunners Den . What does the rifling twist rate do. The rate of rifling twist determines the optimum bullet weight for a given caliber and speed of the bullet by applying the proper spin on the bullet to prevent the bullet from yawing and pitching. Expressed in terms of the number of revolutions per inch of barrel length, this ratio is commonly expressed by designations such as 1:10, 1/10 or 1 in 10 twist, the 1 represents 1 twist, the 10 represents inches of barrel length. So, a 1 in 10 twist is, 1 complete bullet revolution every 10 inches of barrel length traveled. How do you know what rifling twist is right. A good rule of thumb is that the heavier and longer a bullet is, the faster the rifling twist rate needs to be to stabilize it in flight, therefore a lighter shorter bullet needs a slower rifling twist rate to give proper bullet spin for correct flight. Exception to the rule. If an insufficient twist rate is used, the bullet will begin to yaw and then tumble; this is usually seen as "keyholing", where bullets leave elongated holes in the target as they strike at an angle. Once the bullet starts to yaw, any hope of accuracy is lost, as the bullet will begin to veer off in random directions. A too-high rate of twist can also cause problems. The excessive twist can cause accelerated barrel wear, and in high velocity bullets an excessive twist can cause bullets to literally tear themselves apart under the centrifugal force. I leave the twist and length too professional barrel makers . One less headache .  | |||
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Don't be sorry ,Fred. these are just numbers that are being generated to be used or not as you will. I find nothing sacred here. Todays findings are interesting to be sure. Military = 2714 fps avg. Load** 139 psp Prvi., 45.9gr. DP85, PMC case, #34 primer OAL=3.015" Shaw = 2720 fps.avg.2. Military = 2707fps.  Something to be learnt here I'll bet. WAHH. rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading More barrel length vs. Velocity
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