Here comes another silly question but being new to the reloader game, there are things I read that are a mystery to me. Does the length of the barrel have an affect on reloading data? If say you load, 55 gr fmj for 223 Rem, will the length of the barrel have an effect on the reloading data? AR's have different length barrels from 16" to over 20", will this affect the load data and how? Thanks for responding to these silly questions but it you don't ask, you will always be guessing. 74man
Barrel length?
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Hondo 60
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No, barrel length has almost no effect on the "data".
How much powder, what powder etc.
You will find about 100fps faster for each inch of extra barrel length.
18" vs 20" inch barrel etc.
How much powder, what powder etc.
You will find about 100fps faster for each inch of extra barrel length.
18" vs 20" inch barrel etc.
AJC1
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Semi autos are driven by gas pressure so what gas system length you have, burn speed and powder volume all mater and the range published is the widest range available. Your windows of operation may be much smaller inside those published windows.
Bcwitt
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Wont affect your reloading data, will affect performance. 556 is awesome in a 20" barrel. Not so much when you shorten it. A 16" barrel is simply not a match for a 20". Dont believe it? Go shoot a 1/2" mild steel plate w a green tip. A 20" will penetrate it & leave an impressive hole. 16" barrel wont come close to that.
Varminterror
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Short barrels lose velocity because the bullet has less time exposed to driving force (pressure in the bore). But the data used is the same.
jebova2301
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You're right that it will all depend on what powder, what lengths and all that, but 100fps per inch is a stretch. If I recall correctly(don't have the Chrono results on front of me right now), the difference between my 16 and 20 inch barrels is about 125fps total.
74man, if you let me know what powder(s) you are dealing with, I can test them out tomorrow if I have any of them on the shelf.
LiveLife
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.223 Remington UMC 55 gr.MC - http://ballisticsbytheinch.com/223rifle.html
- 18" - 2983 fps
- 16" - 2943 fps
Demi-human
maybe likes firearms a little bit…
No, it does not.
Loading data is produced for Maximum Average Chamber Pressure. It deals with only the chamber pressure, it doesn’t care what length barrel is on it.
The maximum load for a given powder in a .223 7 inch pistol is the same for a 30 inch barrel .223 target rifle, but the rifle will be able to use more of the energy to accelerate the projectile to a faster speed.
Gratuitous pic of my 30” .223 Target Rifle.
Savage M12 F/TR
Varminterror
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For which cartridge have you witnessed 100fps/inch?
Typically, the velocity change per inch will be somewhere between 20-50fps/inch, depending upon cartridge size and bore diameter (expansion ratio). Berger’s reloading manual even publishes approximate velocity change per inch of barrel for each individual cartridge.
Mr_Flintstone
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Sorry, but somehow this thread brought back memories of a sign I saw in a public restroom once above the urinals.
Men shooting with short barrels should stand closer to target.
Men shooting with short barrels should stand closer to target.
Blue68f100
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On rifle rounds I normally only see 20-25 fps/inch of barrel length. I do have 1 barrel that is faster by 100-150fps than my others one, all the same length (24").
Handgun are totally different story. A short barrel 2" may give up 300 fps when compared to a 5" barrel. It's more sensitive to powder. But in general what gives the fastest velocity in a short barrel will also give the fastest in a longer barrel.
Now with gas operated guns it's all about the pressure at the port. Powders pressure curve are different. Some peak earlier than others, some produce a longer higher pressure. On a gas gun they are deigned to work at a certain pressure range. Get over the gun beats it self up, under the gun does not operate correctly. Luckily we have many ways to adj the pressure to tune a gun.
Handgun are totally different story. A short barrel 2" may give up 300 fps when compared to a 5" barrel. It's more sensitive to powder. But in general what gives the fastest velocity in a short barrel will also give the fastest in a longer barrel.
Now with gas operated guns it's all about the pressure at the port. Powders pressure curve are different. Some peak earlier than others, some produce a longer higher pressure. On a gas gun they are deigned to work at a certain pressure range. Get over the gun beats it self up, under the gun does not operate correctly. Luckily we have many ways to adj the pressure to tune a gun.
243winxb
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Different powders & bullet weights have an effect on gas port pressure. Different length barrels have the gas port at different lengths from the chamber. Gas ports diameters are not a standard size.
If i remember correctly? There was a post where IMR4198 & 40 gr bullet would not work the AR15 20" bbl action, with a maximum powder charge. Not common.
Longer barrels produce more velocity then short ones depending on powder burn rate. The slower powders tend to keep burning, producing pressure till bullet exits the barrel. https://discover.dtic.mil/ A small amount of powder will not be burnt, .5% or more.
jebova2301
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That sounds about right. Once it is a little later this afternoon, I will try running some rounds through a couple of my different uppers(16" chrome lined 1:7, 20" chrome lined 1:7, and 20" stainless 1:7.7) to see what results I get. Don't really feel like cracking off rounds too early in the morning and irritating the neighbors.
243winxb
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View attachment 1027846 Barrel length test, accuracy & powders used. http://www.accuratereloading.com/223sb.html.
JEBOVA, I will be using CFE223 powder. Both rifles have 16" barrels, one rifle has 1:7 twist, one rifle has 1:8 twist. One is a Troy PAR the other is a Kel-Tec SU16CA. Don't know it you need the twist rate but couldn't hurt to supply it. I will be loading about 1K rounds for spray and pray since I don't shoot for dead point accuracy any more. I want to hit a three inch center at about 100 yds. Thanks for your interest in my loads.
jebova2301
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I don't have that exact powder, but I have a surplus powder(wc844) where the charges and velocities the hodgdon site is giving are lining up very close to. I will use that at 27 grains to get a baseline. For 3 inch groups at 100, the fmj you have should be fine as long as your powder charges are even remotely consistent. I'll go do the testing in a couple hours after I grab some lunch and finish cleaning my garage.
westernrover
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Barrel length won't result in a practical change in peak pressure, so the data indicating what powder charge masses are safely within specificed and tested pressures does not vary with barrel length. However, substantial changes in barrel length can affect what powder is best suited. Most people observe that the powder that produces the highest velocity in a long barrel will also produce the highest velocity in a short barrel. Even so, the efficiency and economy of slow-burning powders is comparatively poor. While they do deliver higher velocity in short barrels, they deliver much more in longer barrels. For example, you may use twice as much of a slow-burning powder to get 500 fps more out of a long barrel, but will still burn that double mass of powder only to get 50 fps more out of the shortest barrel.
If it's not barrel length, what is the factor that determines when a powder is too slow for a gun? Is it the chamber and case volume? The ratio of case volume to bore diameter?
If it's not barrel length, what is the factor that determines when a powder is too slow for a gun? Is it the chamber and case volume? The ratio of case volume to bore diameter?
Bcwitt
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It is "mostly" chamber volume & bore. Other factors are there as well. We could say it is ultimately pressure. There isnt really a mathematical formula to calculate it exactly. It is ultimately pressure, that most of us do not have an accurate way to measure. All you can really go by is pressure tested data.
Thank you jebova, I am interested as to what you discover. Thanks again and I am not in a hurry so don't rush to get the results. I still waiting on getting more primers. but will load other rifle and pistol cases. They are ready except for the powder and bullet. I am anxious for this weather to cool down, Nor Cal has been in the 90"s for quite some time, I like winter. Nice and cool.
243winxb
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Pressure in the chamber remains the same, no effect from barrel length. (Hodgdon)
Put a can/suppressor on the end of the AR 15 barrel & Hornady said- https://www.hornady.com/support/superformance-in-gas-operated-firearms
Put a can/suppressor on the end of the AR 15 barrel & Hornady said- https://www.hornady.com/support/superformance-in-gas-operated-firearms
Varminterror
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Technically, there is a formula to calculate the peak pressure, because that is EXACTLY what Quickload does.
Our pressure peak typically happens within the first three inches of bullet travel (read “typically” to mean “almost always, but I’m hedging my bet against one dumbass who wants to pontificate the few exceptions which exist”), such the peak pressure is completely oblivious to how much barrel remains in front of the bullet after the instance of peak pressure. So unless you’re cutting your 300 win mag to a 1.5” barrel, you don’t need to worry much about barrel length influencing peak pressure.
Bcwitt
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That is all based on tabulated data. It is not a mathematical equation.
Varminterror
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It’s mathematical interpolation of empirical data.
There’s no tabulated data for the wildcatting we do with QL, it’s calculated interpolation based on empirically based regressions.
Bcwitt
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Interpoling is using existing data & drawing a theoretical conclusion. That is not an equation.
Varminterror
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When it’s a formulaic regression, it certainly is.
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