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I have a new rifle that is 100 fps slower than book max loads but at the book max powder volume. Has anyone else ever had this issue. I am assuming pressure = velocity. If that is so, then it seems safe to go slightly above "book max" in this rifle to reach top end velocity?? What say you? And what is the reason that book loads are as much as 150 fps slower in this rifle? I have double checked my pro Chrono and this is consistent across a number of different powders. I know some manuals use a 24" barrel vs my 22" but the discrepancy still seems way off. Looking for everybody else's "2 cents". Thanks, John.
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Because the book wasn't made with your rifle. Throat, chamber, internal barrel dia. choice of powder primer and bullets can all affect your pressure and velocity.
I have some loads that are maxed out 1-2 grains below "book", and others that are maxed out a few grains above. I can swing my velocities 200 fps just by changing primers and brass, and in some instances adjusted my powder charges accordingly.
Last edited by antelope_sniper; 09/01/15.
You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.
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I have a Sako 22-250 that doesn't even get going until I'm a couple of grains above typical listed maximums.
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My 7mm-08 with 140 Accubonds over 44 grains of RL-15 is at 2780 fps, with absolutely no pressure signs. This is way low of the web-site data shown below and I felt I should be able to exceed 2780. So, after viewing this site... http://sed88.tripod.com/rem7/peth.html, which maxes out at 44.5 grains of Varget with 140 Nosler BTs for 2950 fps, I slowly went up and stopped at 46 grains for about 2850 fps and still no pressure signs. I wasn't trying to get to 2950 fps. I haven't measured, but I attribute this to an oversize bore diameter.
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If you look at several different "books", you will see different results posted. I interpolate from multiple books data and move forward carefully watching the chrony and looking for signs. See antelope sniper's response above. Add that you have a different measuring device and distance from the barrel also, and EVERY barrel is different. jmho Tim
PS- Yes there are slow and fast barrels. Each must be treated as the individual that it is.
Last edited by michiganroadkill; 09/02/15.
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Pressure does equal velocity, with a few exceptions (secondary ignitions, etc). There are RARELY any fast barrels...
Pick-up your powder bottle, or your manual. They have this printed warning saying "Drop loads 10% when switching lots". So, there is your swing amount.
Book data also gets shoot in SAAMI minimum spec equipment, you have a production rifle; not the Same thing.
I'm a firm believer in the theory of " If it bleeds, I can kill it".
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I had a Freedom Arms .454 that ran about 100 feet per second slower than any I read about. Being a wildcatter, I just increased the powder to get the velocity I wanted. My favorite load was a 240 grain Freedom Arms bullet at 2,014 feet per second. Killed lots of jack rabbis with it.
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Pressure does equal velocity, with a few exceptions (secondary ignitions, etc). No, pressure over time equals velocity; peak pressure, which is what the manuals list, does not. The difference is that some barrel or load conditions can cause high peak pressure without meeting published velocity. You guys that think you can just load to match published book velocity are going to get bit sooner or later.
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If we want to get picky, it's pressure over change in volume.
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Not trying to be picky, just reasonably accurate for safe loading practices.
High peak pressure might blow up your gun, but does not necessarily translate to increased velocity. Estimating pressure based on velocity, especially velocity measured in a different barrel, is not a safe loading practice.
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Wouldn't that principle be more applicable if you are comparing velocity between different powders with different burning rates?? If you are consistently recording -100fps velocities for progressively increased powder volumes, up to book max loads, then wouldn't it stand to reason that your particular firearm just needs a slight increase to reach near published velocities???
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Not trying to be picky, just reasonably accurate for safe loading practices.
High peak pressure might blow up your gun, but does not necessarily translate to increased velocity. Estimating pressure based on velocity, especially velocity measured in a different barrel, is not a safe loading practice. Ridiculous. What exactly do you think is causing the barrels to be slow? David
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I have a new rifle that is 100 fps slower than book max loads but at the book max powder volume. Has anyone else ever had this issue. I am assuming pressure = velocity. If that is so, then it seems safe to go slightly above "book max" in this rifle to reach top end velocity?? What say you? And what is the reason that book loads are as much as 150 fps slower in this rifle? I have double checked my pro Chrono and this is consistent across a number of different powders. I know some manuals use a 24" barrel vs my 22" but the discrepancy still seems way off. Looking for everybody else's "2 cents". Thanks, John. How many powders have you tried? 1 powder isn't enough to just state that you have a slow barrel. More than likely, it's the powder itself that isn't delivering the speed your after.
"Give a lazy man the toughest job, and he will find the easiest way to do it"
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I have tried primarily one powder but have played a bit with a couple others. It seems to be a consistent observation.
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The reason I ask is because I have a .243 that happens to be the same exact type of rifle used in the testing of my Hornady manual, and with IMR4350, H4831, and IMR7828, it gets exactly the velocity that the book says it should get. Between 2900-2950fps. However, RL22 goes over 3100, and the brass is expanded no more than the other 3 powders, so I will take an extra 150fps Some lots of powder are just different from others, and that can be a big factor.
"Give a lazy man the toughest job, and he will find the easiest way to do it"
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Within the same powder, would it be permissible and safe to expect the same velocity as published with a modest adjustment of powder, not over compression?
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Watch your pressure signs, work up carefully, and see where your rifle groups the best.
You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.
You cannot over estimate the unimportance of nearly everything. John Maxwell
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Pressure does NOT equal velocity. Some powders produce higher pressure to achieve the same velocity as others.
There are a lot of things that can affect pressure. Temperature, altitude, chambers, bores, and i'm sure there are others also.
Example of temp: Friend of mine had a near book max load he developed for a rifle in early spring, no pressure signs. In July he went out with same load to do some penetration testing, primers blew out and it was all he could do to open the bolt.
And yes there are slow and fast barrels. 2 of the Reminton 700 30-06's in my house shoot the same load of IMR 4350 in R-P cases, with the same primer, with a 165 gr Hornady. One of them gets 2720 fps the other right at 2900 fps, and they both have 22" barrels. The load shoots accurately out of both rifles.
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Pressure does NOT equal velocity. Some powders produce higher pressure to achieve the same velocity as others.
There are a lot of things that can affect pressure. Temperature, altitude, chambers, bores, and i'm sure there are others also.
Example of temp: Friend of mine had a near book max load he developed for a rifle in early spring, no pressure signs. In July he went out with same load to do some penetration testing, primers blew out and it was all he could do to open the bolt.
And yes there are slow and fast barrels. 2 of the Reminton 700 30-06's in my house shoot the same load of IMR 4350 in R-P cases, with the same primer, with a 165 gr Hornady. One of them gets 2720 fps the other right at 2900 fps, and they both have 22" barrels. The load shoots accurately out of both rifles. Pressure = Velocity There's no way around it. No one is talking about comparing different powders - this is about book powder charges not reaching book velocity. Loads that shoot fast in high heat do so because of high pressure (caused by the xs heat). There's no such thing as a "fast barrel" or a "slow barrel". There are barrels with tight cut chambers and precison bores that make max velocity (and pressure) w/ a minimal powder charge and there are sloppy cut chambers and sloppy bores that make less pressure and less velocity with the same powder charge. The powder charge to reach the same velocity can vary significantly, the pressure will be close to the same. David
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Pressure creates velocity but pressure does not equal velocity.
And if this is about " book powder charges not reaching book velocity", that is because different pressures in different rifles create different velocities.
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