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Barrel Lengths, Rifle Design |
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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18-20" and 178 - 200 gr with reasonably high BC (above .450 or so) is GTG, but I thought we already answered the barrel part. You're not going to get a consensus answer, though; opinions vary. |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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338LAPUASLAP
Optics Master Scope Swapper Joined: October/17/2009 Status: Offline Points: 2596 |
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Wow and you wonder why people leave before they can get a good answer.
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No one
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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... bullet weights given your Sig Sauer 716 PM reference, which tells me you're interested in 7.62 rather than 5.56.
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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cheaptrick
MODERATOR Joined: September/27/2004 Location: South Carolina Status: Offline Points: 20844 |
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If at first you don't secede...try..try again.
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RifleDude
MODERATOR EVIL OPPRESSOR Joined: October/13/2006 Location: Texas Status: Offline Points: 16337 |
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Why? You got answers to all your questions, and during the time we got off-topic, we were posting simultaneously before we had a chance to read your follow-up comments. For my part, I apologize for helping steer the thread off-topic, however you did ask about barrel length considerations AND rifle design, and gas system length and type is directly related to both. |
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Ted
Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle. |
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338LAPUASLAP
Optics Master Scope Swapper Joined: October/17/2009 Status: Offline Points: 2596 |
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That is the shortest tower I have ever seen.
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No one
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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And I recall the slats being MUCH further apart.
On the barrel length, sorry, I missed that it was a 716, so we are talking 308 and not 223. In which case, I would say 600 yards is OK, 800 is pushing it, depending on exactly what is expected. It is not a precision rifle and should not be counted on to function as one. With a 16" tube, expect most ammo (LR118, Balck Hills 168 SMK, and the like) to exit the barrel in the ballpark of 2500, give or take (LOTS of variables.) Does that help. |
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Freedom is something you take.
Respect is something you earn. Equality is something you whine about not being given. |
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338LAPUASLAP
Optics Master Scope Swapper Joined: October/17/2009 Status: Offline Points: 2596 |
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5ft I remember 50ft basic 80ft selection maybe 75ft.
I pm'd the OP and I believe he has enough info. Keep HJ'ing this thread. It will keep up my entertainment value. |
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No one
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gulf1263
Optics Apprentice Joined: June/15/2011 Location: Alaska Status: Offline Points: 212 |
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IMHO, 5.56 mm barrel length has to do with mission.
Shorter barrels are handy, especially in the semi-auto formats if they are to be used for combative type missions..i.e door kicking, room clearing, etc.. For varmitting use, a 20 inch barrel gives more velocity, allowing the bullets to open up at longer ranges. Piston guns are not necessary until you get into the really shorter barrels, say 11.5 inches and shorter, especially in full auto. I run an 18 inch full auto, FNC piston gun but in truth would have been happy with a GI M-4 with a 14.5 inch, even though I don't kick doors for a living anymore. For a bolt gun, a 22 inch barrel gives a little extra zing but in a heavy barrel a 20 inch shoots fine. I think a lot of folks buy something other than an M-4 for the Chicks Dig It factor, rather than a real need. You can get away with a cheaper gun that you won't run hard versus one that your life will depend on and that you train weekly with. A hobby gun is fine to bring out to the range and play with. I saw a S&W MP-15 for $775.00 recently, shoot it until you wear out the barrel, upper receiver and several bolts, then stick a BCM upper on it and shoot it some more. The lower will last quite a long time. A friend puts about 300 rounds a year on his Eagle carbine built in the early eighties and it is fine. Art |
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Good day.
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BeltFed
Optics Retard Joined: February/12/2008 Location: Ky Status: Offline Points: 22287 |
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Gosh, I was going to weigh in on the OP's original question, concerning sight radius, and open sights vs CQB rifles with optics, etc, etc.
I like bullpups, you can get a 20" barrel for the same package as a CAR 15 with a 16" barrel and a collapsed stock. However, many countries that use the AUG choose 16" barrels for general issue.
Speaking of pistons, the Styer AUG uses a short stroke piston which is attached to the barrel, so if you change barrels from one length to another, you have the correct size gas port.
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Life's concerns should be about the 120lb pack your trying to get to the top of the mountain, and not the rock in your boot.
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PPD7800
Optics GrassHopper Joined: June/11/2012 Location: Arizona Status: Offline Points: 10 |
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ok ref. BBL length here is some results that a smith found out.
BBL Length vs. Velocity This is from well known maker Charlie Sisk: All these were Shilen barrels. I used the same brass through out the whole test. All weighed to with 1 grain. Bullets were tested on the Juenke machine. Powder charges were weighed to .1 grain. The same rest, chronograph, 22-250 Hodgdon 380 34 grains Federal GM210M Remington brass 55 grain Ballistic Tip 27” 3469 fps 26” 3451 25” 3425 24” 3407 56 fps spread from highest to lowest 270 Winchester Hodgdon 4350 54 grains Federal GM210M Winchester brass 130 grain Sierra 27” 3115 fps 26” 3093 25” 3071 24” 3054 23” 3035 22” 3027 21” 3001 114 fps spread from highest to lowest 300 Winchester mag Federal GM215M Winchester brass 74 grains of Reloder 22 180 grain Partition 27” 3055 fps 26” 3031 25” 3024 24” 3003 23” 2984 22” 2960 95 fps spread from highest to lowest 340 Weatherby Federal GM215M 250 grain Sierra 81 grains Reloder 22 Wby brass 27” 2837 fps 26” 2817 25” 2809 24” 2791 23” 2777 22” 2755 21” 2731 106 fps spread from highest to lowest |
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"The sheep pretend the wolf will never come, but the sheepdog lives for that day."
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338LAPUASLAP
Optics Master Scope Swapper Joined: October/17/2009 Status: Offline Points: 2596 |
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rule o thumb 20-30fps per inch...
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No one
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Rancid Coolaid
MODERATOR Joined: January/19/2005 Location: United States Status: Offline Points: 9318 |
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Less with a custom barrel or polygonal barrel, more for a factory barrel.
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Freedom is something you take.
Respect is something you earn. Equality is something you whine about not being given. |
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