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Posted: 9/20/2014 1:06:28 AM EDT
[#1]
10.3" barrel, 9.5" rail
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Posted: 9/20/2014 1:12:13 AM EDT
[#2]
It is measured from the breech face to the end of the threads.
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Posted: 9/20/2014 1:13:08 AM EDT
[#3]
thanks but I am more interested in exact numbers, so I can mock up different configurations. I already have a 9.5 and 10.3, but when I measure the end of the rail to the beginning of the threads, I expected there to be .3 inches of length, but was more like 1/16. 1/2" of threads minus the 10.3 would be 9.8 compared to the 9.5 in rail. I measured the rail to check and its 9.5 exactly. So whats the math when it comes to a barrel length and the actual length from the end of the upper receiver to the end of the threads when it comes to comparing to rail length? Thanks for the pic tho
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Posted: 9/20/2014 1:17:50 AM EDT
[#4]
Quote HistoryQuoted:
It is measured from the breech face to the end of the threads. So what would be the simple math if I wanted to take a specific barrel length and figure out what the length measurement would be from where the handguard begins next to the upper receiver to the end of the barrel? That way i could calculate how much barrel would stick out easily |
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Posted: 9/20/2014 2:19:46 AM EDT
[#5]
The problem with your calculation is there is still barrel & breach (as another poster pointed out) that would not be calculated.
Barrel length is the length of the entire barrel...not whats just visable.
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Posted: 9/20/2014 10:54:08 AM EDT
[#6]
Quote HistoryQuoted:
The problem with your calculation is there is still barrel & breach (as another poster pointed out) that would not be calculated. Barrel length is the length of the entire barrel...not whats just visable. I'm not sure why this is so hard to convey what I'm trying to accomplish. If a barrel is 10.5 inches long, does that mean the length if te barrel starting at the beginning of the handguard out past the end of it is 10.5 inches? |
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Posted: 9/20/2014 11:22:47 AM EDT
[#7]
There is no way to come up with a guaranteed accurate way to do this. Hand guard length is usually more than stated. A 10" hand guard is usually about 10.5, 12" is about 12.4, etc.
Varies with manufacturer of course. ETA: If you're just asking about the barrel, then I agree the distance from breech to the barrel nut should be pretty consistent among different barrels. |
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Posted: 9/20/2014 11:28:51 AM EDT
[#8]
A barrels length is measured from the barrel extension (feed ramp end), to the start of the threads on the shoulder for the muzzle device.
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Posted: 9/20/2014 11:29:15 AM EDT
[#9]
Quote HistoryQuoted:
If a barrel is 10.5 inches long, does that mean the length if the barrel starting at the beginning of the handguard out past the end of it is 10.5 inches? NO, it's @ 10.1- 10.25 from receiver to end of threads. or @ 3/8 less than that from receiver to start of threads. |
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Posted: 9/20/2014 11:31:50 AM EDT
[#10]
I think what OP is asking, is how much of the barrel is inside the upper, so he can figure out the typical distance from the end of the upper to the start of the threads. The idea being that the same amount of barrel is always in the upper, so for whatever barrel length you have you can subtract that off.
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Posted: 9/20/2014 1:10:25 PM EDT
[#11]
Quote HistoryQuoted: A barrels length is measured from the barrel extension (feed ramp end), to the start of the threads on the shoulder for the muzzle device. |
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Posted: 9/20/2014 1:49:56 PM EDT
[#12]
Quote HistoryQuoted:
I'm not sure why this is so hard to convey what I'm trying to accomplish. If a barrel is 10.5 inches long, does that mean the length if te barrel starting at the beginning of the handguard out past the end of it is 10.5 inches? Quote HistoryQuoted:
Quoted:
The problem with your calculation is there is still barrel & breach (as another poster pointed out) that would not be calculated. Barrel length is the length of the entire barrel...not whats just visable. I'm not sure why this is so hard to convey what I'm trying to accomplish. If a barrel is 10.5 inches long, does that mean the length if te barrel starting at the beginning of the handguard out past the end of it is 10.5 inches? Why don't you simply take out a tape measure and measure from the end of the receiver to the tip of the barrel threads if that is the question your asking for... Then measure the rail you want to put on. Barrel lengths are usually pretty consistent but I wouldn't count on it being what it says it is until I physically have it to measure it and the rail for myself. For instance some 14.5" barrels are longer than they say they are from members quotes in past here from a certain manufacturer but the name of that manufacturer escapes me at the moment... |
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Posted: 9/20/2014 1:51:42 PM EDT
[#13]
Quote HistoryQuoted:
That is not correct. A barrel length is measured from the face of the bolt (rear of chamber) to the physical end of the muzzle. Quote HistoryQuoted:
Quoted:
A barrels length is measured from the barrel extension (feed ramp end), to the start of the threads on the shoulder for the muzzle device. That is correct. |
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Posted: 9/20/2014 1:53:20 PM EDT
[#14]
What is the question?
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Posted: 9/20/2014 2:19:02 PM EDT
[#15]
Quote HistoryQuoted:
What is the question? He's trying to correlate internal barrel lengths with descriptions of handguards, when there is no accurate way to do that. Most manufacturers just say "7 inch" for carbine length or "9 inch" for midlength or "12 inch" for rifle length for handguards for example, and none of those will be those exact measurements. It's nomenclature not specifications. |
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Posted: 9/20/2014 2:36:27 PM EDT
[#16]
Quote HistoryQuoted:
That is not correct. A barrel length is measured from the face of the bolt (rear of chamber) to the physical end of the muzzle. Quote HistoryQuoted:
Quoted:
A barrels length is measured from the barrel extension (feed ramp end), to the start of the threads on the shoulder for the muzzle device. In the context of what the OP is looking for.... I think. |
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Posted: 9/20/2014 3:24:09 PM EDT
[#17]
Quote HistoryQuoted:
I think what OP is asking, is how much of the barrel is inside the upper, so he can figure out the typical distance from the end of the upper to the start of the threads. The idea being that the same amount of barrel is always in the upper, so for whatever barrel length you have you can subtract that off. This is exactly what I'm asking. How far it extends into the receiver not including the receiver extension. I don't give a rats ass how barrel length is measured nor that companies don't state the exact rail length. I'm asking if there is a standard amount less than the actual barrel length it would measure if you measured from the end of the top of the receiver to the end of the threads. Ie 10.5 barrel = what length when measured from the end of the top of the receiver |
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Posted: 9/20/2014 3:44:41 PM EDT
[#18]
The barrel extension is 0.990" from the rear side of the flange to the back of the extension, so there is approximately one inch of "barrel" inside the upper.
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Posted: 9/20/2014 4:16:58 PM EDT
[#19]
Some rough guesstimation leads me to say that the bolt face is between 1/10 and 1/8th inch behind the front edge of the top rail on the upper receiver. The rear face of the barrel is roughly even with the front of the top rail, the difference is the depth of the bolt face from the front of the locking lugs.
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Posted: 9/20/2014 5:52:05 PM EDT
[#20]
Quote HistoryQuoted:
The barrel extension is 0.990" from the rear side of the flange to the back of the extension, so there is approximately one inch of "barrel" inside the upper. Right right but how much of it extends into the upper not including the receiver extension? No one can take a measuremt of a barrel fr the top end of the upper receiver to the end of the threads for me? |
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Posted: 9/20/2014 6:18:20 PM EDT
[#21]
That will depend on how deep and how well the threads are machined on both the barrel nut and barrel AND how hard the barrel is torqued into the barrel nut. It will also vary on the coating thickness as well as coefficient of friction between the parts (which will vary depending on the coating type - if any).
Since all that will vary from manufacturer to manufacturer (of the barrel and extension), coating type/thickness, and how much torque is used, I doubt that it would be consisted from one to the other. Even those where the barrel assembly is coming from one manufacturer will probably vary by a bit due to all that above and others that I'm probably missing or ignoring (like temperature). But, with all that aside, if you consider the pitch of the threads (16UNF or 16 threads per inch), it is likely that the differences will be minimal. Probably less than 0.1" difference from one to another. If there's a particular barrel you are looking at, you'll probably have to call the manufacturer/supplier and ask them for a measurement. Or maybe ask them to measure several and see if there is a difference. It may not even be measurable with a tape measure (which usually only have 1/16" lines). R/Matel |
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Posted: 9/20/2014 6:20:36 PM EDT
[#22]
Quote HistoryQuoted:
Some rough guesstimation leads me to say that the bolt face is between 1/10 and 1/8th inch behind the front edge of the top rail on the upper receiver. The rear face of the barrel is roughly even with the front of the top rail, the difference is the depth of the bolt face from the front of the locking lugs. Copy that, but there has to be a standard length ya? What is that length so I would know how much to subtract from the actual barrel length to figure out how far it extends out from the top of the receiver? |
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Posted: 9/20/2014 7:04:42 PM EDT
[#23]
My 10.5" RRA barrel measures 10 3/8" from the receiver to the end of the barrel threads.
Dave N |
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Posted: 9/20/2014 7:35:20 PM EDT
[#24]
Also, different brands of barrels are not exactly as advertised as far as length. I've had many barrels sold as 16 inch that were anywhere from 16.25-17 inches.
I've also had barrels sold as 14.5 inches that were over 15 inches long.
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Posted: 9/20/2014 7:53:04 PM EDT
[#25]
Quote HistoryQuoted:
My 10.5" RRA barrel measures 10 3/8" from the receiver to the end of the barrel threads. Dave N See there we go because my Daniel defense barrel measured just longer than 9.5 inches to the beginning of the threads. |
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Posted: 9/20/2014 7:57:54 PM EDT
[#26]
Quote HistoryQuoted:....how much of it extends into the upper.... From the end of the upper receiver that is threaded for the barrel nut; from that outer-edge, the bolt-face is located 0.616" inches inwards. From this inward point, measure out to 10.5" inches. From the upper receiver where the gas tube enters, from this point measure out to 9.5" inches. This is where the end of a 9.5" inch handguard will be in relation to a 10.5" inch barrel. NOTE: This is without a muzzle device installed. |
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Posted: 9/21/2014 12:32:35 AM EDT
[#27]
Quote HistoryQuoted:
That will depend on how deep and how well the threads are machined on both the barrel nut and barrel AND how hard the barrel is torqued into the barrel nut. It will also vary on the coating thickness as well as coefficient of friction between the parts (which will vary depending on the coating type - if any). Since all that will vary from manufacturer to manufacturer (of the barrel and extension), coating type/thickness, and how much torque is used, I doubt that it would be consisted from one to the other. Even those where the barrel assembly is coming from one manufacturer will probably vary by a bit due to all that above and others that I'm probably missing or ignoring (like temperature). But, with all that aside, if you consider the pitch of the threads (16UNF or 16 threads per inch), it is likely that the differences will be minimal. Probably less than 0.1" difference from one to another. If there's a particular barrel you are looking at, you'll probably have to call the manufacturer/supplier and ask them for a measurement. Or maybe ask them to measure several and see if there is a difference. It may not even be measurable with a tape measure (which usually only have 1/16" lines). R/Matel There is no threading on the chamber side of the barrel. WTF are you talking about? The barrel nut threads onto the upper receiver effectively "sandwiching" the barrel between them. On top of that, different torque values on the barrel nut are going to account for a few thousandths difference in barrel length beyond the upper receiver, I don't think OP needs that specific of a number. OP the biggest problem you'll run into is that the majority of barrels aren't cut to their exact advertised length. A year or so back there was a big hubbub when BCM was shipping out "14.5" uppers there were measuring out at 14.7" or longer. On top of that most rails aren't the actual length as they are advertised, this can account for a large difference. You're best bet is to test out shit you already own or delve into the picture threads to find somebody with the setup you want to see if it'll work. If I may ask, what setup are you attempting to get that you're not sure about? |
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Posted: 9/21/2014 4:35:57 AM EDT
[#28]
Quote HistoryQuoted: See there we go because my Daniel defense barrel measured just longer than 9.5 inches to the beginning of the threads. |
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Posted: 9/21/2014 8:22:52 AM EDT
[#29]
OP, for actual length(ATF standards), drop a cleaning rod down the barrel on a closed bolt then measure the length to the end of the muzzle threads
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Posted: 9/21/2014 10:08:24 AM EDT
[#30]
So do y'all think it's about an 1/8" difference?
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Posted: 9/21/2014 10:34:53 AM EDT
[#31]
Topic Moved
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Posted: 9/21/2014 11:36:40 AM EDT
[#32]
Quote HistoryQuoted: So do y'all think it's about an 1/8" difference? There is no guessing when you use the blueprints to your advantage that can be found online with some extensive work searching. As I mentioned above, the bolt-face is 0.616" inwards from the outer-edge of the threaded portion of the upper receiver for the barrel nut. Also, from the outer-edge of the threaded portion of the upper receiver for the barrel nut to where the gas tube enters the upper, it is 0.445". You got the numbers you need, so you should be able to figure the rest out. |
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Posted: 9/21/2014 12:05:18 PM EDT
[#33]
As AR-4C says, the blueprints are a great resource. But here's another VERY important thing to know: most barrel makers quote a slightly lower length for their barrels than you will get with the ATF measurement process. Barrels can vary in length by as much as 1/4" within the same batch because of machining and chambering issues, and barrel makers want to keep US from goofing up on the wrong side of the "at least 16 inches" line, so they quote "16.1 inches" when that's below their minimum requirement from the lathe.
SO: measure YOUR barrel per the ATF system (from the locked bolt face to the end of the actual muzzle), and then measure on the outside from the end of the actual muzzle to the front of YOUR upper. That will give you YOUR barrel's "exposed" length, which will tell you what you need to know about rail coverage, etc. |
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Posted: 9/21/2014 1:53:32 PM EDT
[#34]
GHPorter,
Even though emtothedee's topic is titled "length of barrel from upper receiver," he is trying to factor how much a barrel will stick out past a free-floated rail. Which the difference will be where the bolt-face lies inside the upper receiver in relation to edge of the flat-top rail where the gas tube enters the upper receiver. Since, barrel length is figured from the bolt-face to the end of the muzzle. |
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Posted: 9/21/2014 5:39:02 PM EDT
[#35]
Quote HistoryQuoted:
GHPorter, Even though emtothedee's topic is titled "length of barrel from upper receiver," he is trying to factor how much a barrel will stick out past a free-floated rail. Which the difference will be where the bolt-face lies inside the upper receiver in relation to edge of the flat-top rail where the gas tube enters the upper receiver. Since, barrel length is figured from the bolt-face to the end of the muzzle. And the method I described above will give him (and anyone else) that length. No two barrels of the same nominal length can be guaranteed to be identical in actual length, so to know exactly how much barrel will stick out, do some measuring. A close approximation can be had by simply subtracting 0.50" from the nominal barrel length; that should account for the part of the barrel (including the extension) that's inside the receiver AND for the depth of the bolt face to within around 1/8" or so. |
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