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AR 223 velocity
- Thread starter krw
- Start date
Barrels can be unpredictable... in many aspects, accuracy, velocities, etc.
This should help show what is meant by the above comment.
( Note sometimes the barrel lost velocity after gaining an inch... )
And the test good or bad , at least shows you an idea of what to expect.
https://rifleshooter.com/2014/04/22...gth-a-man-his-chop-box-and-his-friends-rifle/
This should help show what is meant by the above comment.
( Note sometimes the barrel lost velocity after gaining an inch... )
And the test good or bad , at least shows you an idea of what to expect.
https://rifleshooter.com/2014/04/22...gth-a-man-his-chop-box-and-his-friends-rifle/
The difference in muzzle velocity due to the difference between a mid-length gas system and a rifle-length gas system will be essentially inconsequential. The graphic below shows the difference between the muzzle velocities of a 16” AR-15 carbine with a carbine gas-system compared to the muzzle velocity of that same barrel with the gas system completely clamped off. The difference is only 23 FPS.
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My LabRADAR gave the following results for a 16" DI with 10 rounds each:
75 grain Hornady Match 2504 FPS, ES 96 FPS & SD 35 FPS
75 grain Hornady Black 2390 FPS, ES 25 FPS & SD 13 FPS (also shot 1 hole @ 100 yards, about 0.5")
75 grain Creedmoor Sports 2570 FPS, ES 87 FPS & SD 43 FPS
Needless to say I wish I could find more Hornady Black!!
75 grain Hornady Match 2504 FPS, ES 96 FPS & SD 35 FPS
75 grain Hornady Black 2390 FPS, ES 25 FPS & SD 13 FPS (also shot 1 hole @ 100 yards, about 0.5")
75 grain Creedmoor Sports 2570 FPS, ES 87 FPS & SD 43 FPS
Needless to say I wish I could find more Hornady Black!!
This. The common 25 fps/in estimate is often so far off as to be completely worthless.
For example I’m currently working with a 20” barrel that runs faster than my previous 24”. Nothing special about either one, just variation between different barrels.
I’m a lot more interested in which barrel shoots it’s accuracy loads the fastest, but there’s no good way to tell that without experimenting.
You have a logical problem with that argument.
The point was not asking for which barrel length produces x velocity.
If we have 3 barrels,
X=3100fps, 29"
Y=2950fps, 16"
Z=2900fps, 20"
No matter the barrel length, we can assume that with 1" shortened from the barrel length, we will have on average 25fps less MV.
X=3075fps, 28"
Y=2925fps, 15"
Z=2850fps, 18"
Nope. The problem in your example is that you’re only considering those barrels. (Although as you wrote it, that 15” barrel is faster than the 18” which is kind of my point.)
Did you ignore the example of my 20” and 24” barrels? Because that real world data being different than the theory is exactly what I’m talking about.
if you’re assuming all barrels of a given length produce the same velocity, you’re way behind the curve. There can be huge variations between different barrels; 100fps or more difference is so common nobody thinks twice about it, but you’re telling me we can predict one will be 50 fps faster than another? That’s barely a blip in the noise. Heck a lot of the time you’ll see more velocity change than that just across the lifetime of the same barrel, sometimes within the first couple hundred rounds as it breaks in.
So what is your take on this?
Pick 16" because it might be faster than the 18"?
Really?
The truth is that barrel length matters and there have been made tests that conclude that 1" is roughly 25fps.
Unfortunally you having one anecdote does not have anything to do with this.
The truth is that when making decisions you have to have some baselines that are set on hard data. Not one guy and his one barrel that did not work for whatever reason thay may be.
Surely you can see that?
To OP, considering practical means of that 50fps, I would not take 18" if you are planning on moving and shooting with it. I'd say you need to give yourself some real reason to go 18".
18" should carry well in the back though for hunting purposes, but it's benefit is not really noticeable.
I manage to do 'tactical' shooting with the 16" and a suppressor but it is harder to change shooting positions quickly, the barrel end will take short time period before catching up to the gun hand movement. Particularly going to prone and back up.
16" should be good enough for quite long distances. If I had 18" I would not cut it down but I'd probably would not keep the suppressor on so often when doing training.
For semi, 16" is a good overall length, 18" is for those reaching slightly better trajectory.
Always better if you can handle and preferably shoot some sessions with both lengths to feel the differences.
18" should carry well in the back though for hunting purposes, but it's benefit is not really noticeable.
I manage to do 'tactical' shooting with the 16" and a suppressor but it is harder to change shooting positions quickly, the barrel end will take short time period before catching up to the gun hand movement. Particularly going to prone and back up.
16" should be good enough for quite long distances. If I had 18" I would not cut it down but I'd probably would not keep the suppressor on so often when doing training.
For semi, 16" is a good overall length, 18" is for those reaching slightly better trajectory.
Always better if you can handle and preferably shoot some sessions with both lengths to feel the differences.
Don’t over complicate it. I already said what my take on it is when I agreed with Tony.
Sure, the longer barrel is likely to be faster. By how much is a crap shoot, and the 25 fps/in number is practically worthless except as a feel-good answer for people who don’t know any better. You don’t know the real number until you actually test that particular example. If you measured a lot of different barrels you’d see this is true; I’m not basing this on one example.
If the OP is actually interested in learning something, this is a more useful takeaway than anybody’s guess. He should be able to come to the realization that for all practical purposes it’s not worth worrying about the small difference in barrel length.
Look, when you shorten a barrel it is bound to lose velocity.
Barrel tightness and wear affect to MV also.
But with certain barrel length, you can expect certain MV. There is no magic behind it. Yes, barrels have variance in MV. But there is no getting around the fact that barrels are on average 25fps faster per inch.
As an analogy, someone is asking whether to buy a car with 1.6l or 1.8l engine.
Instead of giving fact based answer that relies on statistics of engine burn capacity ratios, you advise him that no matter which one he buys, either one of them could have more performance. While that is true with a bad car manufacturer, by default that 0.2l will add a known average to performance. No magic.
Gun barrel is exactly same as engine cylinder. Longer barrel has more burn capacity, thus giving more thrust.
He needs hard data because it is the only way to make an educated decision.
Barrel tightness and wear affect to MV also.
But with certain barrel length, you can expect certain MV. There is no magic behind it. Yes, barrels have variance in MV. But there is no getting around the fact that barrels are on average 25fps faster per inch.
As an analogy, someone is asking whether to buy a car with 1.6l or 1.8l engine.
Instead of giving fact based answer that relies on statistics of engine burn capacity ratios, you advise him that no matter which one he buys, either one of them could have more performance. While that is true with a bad car manufacturer, by default that 0.2l will add a known average to performance. No magic.
Gun barrel is exactly same as engine cylinder. Longer barrel has more burn capacity, thus giving more thrust.
He needs hard data because it is the only way to make an educated decision.
That analogy works against you more than it helps your argument. There may be even more variables in engines than barrels to really muddy the waters and make displacement based performance estimates a moot point.
You have forced induction/naturally aspirated, direct injection/port injected, bore vs. stroke, fuel type, maximum rpm, compression ratio, fuel/ignition maps geared towards performance or economy. The list goes on, and it makes generalised statements about power to displacement ratios completely useless.
I've certainly used rule of thumb calculations to choose barrel lengths, but I wouldn't hang my hat on them since they are wrong at least as often as they are right.
Wrong. That’s where you’re missing real world experience, and the point I’m making. It’s really common for one barrel to be 100+ fps faster or slower than another of the same length.
If you want an analogy, this is like worrying about a 25 fps change in velocity due to temperature when your load has 100+ fps ES. It’s pointless to concern yourself with a small change in the average when the variation between samples is several multiples greater.
Some of y’all on the ‘hide are really hard headed lately.
Here’s a specific example comparing the muzzle velocity of a Noveske 16” Recon barrel with a mid-length gas system to that of a Noveske 18” SPR barrel with an intermediate-length gas system. Both barrels have a Noveske Match Mod 0 chamber and both barrels have a 1:7” twist.
The muzzle velocities shown in the graphic below were obtained using the same lot of Hornady 5.56mm 75 grain TAP T2 ammunition. Both of the muzzle velocities were from 30-shot strings over the same chronograph on the same day. The difference in muzzle velocities was 44 FPS.
Here's some additional data on the subject matter. The same 18” SPR barrel was compared to a Noveske 20” barrel with a rifle-length gas system that also has a Match Mod 0 chamber and a 1:7” twist. As before, a 30-shot string of the same Hornady TAP T2 ammunition was fired over the same chronograph on the same day. The difference in muzzle velocities was 106 FPS.
…
repeated from my previous post . . .
The difference in muzzle velocity due to the difference between a mid-length gas system and a rifle-length gas system will be essentially inconsequential. The graphic below shows the difference between the muzzle velocities of a 16” AR-15 carbine with a carbine gas-system compared to the muzzle velocity of that same barrel with the gas system completely clamped off. The difference is only 23 FPS.
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Why not split the difference and go with a 17"? https://www.precisionreflex.com/Detail.aspx?PROD=1424262&CAT=13005
For what it's worth, I feel like an 18" barrel with a rifle-length gas system is the sweet spot for most ARs, and I have a handful of 18" ARs in different calibers (5.56, 6.5 Grendel, 6.5 Creedmoor). I also have an 11.5" 5.56 AR pistol, and am now finishing up a nice 14.5" to split the difference. Build your rifle for your intended application, and don't overthink it. You'll eventually end up with a safe full of different lengths in the long-run anyway.
If you can only have one, it's hard to go wrong with a 16" for a jack of all trades rifle.
For what it's worth, I feel like an 18" barrel with a rifle-length gas system is the sweet spot for most ARs, and I have a handful of 18" ARs in different calibers (5.56, 6.5 Grendel, 6.5 Creedmoor). I also have an 11.5" 5.56 AR pistol, and am now finishing up a nice 14.5" to split the difference. Build your rifle for your intended application, and don't overthink it. You'll eventually end up with a safe full of different lengths in the long-run anyway.
If you can only have one, it's hard to go wrong with a 16" for a jack of all trades rifle.
I'd buy that right now just for giggles if it was at least an 8 twist. Don't really get how its chrome molly and stainless though.
I'm a sucker for odd barrel lengths for some reason.
18” rifle length is smoother.
All things being equal.
And I find it easier to hit a higher node easier with lever powder and 77gr tmk. Node is wider, velocity is easily 75fps faster.
I see no value in 16” barrels in general. And I still got a few.. should turn em into 11.3.
is adco still good to go for having barrels chopped? With the last 5-7 years of ez to find components hardly worth dickin around cutting shit down.
All things being equal.
And I find it easier to hit a higher node easier with lever powder and 77gr tmk. Node is wider, velocity is easily 75fps faster.
I see no value in 16” barrels in general. And I still got a few.. should turn em into 11.3.
is adco still good to go for having barrels chopped? With the last 5-7 years of ez to find components hardly worth dickin around cutting shit down.
