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Maybe you should just be clear with your statements.
Are you of the opinion that 1:9 twist is the best solution for the commercial AR, and that 1:7 is simply the realm of internet wannabes? Because that's the impression you're giving, whether you mean to or not. If that's your opinion then just come out and state it, but it's the reason you're getting the kind of replies you're getting.
I'd also be curious to know what you own yourself, as threads like this (and posts like yours) are most often colored by personal possessions and emotional attachment to them and the knowledgebase and decision-making process that went into purchasing them.
Clearly we're not communicating, because that's exactly the impression I'm getting from the "dealbreaker crowd."
Perhaps it's just the language that I disagree with. It makes me picture some wannabe giving your weapon the thumbs down because it isn't sporting the latest and greatest gadget, or it's configuration doesn't reflect the opinions of some "authority."
Contrary to what we may be lead to believe on the internet, Mk. 262 is not a revolutionary, game changing, "OMG, how have we been so wrong for so long" innovation. I'm sure you will not disagree that every round has it's own set of characeristics. I had to re-acquaint myself with Gary Roberts report after reading the above, b/c when I think of "Dr. Roberts," the first thing I think of is "Barrier Blind" and 6.8x43mm... not 77 gr. superiority.
I pulled this up on DTIC, and you can even check out slide 11 of his presentation depicting 62 grain bonded FBI outperforming 77 grain SMK.
http://www.dtic.mil/ndia/2008Intl/Roberts.pdf
I think the "dealbreaker" crowd should review this before making the bold assertion that "Good Ammo = 75 or 77 grain" which obviously necessitates 1/7.
I have a 1/9 Stag 16" and a 1/9 LaRue build with 11.5" Bushmaster barrel. My Noveske is of course a 1/7. I shoot primarily M193, but I've put M855 through both the Stag and the SBR with no ill effects on accuracy or stabilization. Whether that is due to the twist being closer to 1/8" or just luck, I don't know.
I'm comfortable with holding the minority opinion on this one.
I think it would be helpful if Doc weighed in, since so many are using his words & research to back up their own claims.
I initially posted in this thread that 1:9, considered in a vacuum, wouldn't be a "deal breaker" for me. However, you cannot consider these things in a vacuum. As others have posted, you're going to be very hard pressed to find a firearm of the same quality features as one that comes with a 1:7 but is in a 1:9. I don't know of many, if any, AR carbines that are on par with Colt, BCM, LMT, DD, and Noveske that also come with 1:9 outside of perhaps the Colt Commercial guns and even then you wind up with issues like HBAR profiles, target crown/compensators, and potentially fixed stocks (anyone know for sure if they're still pinning the stocks? I assume so since these guns are intended for ban states now).
Even when factoring in budget many of us have posted in other threads until our fingers bleed that most of your "budget" guns really aren't when you consider what they are lacking (ignoring the barrel twist) and the actual prices of the better quality firearms if you shop smart.
So, while a 1:9 wouldn't be a deal breaker for me, I see absolutely no reason why I'd ever wind up with one in my safe.
Yes, clearly there is a communication error as I still don't understand your point. Are you only taking the contrarian opinion because you don't like the absolutism of some of the posters on the other side?
Let's revert a bit. If someone told you they were buying a carbine for general plinking, range use, maybe a class or two, and the potential to use it in a defensive role should the need arise, would you advise them 1:7 or 1:9?
I think the responses of the "dealbreaker/unacceptable" posters reflect an overly emotional segment of our community that's always grasping for the next best thing to overcome their insecurity. I'll bet if the OP does go 1/7 there will be someone there to "thumbs down" his pick b/c it's not cold hammer forged just as there is someone to "thumbs down" that guy's pick b/c it's not cryo'ed.
When you have confidence in your ability and your equipment, you don't have to draw a line in the sand and make the "better" the enemy of the "good."
Damn... is this turning into another thread about your spreadsheet?
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1/7 for total, all around use. Though I say 1/9 per the OPs specs, or if I were restricted to using only M193.
The following superb quotes regarding pistons and barrel twists pretty much sum up what needs to be said:
"They have dubious benefits especially in a carbine length gun. The only time they might be beneficial is if you are:
1. Using a short length gun 10~11"
2. Using a silencer
3. Heavy amounts of rapid fire, like 1000 rounds a day heavy fire
If you cannot answer yes to at least 2 from this list, you do not need a piston"-------------------"It depends on the barrel length and bullets you prefer. It is all about rotational velocity. 1:9 in a 20 inch barrel is not as bad as in a 7.5 inch barrel. I would want 1:6 for a barrel under 9 inches, 1:7 for a barrel 9-20 inches, and 1:8 for a barrel over 20 inches. Even for a long barrel length, I would consider 69 grain to be the max for a 1:9. If you want the capability to shoot 75 and 77 at sea level or in cold weather, then you need 1:7. Is 1:7 significantly worse for 55 grain bullets? I doubt it. I have not seen anyone do a proper comparison test. You could order 10 barrels of 1:7 and 10 in 1:9 have have them made at the same time on the same cut-rifle machine and then compare them with 30 shot groups. That is under 1000 rounds of ammo."
Regarding my NDIA presentation (http://www.dtic.mil/ndia/2008Intl/Roberts.pdf), in addition to the early upset information referenced from page 11, I would direct folks to read pages 6 and 9; in addition, please check the recommendations found here: https://www.m4carbine.net/showthread.php?t=19881. If I were assigned a Mk12 SPR or DMR type rifle with the potential for making shots beyond 300 meters, Mk262 is the perfect ammo choice, as this is what it was designed for. On the other hand, if the primary use for my weapon system is at closer range for LE duty, CQB, or personal defense, then Mk262 would not be one of the ammo loads I would select, as there are better choices available for those roles, as noted.
1/7 twists make the most sense this day and age, as do mid-length DI gas systems. If for some reason I was issued or somehow ended up with a 1/9 twist barrel and carbine gas system, I would not fret--rather I would shoot the snot out of it with whatever cheap training ammo we had around (typically 55 gr FMJ), then change the barrel to a 1/7 middy when appropriate (usually around 10,000-20,000 rounds depending on accuracy and gas port erosion issues).
Last edited by DocGKR; 03-09-10 at 12:19.
Thanks for the post Doc.
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