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9/22/2017 12:11:25 AM
Posted: 8/9/2005 5:46:43 PM EDT
[Last Edit: 8/9/2005 5:49:10 PM EDT by nutbad]
Is this issue related to the lenght of the barrel or just in the bullet weight. I have read from so many resource that 1:9 is the all around twist fro 55 to 69 grain bullets. In a shorter barrel, do the faster rifling works like 1:7 or these thing are just shooting 77-88 grain bullets. Is it also true the the faster twist stress out the velocity?
Link Posted: 8/10/2005 5:57:27 AM EDT
http://www.ak47.net/forums/topic.html?b=3&f=118&t=242568
Link Posted: 8/10/2005 8:01:09 AM EDT
after reading the thread here's what I understand.

1. what the military uses is somewhat in for the average joe, thus 1:7 is the way to go
2. comflicting info on range effectiveness of shorter barrel 14.5 and shorter in 600 yards thus using a heavier bullets does not really fix the problem.
3. Some says that 1:7 is the average twist for all around weight from 52-77 grain


-what i found from highpower shooter information that bullet weight is the proper way in barrel twist selection:

1:7 is for 81 & heavier
1:8 is for 69 - 80
1:9 is for 59 - 68
1:10 is for 49 - 58
1:12 is for lighter - 48

Therefore the best barrel rate twist is relative to bullet weights. The all around barrel twist should lay on the middle of the scale, leaning on either end would increase or decrease performance.



Link Posted: 8/10/2005 11:57:52 AM EDT
[Last Edit: 8/10/2005 11:58:09 AM EDT by DevL]

Originally Posted By nutbad:
after reading the thread here's what I understand.

1. what the military uses is somewhat in for the average joe, thus 1:7 is the way to go
2. comflicting info on range effectiveness of shorter barrel 14.5 and shorter in 600 yards thus using a heavier bullets does not really fix the problem.
3. Some says that 1:7 is the average twist for all around weight from 52-77 grain


-what i found from highpower shooter information that bullet weight is the proper way in barrel twist selection:

1:7 is for 81 & heavier
1:8 is for 69 - 80
1:9 is for 59 - 68
1:10 is for 49 - 58
1:12 is for lighter - 48

Therefore the best barrel rate twist is relative to bullet weights. The all around barrel twist should lay on the middle of the scale, leaning on either end would increase or decrease performance.






It has nothing to do with bullet weight but instead bullet length and also velocity is a huge factor. Slower bullets like subsonic require faster twists because for a given twist the higher the velocity the higher the RPMs and barrel length also has an effect on velocity.

For a .223 the best accuracy and terminal ballistics come from 75 and 77 grain ammo. The cheapest and best plinking ammo is 55 grain. 1/7 shoots both of these well from a carbine barrel.
Link Posted: 8/11/2005 11:35:10 AM EDT
Why does everyone always pick 1:7 for the "average joe" who will mostly only ever shoot 50-62gr bullets? Even ammo-oracle agrees that 1:9 is probably optimal for those weights/lengths. The 1:7 used on militaary rifles is to stablize the really long tracer rounds.

I say 1:9 for the plinker. Faster twist rates will result in faster barrel wear.

-Stooxie
Link Posted: 8/11/2005 2:15:48 PM EDT
Have you worn out a 1/7 barrel?

The only "advantage" of 1/9 is that it allows you to shoot light varmint rounds.

If you don't have a varmint rifle, who cares? Heavy bullets are better for everything else.

1/7 will handle 55 and 62 grain bullets just fine.

Go with 1/7.
Link Posted: 8/11/2005 3:49:20 PM EDT
Since I don't see anybody here going to war tomorrow with their personal AR. Go with the 1/9. The paper/pop cans/Ivans/pumkins/tannerites will not know the difference.

To heck with the "heavy round" theory, I don't plan on ever buying anything heaver than 62 and my 1/9 barrel likes that just fine.

Hey Ivan, do you know what twist barrel I turned you into swiss cheese with?

No, I did'nt think you knew....

Carry on... make up your own mind.
Link Posted: 8/11/2005 7:47:54 PM EDT
I'de say i'll go with the 1/9 for my 14.5" and 1/8 for my 20 , then the future project 1/7 is for 18" that would complete my selection.

14.5" serves as my racegun in really close flat shooting within 150 yards

20" as my DCM rifle that would reach 600 yards nice and easy

18" I still can't figure out how this build can serve my shooting sports

In a local 250 hits 3gun matches, the average target placed beyond 100 yards are probably 30 hits and most were on the 7-50 yards range. For really close, shooting light and fast bullets are my choice, this is because the rifle in being lightly shouldered during fast swing from target to target and shooting double taps. My choices were now clear.

Link Posted: 8/12/2005 7:53:20 AM EDT
tag
Link Posted: 8/12/2005 8:26:59 AM EDT
I heard somewhere that 1/7 won't stabilize a 90grain bullet.

Is that true?

Anyone shoot 90's from a 1/7?

What max range have you shot to that they are still stabilized at?

The article I was reading was suggesting 1/6.5 inch twist for the 90SMK's
Link Posted: 8/12/2005 9:59:41 AM EDT
John Holliger has said that the 90 gr SMKs are stabilized out of his 1/7 DCM barrels.
I would tend to believe him, as he isn't known for bsing.

I haven't gotten around to tryin them yet tho.
Link Posted: 8/12/2005 5:29:28 PM EDT
I read most 1/9s can stablize 75/77 rounds
Link Posted: 8/12/2005 5:46:37 PM EDT
I have both 1/7 and 1/9 barrels in my collection and like them both. My defensive weapons tend to have 1/7 barrels because 75gr TAP is my defensive round of choice. While 75gr rounds may or may not work in a 1/9 barrel, they will work properly for sure in a 1/7-hence my choice.

Link Posted: 8/12/2005 8:45:07 PM EDT
as i dig more deeper on this i came accross the RRA Goverment Model aka DEA issued carbine. this was in the Guns and Ammo March 2005 issue in the proof house article page 40. It was stated that this carbine carry a 1/9 twist for versatility of loads from 40 gr VMAX to 75 gr Hornandy Match.

Link Posted: 8/12/2005 8:48:33 PM EDT

Originally Posted By CB1:
Since I don't see anybody here going to war tomorrow with their personal AR.



Are you sure of that sir?

Some of us here might question that response. Call Wes @ MSTN to see how many of us are @WAR with our own hardware.
Link Posted: 8/13/2005 4:26:55 AM EDT

Originally Posted By IndOperator1:

Originally Posted By CB1:
Since I don't see anybody here going to war tomorrow with their personal AR.



Are you sure of that sir?

Some of us here might question that response. Call Wes @ MSTN to see how many of us are @WAR with our own hardware.



Stop it... I am aware of Professionals that use their ARs in Harms Way and I Salute them in the highest degree.

I am talking about all the ArmChair Commandos who think they need everything the Professionals need
(Professionals include Military and Security Contractors)
Link Posted: 8/13/2005 6:47:22 AM EDT
Rifling… Bushmaster barrels are button rifled with 6 grooves and lands (right hand twist, 1 turn in 9", except for DCM barrels - 1 in 8"). Our experience is that the 1 in 9" twist offers the best results with the widest variety of ammunition. Most barrels are heavy profile their full length - to help alleviate barrel whip and inaccuracy in rapid or full-auto fire.

http://www.bushmaster.com/shopping/barrel-assemblies/

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