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Posted: 9/22/2003 1:56:06 AM EDT
[Last Edit: 9/23/2003 11:22:58 PM EDT by bravo2]
Curoius, Is the m4 barrel in 1/9 twist with 55gr more accurate than the 1/7 m4 barrel. Everythng i read and heard says yes,stability. Now i here these RRA barrels are real accurate and some of these dpms are too. I really want to get opinoins from owners who have RRA m4 barrels in 1/9 and 1/7, also colt m4 in 1/7 vs. like BM 1/7 and DPMS 1/9. Its seems the 1/7 is just a fade cause us gov. uses it on there m4's. Other than the stapability you read about over the yrs i would like hear honest first hand accounts from those who own or have owned most of these barrels. I know some of you own a lot of uppers or ar15 rifles, so tell me what you think on brand and twist preferance.
Link Posted: 9/22/2003 2:20:40 AM EDT
The 1:7 is for 69+ grain loads. For 55grain like you mention, 1:9 is ideal. I shoot 55gr and 62gr mostly. All my upper assemblies are 1:9. Cheers, H
Link Posted: 9/22/2003 3:28:38 AM EDT
Have several, the RRA 1/9 M4, Colt 1/9 M4 and DPMS 1/7 M4, all are 16" bbls. As stated above 1/7 is best for heavier weighted bullets, especially if your intended use is the new Nosler 77 OTM. If your intended use is M193 or M855 the 1/9 RRA is a good choice as it shoots a wide variety of rounds fairly well.
Its seems the 1/7 is just a fade cause us gov. uses it on there m4's.
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It's not a [red]fad[/red], as the US military has specific reasons for use of the 1/7 twists in its' rifles. Just outta curiosity, what the heck is "stapability"? I'm guessing your referring to "bullet stability" as it relates to twist rates, but a bit unsure. Mike
Link Posted: 9/22/2003 8:55:23 AM EDT
RRA M4 barrels only come 1/9. Only Colt, Bushmaster, and the special DPMS barrels are available in 1/7. The 1/7 is not a fad, but the new standard, and soon all the manufacturer's will be offering them, just as they no longer offer 1/12. Much to read; [url]ammo-oracle.com[/url]
Link Posted: 9/22/2003 9:11:45 AM EDT
My most accurate Brl for shooting M193 is an old Colt 1:12 SP1 Brl. The 1:7 is the only twist you should even consider buying at this point. The 75Gn OTM, 77Gn SMK and 100Gn Mag-lenth loads are the most effective loads in the caliber, and you need a 1:7 to fully stabilized them.
Link Posted: 9/22/2003 9:25:40 AM EDT
i posted some info similar to this on another thread about dissy barrels, [url]http://www.ar15.com/forums/topic.html?b=3&f=12&t=170614[/url] but i have found the 1/7 colt M4 barrles to be every bit as accurate out to 200 yards as my colt and bushy 20" A2 barrels and that is shooting 55gr ball ammo. the only strange thing that has happened with the 1/7 barrels is a key hole shot on paper one time, i was using 55gr PMC ammo and shooting at 50 yards sighting a scope. i always thought accuracy was due to how well the barrel was manufactured but i am no expert and YMMV. scott
Link Posted: 9/22/2003 9:47:18 AM EDT
When I purchased a new upper I went with a 1/7 for many of the reasons that have been already mentioned. My old upper has a 1/9 and I did not notice an accuraccy loss with 55gr ammo with my new 1/7 upper. One thing I've noticed is that it seems the 1/7 will work just a well as the 1/9 for the lighter loads but not many 1/9 barrels will work well with the heavier loads. At this time the only other twist rate I'd consider is a 1/8, but only if I were setting up a SPR or other super accurate tack driver. As always YMMV...
Link Posted: 9/22/2003 10:03:47 AM EDT
Does the 1/7 twist allow you to shoot 40 grain Blitzkings and hollowpoints? I think the Ammo Oracle says it won't let you shoot light hunting bullets? Is this true? Thanks CRC
Link Posted: 9/22/2003 11:27:48 AM EDT
Originally Posted By CRC: Does the 1/7 twist allow you to shoot 40 grain Blitzkings and hollowpoints? CRC
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While I can't say for the 40 grainers, here I shot the Walmart Winchester 45 grn. HPs through one of the DPMS 1/7 M4 uppers: [url]http://www.ar15.com/forums/topic.html?b=3&f=118&t=162330&w=searchPop[/url], as well as numerous other rounds. Mike
Link Posted: 9/22/2003 11:57:44 AM EDT
[Last Edit: 9/23/2003 11:20:47 PM EDT by bravo2]
I meant with the term fad was that on our part,most of us like to have military copies or identicals. I too wanted a 1/7 just because it is the original m4 setup. I'm wondering if its worth the effort to trade a 1/9 m4 setup i got to get a asa 9mm upper w/block and 2 uzi mags,and get a 1/7 twist or evan a 1/9 in different brand barrel, mine is a BM now and i had the brake taken off and a KKF put on, still not got to test accuracy of it verses the 16" HB BM i had. I see RRA and wilson and DPMs on the boards which i hear from some that they are getting ones that shoot real good.
Link Posted: 9/22/2003 12:51:41 PM EDT
Before I bought my upper I was very set on 1/9 twist after reading the ammo-oracle and all that. I sure am glad I waited because as time passed and I learned more, I decided on a 1/7 twist. I love it and I won't even consider anything less than 1/8 in ANY of my future upper purchases. As for accuracy (16" barrel).. I shot 0.6" groups from 50 yards with irons and plain old military-quality Q3131A. I don't know how I stack up against other shooters, I'd imagine I'm pretty good but there are MANY more out there much better than me.
Link Posted: 9/22/2003 1:29:45 PM EDT
When I was putting together my rifle I bought a 1/9 Bushmaster M4 barrel and after reading about the 75 and 77 grain ammo I sold it and bought a 1/7 twist Bushmaster M4 barrel. I lost money but dont regret it one bit.
Link Posted: 9/22/2003 5:11:56 PM EDT
[}:D]'s advocate here: -1/7 barrels shooting 55/62 grain ammo are reputed to suffer from premature throat erosion. If you really do not plan on forking out $0.60 a round, your barrel might last longer if you stick with 1/9. -Forest's recent test of the 77 grain Nosler round indicates that 1/9 stabilizes the round well enough, and certainly good enough for self-defense ranges.
Link Posted: 9/22/2003 7:23:30 PM EDT
[Last Edit: 9/22/2003 7:23:55 PM EDT by Hoplophile]
Originally Posted By imposter: [}:D]'s advocate here: -1/7 barrels shooting 55/62 grain ammo are reputed to suffer from premature throat erosion. If you really do not plan on forking out $0.60 a round, your barrel might last longer if you stick with 1/9.
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Full auto weapons have had problems with burning out the barrels, hence the heavier M4 barrel to better handle the heat. You're not going to burn out a 1/7 barrel any faster than a 1/9 if you're shooting semi auto.
-Forest's recent test of the 77 grain Nosler round indicates that 1/9 stabilizes the round well enough, and certainly good enough for self-defense ranges.
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Forest's test showed that 77grain was stabilized well enough in Forest's barrel. Others have reported keyholing when firing 77gr from a 1/9 barrel. The problem is that when a barrel is marked "1/9" it really means "slower than 1/8 and faster than 1/10". The only way to know the actual twist rate of a specific barrel is to measure it with a rod and a lead slug. With a 1/7 barrel you can be sure that it'll handle the 77gr bullets.
Link Posted: 9/22/2003 7:31:53 PM EDT
[Last Edit: 9/22/2003 7:33:46 PM EDT by imposter]
Originally Posted By Hoplophile: You're not going to burn out a 1/7 barrel any faster than a 1/9 if you're shooting semi auto.
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There does seem to be some dispute about this. I don't pretend to know the answer.
Forest's test showed that 77grain was stabilized well enough in Forest's barrel. Others have reported keyholing when firing 77gr from a 1/9 barrel. The problem is that when a barrel is marked "1/9" it really means "slower than 1/8 and faster than 1/10". The only way to know the actual twist rate of a specific barrel is to measure it with a rod and a lead slug. With a 1/7 barrel you can be sure that it'll handle the 77gr bullets.
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I wonder how much of the difference can be accounted for by different elevations and temperatures. That can have a pretty significant impact on the rate of twise reqruired to stabilize a bullet.
Link Posted: 9/22/2003 9:35:10 PM EDT
Originally Posted By imposter: I wonder how much of the difference can be accounted for by different elevations and temperatures. That can have a pretty significant impact on the rate of twise reqruired to stabilize a bullet.
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That's a very good point, and yet another reason that the additional margin of safety from a 1/7 is a very good thing to have if you're going to use 77gr ammo.
Link Posted: 9/22/2003 10:47:03 PM EDT
B2, I know the message content is what's important but your spelling is killing me over here. P.S. I am glad many of my barrels are 1/7. The trend is going back to the faster twist. 1/8 is a nice compromise, and with my 55gr beater rifle, I will happily keep with the 1/9 till they stop making cheap 55gr ammo.
Link Posted: 9/24/2003 12:51:47 PM EDT
Originally Posted By imposter: [}:D]'s advocate here: -Forest's recent test of the 77 grain Nosler round indicates that 1/9 stabilizes the round well enough, and certainly good enough for self-defense ranges.
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Ferrest's test only showed that His brl stabilized the 77Gn SMK on that day. Your 1:9 Brl may be different. An elevation, temputure, or humidity change may result in even Forrest 1:9 rifle not stabilizing the load.
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