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TX, USA
Posted: 9/26/2024 3:38:16 PM EDT
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Where can I get a 10.3 or 11.5in upper with a 1/9 twist and an A1 or A2 upper? |
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AZ, USA
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The new guy in town walks into the LGS and asks where he can get a good steak dinner. The old codger sitting by the pot-bellied stoves tells him that what he really should order is a chicken dinner. The clerk then tells them that he prefers fish. The new guy shakes his head and walks into the Walmart across the street where he asks the same question again. That night he enjoyed the best steak dinner he ever ate. . |
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1:8 at the bare minimum, 1:7 better. 1:9 if all you ever want to shoot is 55 grainers. Do a search for A1 and A2 uppers if a classic build is what you want, there are a few places making them, but they're not cheap in most cases. Or, you could buy an A1 or A2 receiver (complete or stripped) and then find the barrel you want and assemble it yourself. Last resort of you want a semi-classic build, PSA has them, but they have the detachable carry handle type, so not really a true A1 or A2 receiver. A couple places to look: https://davidsondefense.com/a2-front-sight-upper-build.html https://www.tntesales.com/c7-uppers-has-shell-deflector/ <-- A1 uppers, couple of them with 11.5" barrel options (pencil and HBAR), $775. |
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Originally Posted By ForwardResist: The new guy in town walks into the LGS and asks where he can get a good steak dinner. The old codger sitting by the pot-bellied stoves tells him that what he really should order is a chicken dinner. The clerk then tells them that he prefers fish. The new guy shakes his head and walks into the Walmart across the street where he asks the same question again. That night he enjoyed the best steak dinner he ever ate. . Except that the discussion isn’t about subjective tastes, it’s about objective mechanics. |
Point shooting will give you monkeypox. - John_Wayne777
The Emu War could have been won if the Australians used red dots on their handguns.
The Emu War could have been won if the Australians used red dots on their handguns.
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Lighten up guys. Not every discussion needs to be a poop slinging fest if somebody likes something outside the accepted “optimum”. It makes us all look like a bunch of opinionated old codgers! OP there is nothing wrong with 1/9 barrels at all. They work great and I prefer them for shooting cheap M193 ammo. That being said they can be harder to find these days. |
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Originally Posted By EDL: 1:9 if all you ever want to shoot is 55 grainers. It may not be tacticool but this is a ridiculous assertion. 1:9 is good for everything up to and including M855, 69gr Sierra OTMs, Berger says their 73gr is ok in a 1:9. The only thing you'd need to be wary of would be 75 & 77gr stuff, and the Hornady 68. Softpoint barrier loads should all be good. |
This is...a clue - Pat_Rogers
I'm not adequately aluminumized for this thread. - gonzo_beyondo
CO, MI, OR - Please lobby your legislators to end discrimination against non-resident CCW permit holders
I'm not adequately aluminumized for this thread. - gonzo_beyondo
CO, MI, OR - Please lobby your legislators to end discrimination against non-resident CCW permit holders
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Originally Posted By Gamma762: It may not be tacticool but this is a ridiculous assertion. 1:9 is good for everything up to and including M855, 69gr Sierra OTMs, Berger says their 73gr is ok in a 1:9. The only thing you'd need to be wary of would be 75 & 77gr stuff, and the Hornady 68. Softpoint barrier loads should all be good. That. |
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Originally Posted By gtsteve03: 1:9 twist is the spec for SS109. Maybe OP has a stockpile of green tips. Out of a barrel that's long enough to give the desired muzzle velocity and thus the desired RPM. The RPM's out of a 10.5" are going to be a decent bit lower. The stability requires RPM, to be stable. While I consider 1/7 to be an oversold twist by far, and tend to prefer 1/8 in most applications - for an SBR in a world where MK262 isn't that rare, 1/7 makes some sense. |
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Originally Posted By lazyengineer: Out of a barrel that's long enough to give the desired muzzle velocity and thus the desired RPM. The RPM's out of a 10.5" are going to be a decent bit lower. The stability requires RPM, to be stable. While I consider 1/7 to be an oversold twist by far, and tend to prefer 1/8 in most applications - for an SBR in a world where MK262 isn't that rare, 1/7 makes some sense. Originally Posted By lazyengineer: Originally Posted By gtsteve03: 1:9 twist is the spec for SS109. Maybe OP has a stockpile of green tips. Out of a barrel that's long enough to give the desired muzzle velocity and thus the desired RPM. The RPM's out of a 10.5" are going to be a decent bit lower. The stability requires RPM, to be stable. While I consider 1/7 to be an oversold twist by far, and tend to prefer 1/8 in most applications - for an SBR in a world where MK262 isn't that rare, 1/7 makes some sense. Reduced muzzle velocity requires less RPM for stability... it's not an exact match, but reasonably close in practical terms. |
This is...a clue - Pat_Rogers
I'm not adequately aluminumized for this thread. - gonzo_beyondo
CO, MI, OR - Please lobby your legislators to end discrimination against non-resident CCW permit holders
I'm not adequately aluminumized for this thread. - gonzo_beyondo
CO, MI, OR - Please lobby your legislators to end discrimination against non-resident CCW permit holders
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No 12 twist?!? |
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Originally Posted By Gamma762: Reduced muzzle velocity requires less RPM for stability... it's not an exact match, but reasonably close in practical terms. Originally Posted By Gamma762: Originally Posted By lazyengineer: Originally Posted By gtsteve03: 1:9 twist is the spec for SS109. Maybe OP has a stockpile of green tips. Out of a barrel that's long enough to give the desired muzzle velocity and thus the desired RPM. The RPM's out of a 10.5" are going to be a decent bit lower. The stability requires RPM, to be stable. While I consider 1/7 to be an oversold twist by far, and tend to prefer 1/8 in most applications - for an SBR in a world where MK262 isn't that rare, 1/7 makes some sense. Reduced muzzle velocity requires less RPM for stability... it's not an exact match, but reasonably close in practical terms. Nope. Go run the calculator. The loss of RPM exceeds any benefiits https://bergerbullets.com/twist-rate-calculator/ Take a long marginal bullet and run it 1/9 twist. As you slow down velocity, it loses stability, because it loses RPM's. Shorter barrels need faster twist. |
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