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Posted: 10/29/2006 7:32:29 AM EDT
[#1]
Anything less than 10.5" cannot be counted on to generate enough velocity to create fragmentation with any known standard 5.56/.223 round.
11.5" is considered the bare minimum. 1:7" twist rate on short bbls. is strongly suggested. A 7.x" bbl. with Frangible, or possibly 62gr. Soft Point ammo. may deliver a significant-enough wound to justify its usage, but will not generate enough velocity at any point in the round's trajectory to fragment a normal round. I use 62gr. SPs and Frangibles in my 7.3" 1:7" twist pistol. I use 62gr. SPs, Frangibles, and 75gr. BTHP (TAP) in my 11.5" 1:7" twist CQB pistol upper My carbine, not really constrained by such velocity issues, uses whatever, though heavy is better with anything. Hope that helps. |
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Posted: 10/29/2006 7:58:56 AM EDT
[#2]
I assume you can put any length barrel on a pistol as long as you dont put a stock on with a barrel under 16". Is that correct?
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Posted: 10/29/2006 8:01:59 AM EDT
[#3]
Yes sir, any length. You can even go over 16" if you want to.
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Posted: 11/1/2006 10:05:25 AM EDT
[#4]
Which does not matter to 99% of the people on this website because most people here are not shooting at other people. Get whatever length you want, UNLESS you intend to be shooting at Hadji. Then, get a 308. |
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Posted: 11/1/2006 10:54:32 AM EDT
[#5]
+1
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Posted: 11/1/2006 11:02:36 AM EDT
[#6]
So, I'm not supposed to mention that information, is that what you are telling me, sir? |
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Posted: 11/1/2006 11:21:00 AM EDT
[#7]
Its not a .308, but I also have a 7.65x39 upper and was considering buying another and shortening the barrel since it is cheaper to buy a long barrel than a short one, and they are in greater supply.
I assume that I can cut a barrel to any length I want as long as I dont put a butt stock on the pistol lower with a barrel shorter than 16". Thanks! |
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Posted: 11/2/2006 12:10:55 AM EDT
[#8]
Not saying that at all. Just keep it in context. Example: Fragmentation range will not matter on cardboard, paper or steel targets If you need to shoot at 2 legged targets, then you need to consider fragmentation range. A 10.5" barrel with xxx ammo will only be good out to xxx yards. An 11.5" barrel with xxx ammo will get you an extra xx yards. |
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Posted: 11/2/2006 12:22:36 AM EDT
[#9]
Don't assume this.  The amount of barrel PAST the gas port is very important. In a 7.62x39 AR, the length is MORE CRITICAL than in a 5.56x45 AR due to the differences in bore volume expansion and resulting losses of gas pressure. You would be able to shorten the barrel some and open up the port to retain function. You would eventually reach a point where you can't open up the port enough to get proper function. Hard to say where this point is without testing. If you wanted to cut the barrel back an inch at a time and open up the port for proper function, I would stop when you reach a barrel length where a 0.110" gas port will just keep the action running. Going to a shorter with a bigger port than this is asking for trouble. |
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Posted: 11/2/2006 5:02:26 AM EDT
[#10]
I have seen a 7.62x39 11.5" Model 1 upper at a gun show and the front sight is the same distance as the 16" barrel. I dont know if the gas port was opened, but the port distance had not been shortened. I dont mind cut and try.
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Posted: 11/2/2006 5:57:45 AM EDT
[#11]
That was a pistol gas system barrel. If the distance from gas port to muzzle was the same as a 16" barrel, the port would actually be a little smaller as the starting gas pressure is higher at pistol length than at carbine length. |
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Posted: 11/2/2006 7:23:35 AM EDT
[#12]
Sorry I was not clear on my description. The gas port is the same distance from the breach end, not the muzzle end. Unless there was a gas port under the handguard separate from the front sight that was closer to the breach.
How is a pistol gas system configured for a 11.5" barrel? |
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Posted: 11/2/2006 9:27:18 AM EDT
[#13]
I have never done a pistol length gas system on a 7.62x39 barrel, but here is my gas systems page that will visually show how long the different gas systems are. |
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Posted: 11/2/2006 9:32:58 AM EDT
[#14]
These people will know.
They helped me build my 8" 5.45x39 pistol, before I came over to the Dark Side. Check them out. I'll cross-post there so they'll be expecting you. Best to you, -Kyrinn |
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