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Posted: 11/6/2014 9:04:09 AM EDT
| I know there is a slight loss in velocity from 16.1-14.5 using 5.56, but what does performance look like with a 13.5 inch barrel using 5.56? |
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Also consider gas port length and size, buffer weight etc. They all impact velocity/performance to varying degrees.
A shoter barrel is generally a compromise of some sort,even it it is only velocity you're giving up. Did you have a specific set of circumstances in mind that you were looking for clarification on? |
| I was leaning towards a 14.5 barrel for a new build but I want to use a surefire muzzle brake. It is 2.70 inches in length which would bring the OAL to 17.2. Now Im thinking about a 13.7 inch barrel with the same brake; this would give me an OAL of 16.4. Thats more desirable to me. Is the shorter length worth the lost velocity? Will it be just as accurate out to 200 yards as a 14.5 or 16 inch barrel? |
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I was leaning towards a 14.5 barrel for a new build but I want to use a surefire muzzle brake. It is 2.70 inches in length which would bring the OAL to 17.2. Now Im thinking about a 13.7 inch barrel with the same brake; this would give me an OAL of 16.4. Thats more desirable to me. Is the shorter length worth the lost velocity? Will it be just as accurate out to 200 yards as a 14.5 or 16 inch barrel? I don't have that brake, be sure to deduct the overlap (threads) when doing your measuring if you're trying to stay NFA legal, for barrel/OAL stuff. It may come in shorter than 17.2 inches... Velocity all by itself has very little to do with accuracy. So a quality barrel, shooting quality ammunition is still accurate, regardless of barrel length for most purposes. A reduction in velocity will impact how har out a given bullet will reach, with X amount of energy. Going from a 16" barrel to a 14.5" barrel, the velocity loss will be minimal and accuracy (assuming quality parts) will be a wash. Going from a 16" barrel down to a 10.5" barrel, the velocity drop can be significant, but accuracy retained. My 10.3" 5.56 barrel is every bit as accurate as one of my 16" 5.56 barrels. At the end of the day, my ability alone is holding those weapons back, not the barrel length. |
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Define performance Sure its going to have less velocity. Its still plenty lethal. Lots of bad guys have been dropped overseas with 10.3" guns and FMJ rounds don't tell that to the "data" crowd, its impossible for M855 to do anything but icepick past 75 yards according to the "data" |
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I was leaning towards a 14.5 barrel for a new build but I want to use a surefire muzzle brake. It is 2.70 inches in length which would bring the OAL to 17.2. Now Im thinking about a 13.7 inch barrel with the same brake; this would give me an OAL of 16.4. Thats more desirable to me. Is the shorter length worth the lost velocity? Will it be just as accurate out to 200 yards as a 14.5 or 16 inch barrel? That is a question only you can really answer based on what your needs/wants are, but if it were me I'd go for as short as I could (16.1" assuming a non SBR). It will definitely be just as accurate, all other things being equal. |
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don't tell that to the "data" crowd, its impossible for M855 to do anything but icepick past 75 yards according to the "data" Quoted:
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Define performance Sure its going to have less velocity. Its still plenty lethal. Lots of bad guys have been dropped overseas with 10.3" guns and FMJ rounds don't tell that to the "data" crowd, its impossible for M855 to do anything but icepick past 75 yards according to the "data" Is that the same crowd that says XM193 bounces off heavy clothing? 
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Quoted: That is a question only you can really answer based on what your needs/wants are, but if it were me I'd go for as short as I could (16.1" assuming a non SBR). It will definitely be just as accurate, all other things being equal. Quoted: Quoted: I was leaning towards a 14.5 barrel for a new build but I want to use a surefire muzzle brake. It is 2.70 inches in length which would bring the OAL to 17.2. Now Im thinking about a 13.7 inch barrel with the same brake; this would give me an OAL of 16.4. Thats more desirable to me. Is the shorter length worth the lost velocity? Will it be just as accurate out to 200 yards as a 14.5 or 16 inch barrel? That is a question only you can really answer based on what your needs/wants are, but if it were me I'd go for as short as I could (16.1" assuming a non SBR). It will definitely be just as accurate, all other things being equal. https://www.rainierarms.com/?page=shop/detail&product_id=3536 With this: http://www.surefire.com/sfmb-556-1-2-28.html On a Mega billet build. The combo above will give me 16.4 inches.
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Is that the same crowd that says XM193 bounces off heavy clothing? Quoted:
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Define performance Sure its going to have less velocity. Its still plenty lethal. Lots of bad guys have been dropped overseas with 10.3" guns and FMJ rounds don't tell that to the "data" crowd, its impossible for M855 to do anything but icepick past 75 yards according to the "data" Is that the same crowd that says XM193 bounces off heavy clothing? trust me it does, I knew a guy who.................. 
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Here is a graph that was from data during a barrel length study using M855; conducted by Philip H. Dater, MD of GEMTECH and Jason M. Wong of Firearms Law Group.
Effects of Barrel Length on Bore Pressure, Projectile Velocity, and Sound Measurement Barrel Length Studies in 5.56mm NATO Weapons |
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trust me it does, I knew a guy who.................. Quoted:
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Define performance Sure its going to have less velocity. Its still plenty lethal. Lots of bad guys have been dropped overseas with 10.3" guns and FMJ rounds don't tell that to the "data" crowd, its impossible for M855 to do anything but icepick past 75 yards according to the "data" Is that the same crowd that says XM193 bounces off heavy clothing? trust me it does, I knew a guy who.................. My brother-IL's cousins sisters aunt had a XM193 bounce off her wool coat once..........
OP yes you will loose velocity with a shorter barrel how much well that depends on the load you are shooting, the barrel length, the rifling, the twist, the atmospheric conditions (temp humidity elevation etc).... How much probably not a significant amount from 16-14.5 that you will ever notice..... 10-20 yes velocity will be different much more so but still not huge amounts that you will suffer in the performance area especially if you tailor your loads to your rifles. |
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Here is a graph that was from data during a barrel length study using M855; conducted by Philip H. Dater, MD of GEMTECH and Jason M. Wong of Firearms Law Group. http://sadefensejournal.com/wp/wp-content/uploads/2012/02/barrel6.jpg Effects of Barrel Length on Bore Pressure, Projectile Velocity, and Sound Measurement Barrel Length Studies in 5.56mm NATO Weapons There is another graph similiar to this which caused me to go with a 11.5" barrel vs 10.5" on my pistol. As far as the OP goes make sure you measurements are correct, the length of the brake attached to you rifle is non the OAL of the brake, you have to subtract off the threads since they overlap. I recently went from a 16" barreled upper to a 14.7" with an A2 bringing it to 16.1" and I could not be happier you definitely notice the reduced length, also I went from a medium profile Hbar under the hand guards to light weight which made it significantly lighter. http://www.ar15.com/archive/topic.html?b=6&f=20&t=397749 From the measurement on this thread, it looks like the length of the muzzle brake attached is only about 2" which means you need a 14.5" barrel unless you plan to SBR, or have one cut to exactly 14" crowned and rethreaded. To be safe I would honestly get a 14.5" barrel, it might be a little over 16" but you probably won't notice 1/2" |
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