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Posted: 8/20/2006 12:13:36 PM EST
Everywhere you look on these boards you see people shouting the benefits of the 1/7 inch twist barrels.  Yet several manufacturers standard barrel twist is 1/9".  Sooo, back to my original question...why aren't all barrels 1/7" twist?
Link Posted: 8/20/2006 12:18:51 PM EST
[#1]
Becasuse 1/7 is for long tracer bullets.
Link Posted: 8/20/2006 12:20:46 PM EST
[#2]
Cause your average joe is a plinker, so 55 grain ammo is the big seller.
1/7 bbls are specialized tools for a civie, as most people don't ponder what twist rate/bullet weight has the best ballistics.
Link Posted: 8/20/2006 12:23:19 PM EST
[#3]
1/7 is a less compatible twist than 1/9, in that it does not work as well with as many different projectiles.

For the ultimate in heavy-weight tacti-cool rounds, you need a 1/7.  For most everything else 1/9 is a good twist.
Link Posted: 8/20/2006 12:53:09 PM EST
[#4]
I wish they would standardize barrel twists, offering only a 1/7. That way we wouldn't have to deal with the near constant "1/7 vs. 1/9 twist?" threads.
Link Posted: 8/20/2006 12:59:23 PM EST
[#5]
What does the .gov have their rifles in? 1-9 or 1-7?

Link Posted: 8/20/2006 1:08:42 PM EST
[#6]

Quoted:
What does the .gov have their rifles in? 1-9 or 1-7?



1/7
Link Posted: 8/20/2006 1:09:04 PM EST
[#7]
they dont.

me i run 1/12
Link Posted: 8/20/2006 1:19:20 PM EST
[#8]

Quoted:

Quoted:
What does the .gov have their rifles in? 1-9 or 1-7?



1/7


What's the downside to 1/7?

I could have swore the newer FN m16's were 1-9...



Link Posted: 8/20/2006 1:22:35 PM EST
[#9]

Quoted:
they dont.

me i run 1/12

why? do you like shooting light projectiles?
Link Posted: 8/20/2006 1:23:21 PM EST
[#10]
Lighter loads no like 'em.
Link Posted: 8/20/2006 1:28:15 PM EST
[#11]
I don't think it makes that much of a difference really.  My 1:7 shoots tighter groups with the heavier bullets, but it shoots accurate groups with the 55grn as well.  I'd get the 1:7 if it were me.  Yes, it doesn't shoot as tight a group with the lighter stuff, but it's such a small difference that most people won't even notice.
Link Posted: 8/20/2006 1:43:11 PM EST
[#12]
The only reason the military went to 1/7 is like was said at the beginning of the thread the longer tracer rounds.You get more velocity out of 55 grain than say 62 and heavier bullets dont necesarily mean more effective.Like in somalia in 1993...if your shooting people that dont have at least a thickness of 12 or 14 inches the bullet zips right through.Remember the first gulf war back in 90-91 we were using the 55 grain stuff as thats what was in service in big numbers at the time and I dont think the heavier 62 grain was used until late 92 early 93.

The M16 A2 came ut in what 1984 so 55 grain was used in the 1/7 a long time before the switch,I dont even know if the new tracer was being used at the time.I dont think either or is better 1/7 or 1/9 I can use bullet weights of 77 grain out of my 1/9 and its fine.I think bullet legnth and shape determine what twist is better to use.In that reguard I own both a 1/7 and 1/9 barrel.Ballistics mean nothing in an AR if your not hitting vital areas..shot placement is paramount.People come in all shapes and sizes and a 55 grain or 62 grain bullet that might fragment in one person may not in another.
Link Posted: 8/20/2006 1:48:28 PM EST
[#13]
Because most people buy cheap ammo to put through their cheap rifles.
Link Posted: 8/20/2006 2:02:55 PM EST
[#14]

Quoted:

Quoted:
they dont.

me i run 1/12

why? do you like shooting light projectiles?


Probably because it's a retro build.
Link Posted: 8/20/2006 2:09:34 PM EST
[#15]
1:7 is likely just a tad bit more expensive to produce....

And since most AR folks don't shoot the heavy OTMs, most manufacturers see 1:7 as a 'premium' or 'match' option to sell as an upgrade, Market segmentation....

IRL, there's no advantage to a 1:9 unless you shoot very light (sub-50gr) hunting rounds.

For 55 and up, 1-7 works fine.....
Link Posted: 8/20/2006 2:22:22 PM EST
[#16]
Dang, seen all kinds of cheap talk on this subject.

1:7 is needed to get the heavy bullets spun up fast enough so that they stabalize. If the bullet is not stable then your balistics goes to hell and you aint going to hit anyone out past 200 yrds. And I prefer to shoot someone whom is 300 yrds away than to let them get within 100 yrds where he might be able to hit the broad side of a barn.

But at the same time 1:7 might be to fast for a light bullet. this would also inclue say a hollow point. Or a pre fragmented bullet.

Now in my opinion, the 1:9 twist is just about right. And I dont want to even talk about the old 1:12 twist which is only good for 50 grain and down.

In short, you need to spin up them heavy bullets or have them tumbling down range all over the place. But then too, a light weight bullet or a pre frag bullet can be over spun and watch it become lead dust about 20 yrds in front of you. Hence the reason to pick your twist to the type of bullet you plan to shoot.

Link Posted: 8/20/2006 2:45:18 PM EST
[#17]

Quoted:
Now in my opinion, the 1:9 twist is just about right. And I dont want to even talk about the old 1:12 twist which is only good for 50 grain and down.

In short, you need to spin up them heavy bullets or have them tumbling down range all over the place. But then too, a light weight bullet or a pre frag bullet can be over spun and watch it become lead dust about 20 yrds in front of you. Hence the reason to pick your twist to the type of bullet you plan to shoot.



I was at the range yesterday shooting my 1:9 RRA. Another guy down the line was trying to sight in a NEF Handi Rifle in .223 -- which I believe is 1:12. He was getting keyholes at 50 yards. We got to talking and he said he was using 62g Green Tip. I gave him a few rounds of my 55g XM193 and that cured the tumbling problem.

While this doesn't address the 1:7 question it does point out that you have to match the ammo to the barrel.

As I understand it:

the slow barrels (1:12 and 1:14) are primarily for light, varmint type rounds in the 40-50g range. A lot of your hunting style rifles have these slow barrels (Remington 700 is 1:12 I believe).

medium twist barrels (1:9/1:10) are the generalists. They'll shoot the medium weight/size stuff just fine and MAY handle the lighter stuff reasonably well, too. I believe most of your non-Colt AR-style rifles are 1:9. A few of your hunting rifles (Savage, for one) have 1:9 barrels. I belive the "tacticool" rifles (i.e. sniper) rifles are also 1:9.

fast barrels (1:7) are for shootin the heavy match bullets and the LONG bullets, like the military tracer round. Unless you're going to shoot these rounds there really is no reason to go with 1:7

The point of all this is that you really need to consider what ammo you're going to be shooting when you pick out a .223/5.56 gun. Otherwise, if you've already got the gun you need to choose your ammo with your twist rate in mind.

Link Posted: 8/20/2006 2:51:34 PM EST
[#18]

Quoted:
Because most people buy cheap ammo to put through their cheap rifles.




Is there a [whackoff] smiley?
Link Posted: 8/20/2006 2:51:34 PM EST
[#19]

Quoted:
Dang, seen all kinds of cheap talk on this subject.

1:7 is needed to get the heavy bullets spun up fast enough so that they stabalize. If the bullet is not stable then your balistics goes to hell and you aint going to hit anyone out past 200 yrds. And I prefer to shoot someone whom is 300 yrds away than to let them get within 100 yrds where he might be able to hit the broad side of a barn.

But at the same time 1:7 might be to fast for a light bullet. this would also inclue say a hollow point. Or a pre fragmented bullet.

Now in my opinion, the 1:9 twist is just about right. And I dont want to even talk about the old 1:12 twist which is only good for 50 grain and down.


In short, you need to spin up them heavy bullets or have them tumbling down range all over the place. But then too, a light weight bullet or a pre frag bullet can be over spun and watch it become lead dust about 20 yrds in front of you. Hence the reason to pick your twist to the type of bullet you plan to shoot.



Umm I might be mistaken but the original m16A1s and SP1s were 1/12 and they shot m193 55 grainers...

Link Posted: 8/20/2006 2:57:06 PM EST
[#20]

Quoted:
1:7 is likely just a tad bit more expensive to produce....

And since most AR folks don't shoot the heavy OTMs, most manufacturers see 1:7 as a 'premium' or 'match' option to sell as an upgrade, Market segmentation....

IRL, there's no advantage to a 1:9 unless you shoot very light (sub-50gr) hunting rounds.

For 55 and up, 1-7 works fine.....


Most "match" barrels I've seen are 1/8.

But if you want to go with the cheaper "military style" 1/7 that's cool too.  Not quite as Elite, but you know...

(Not directed at you, but the suggestion by some that 1/9 is the cheapass bubba twist is just, well, retarded.  It's a general purpose shoots almost everything twist.)
Link Posted: 8/20/2006 3:02:37 PM EST
[#21]
I've seen very fast twist barrels cause lighter projectiles to come apart at higher velocities.

Very high velocities mixed very with fast twists can get projectiles pushing 30,000 RPM.  Even a small .223 projectile has a limit at how fast they'll spin and stay together.  Every projectile is different but there's a point they cannot be pushed past.
Link Posted: 8/20/2006 3:03:10 PM EST
[#22]

Quoted:
Because most people buy cheap ammo to put through their cheap rifles.


Hey....If by cheep, you meen Consistant headshots at 300yds with 55gr 1/9 twist......then hell, that works for me.


ETA. With irons by the way...just got back from the range this morning and feelin pretty good.
Link Posted: 8/20/2006 3:11:01 PM EST
[#23]

Quoted:
I've seen very fast twist barrels cause lighter projectiles to come apart at higher velocities.

Very high velocities mixed very with fast twists can get projectiles pushing 30,000 RPM.  Even a small .223 projectile has a limit at how fast they'll spin and stay together.  Every projectile is different but there's a point they cannot be pushed past.


I have never had a 45, 52, or 53 grain bullet spin apart in my Ar15A2 1/7. I have heard it "can" happen but have never seen it personally. I used to whack the woodchucks with the 45gr varmint rounds as they were very effective. No problems, and quite accurate to boot out to 100 yards which was usually my longer shots. [sitting in the tree line of the woods]
Link Posted: 8/20/2006 4:12:30 PM EST
[#24]

Because most people buy cheap ammo to put through their cheap rifles.


Cheap rifles?  SKS type cheap?  I want the source of cheap AR15s!  You guys been holding out on me?
Link Posted: 8/20/2006 4:13:58 PM EST
[#25]
Ive had good luck with both 1/7 and 1/9. infact the 62gr I had shot best in the 1/9.
Link Posted: 8/20/2006 4:23:16 PM EST
[#26]
Cause 1/9 is better.
Link Posted: 8/20/2006 4:57:20 PM EST
[#27]
I've got 1:12, 1:9 and 1:7. I prefer 1:9.

I also used to have a 1:8, but I sold it.
Link Posted: 8/20/2006 5:05:35 PM EST
[#28]
The vast majority of military rifles are only used with issue M885 ammunition, so there's no question of the flexibility a somewhat slower twist gives being an issue.

On the other hand, if you want the "best of both worlds," and the ability to shoot light and heavy bullet rounds, then a compromise- 1/9 twist - is a good idea.

And geeze!  Please don't let us get off on that "chrome lined is what Jesus said we should all use" rant now?  Please?
Link Posted: 8/20/2006 5:32:48 PM EST
[#29]
me and a couple friends had an all day AR building festival yesterday.......all of them (except one retro 68 vintage M16 I finished) were all built using 1-7 inch twist barrels.

I like 1-7 and 1-8 inch twist barrels......have no need for anything else on an AR......
Link Posted: 8/20/2006 6:05:39 PM EST
[#30]
I prefer 1/9
Link Posted: 8/20/2006 6:13:18 PM EST
[#31]
Get both! just in case you run into some skinny zombies! or some thick ones for that matter then use 1/7 with 75grain TAP!!!
Link Posted: 8/20/2006 6:21:29 PM EST
[#32]

Quoted:
1/7 is a less compatible twist than 1/9, in that it does not work as well with as many different projectiles.

For the ultimate in heavy-weight tacti-cool rounds, you need a 1/7.  For most everything else 1/9 is a good twist.


Or even a 1 in 10 twist.
Shoots 55 to 62 grainers great and does even better with 40 to 52 grainers.
Link Posted: 8/20/2006 6:28:17 PM EST
[#33]
I think it's better to go too fast than too slow.  I don't think you can "over stabilize" a bullet to where it'll compromise accuracy or blow the bullet up, regardless of how light it is - I think that's done with muzzle velocity, too much or not enough, not too fast a twist.

1:8 is a good compromise overall.  Some 1:9s will shoot the longer bullets well.  I had a 1:9 Bushmaster barrel that'd shoot 75gr Hornadys and 77 SMKs pretty decently, they'd hold MOA out to 300 yards.  I had a 1:9 Savage .223 bolt gun that wouldn't shoot anything heavier than a 75 without patterning, not grouping.

My next upper will be a 1:6.5 or 1:7.
Link Posted: 8/20/2006 10:27:43 PM EST
[#34]

Quoted:
Because most people buy cheap ammo to put through their cheap rifles.


Douchebag answer.
Link Posted: 8/20/2006 11:21:20 PM EST
[#35]

Quoted:

Quoted:
Because most people buy cheap ammo to put through their cheap rifles.


Douchebag answer.


I put cheap ammo through my expensive rifle. How about that? Why, you ask? Because cheap ammo is....well, cheap, and I can shoot a lot of it at little cost. Plus, it's not going to damage my gun anyway.

I vote for 1/7, BTW. That said, 1/9 will serve most people very well.
Link Posted: 8/21/2006 12:44:51 AM EST
[#36]
Let the retards spout their blather about 1/9 and how great it is...


I'll be shooting my 77 and 75gr loads through my 1/7 thank you. Oh yea, I can shoot anything the 1/9 can anyway.

->



Link Posted: 8/21/2006 2:56:03 AM EST
[#37]
How is it that simple questions get asked around here and people then take the opportunbity to jump up on the soap box of overall opinion stating that what THEY have decided is the ultimate in Super Stealth Spec Ops answers and anything else is just stupid?  What happened to simply providing well grounded fact based information and letting other people decide.  This can certainly be followed up by opinion of what you think is best but without the added flair of anything else is st00pid.

Especially when people start spouting of stuff that just simply ain't right.

The 1:12 barrel is more or less limited to the 55gr XM193 round.  That being said the 20" Colt SP1 1:12 barrel is one hell of an accurate barrel, if 55gr. is all you want to shoot.  Most of the 1:12 barrels will shoot 62gr. SS109 rounds more or less decently in a pinch, but the groups do open up.  After about 100 meters, the accuracy will be more or less gone as the round will really begin to fall off due to lack of stability.  (That doesn't mean that there hasn't ever been a 1:12 that would shoot 62's to 300 yards, or that there hasn't been one that keyholed at 50 yards.  Just in general 55gr rounds will scream out of a 1:12 and anything heavier should only be run in an emergency.)

The 1:9 barrel (as has been said if you surf through the cesspool of opinion and banter in this thread) is a nice middle ground compromise.  It will run 55 and 62 grain rounds all day dropping them accurately out as far as the powder charge will allow.  There are some 1:9's that people say they can run heavier 75-77gr rounds through accurately. That is beyond the spec of the barrel though.

The 1:7 as covered many times over will run the longer heavier rounds that 1:12 and 1:9 won't.  Stainless and match barrels will be seen in 1:8.  The 1:8's will generally perform well up through 77gr. The 1:7 with run upwards of 80gr. rounds.

In theory the 1:7 will wear faster than 1:8 and 1:9 and 1:12.  Whether that will ever matter depends on the shooter, their habits, and usage.  Whether you need the faster twist is much the same.

Heavier .223 rounds whether commercial or reloader made are far more expensive than 55 and 62 grain rounds.  If you are really only going to ever care to shoot mainstream .223 defensive and mil-surp rounds, at least today, a 1:9 will do everything you ever need it to do.

If on the other hand you are going to spend the money and actually use/stockpile heavier rounds, then 1:7 or 1:8 is the way to go.

It's more or less that simple.

I've got 1:12, 1:9, 1:8, and 1:7 AR's


They all go bang.  They will all kill zombies.

But they all do that much more because of the ammo that is run in them than the barrel twist.

In other words Wolf .223 is a great plinking round and a horrible defensive round (the powder charge and resulting velocity are too low and the copper jacketing is way too thick to fragment)  XM193 level rounds will generally be effective inside 400.  Obviously you've got better terminal velocity the closer in you are with the snap in half or fragmentation level falling off about 400.

So I really think the question comes down to what are you going to shoot in your AR and what can you afford to stack deep?  It likely isn't 75 or 77 grain rounds for MOST people.

10k or 20k 55gr. mil-surp or Q3131 will run great from a 1:9 and since this is the price point the avergae Joe has a hope of stocking 10-20k rounds in, likely 1:9 is a great answer.

Link Posted: 8/21/2006 3:33:41 AM EST
[#38]
Link Posted: 8/21/2006 3:49:27 AM EST
[#39]
I've got a 1/12, a 1/9, and two 1/7s so I'm covered, thanks.
Link Posted: 8/21/2006 4:18:03 AM EST
[#40]
Link Posted: 8/21/2006 8:11:47 AM EST
[#41]

Quoted:

Quoted:
I've got a 1/12, a 1/9, and two 1/7s so I'm covered, thanks.


There ya go  It's hard to play golf with just one club.

Denny


Link Posted: 8/21/2006 8:20:52 AM EST
[#42]

Quoted:
How is it that simple questions get asked around here and people then take the opportunbity to jump up on the soap box of overall opinion stating that what THEY have decided is the ultimate in Super Stealth Spec Ops answers and anything else is just stupid?  What happened to simply providing well grounded fact based information and letting other people decide.  This can certainly be followed up by opinion of what you think is best but without the added flair of anything else is st00pid.

Especially when people start spouting of stuff that just simply ain't right.

The 1:12 barrel is more or less limited to the 55gr XM193 round.  That being said the 20" Colt SP1 1:12 barrel is one hell of an accurate barrel, if 55gr. is all you want to shoot.  Most of the 1:12 barrels will shoot 62gr. SS109 rounds more or less decently in a pinch, but the groups do open up.  After about 100 meters, the accuracy will be more or less gone as the round will really begin to fall off due to lack of stability.  (That doesn't mean that there hasn't ever been a 1:12 that would shoot 62's to 300 yards, or that there hasn't been one that keyholed at 50 yards.  Just in general 55gr rounds will scream out of a 1:12 and anything heavier should only be run in an emergency.)

The 1:9 barrel (as has been said if you surf through the cesspool of opinion and banter in this thread) is a nice middle ground compromise.  It will run 55 and 62 grain rounds all day dropping them accurately out as far as the powder charge will allow.  There are some 1:9's that people say they can run heavier 75-77gr rounds through accurately. That is beyond the spec of the barrel though.

The 1:7 as covered many times over will run the longer heavier rounds that 1:12 and 1:9 won't.  Stainless and match barrels will be seen in 1:8.  The 1:8's will generally perform well up through 77gr. The 1:7 with run upwards of 80gr. rounds.

In theory the 1:7 will wear faster than 1:8 and 1:9 and 1:12.  Whether that will ever matter depends on the shooter, their habits, and usage.  Whether you need the faster twist is much the same.

Heavier .223 rounds whether commercial or reloader made are far more expensive than 55 and 62 grain rounds.  If you are really only going to ever care to shoot mainstream .223 defensive and mil-surp rounds, at least today, a 1:9 will do everything you ever need it to do.

If on the other hand you are going to spend the money and actually use/stockpile heavier rounds, then 1:7 or 1:8 is the way to go.

It's more or less that simple.

I've got 1:12, 1:9, 1:8, and 1:7 AR's


They all go bang.  They will all kill zombies.

But they all do that much more because of the ammo that is run in them than the barrel twist.

In other words Wolf .223 is a great plinking round and a horrible defensive round (the powder charge and resulting velocity are too low and the copper jacketing is way too thick to fragment)  XM193 level rounds will generally be effective inside 400.  Obviously you've got better terminal velocity the closer in you are with the snap in half or fragmentation level falling off about 400.

So I really think the question comes down to what are you going to shoot in your AR and what can you afford to stack deep?  It likely isn't 75 or 77 grain rounds for MOST people.

10k or 20k 55gr. mil-surp or Q3131 will run great from a 1:9 and since this is the price point the avergae Joe has a hope of stocking 10-20k rounds in, likely 1:9 is a great answer.



How 'bout everyone reading this does a copy/paste of this post by 2FALable and everytime someone asks the question... slap this in as the first reply (giving credit to 2FALable)... then mods should lock the thread.
Link Posted: 8/21/2006 8:46:12 AM EST
[#43]
To 2FALable:

Thank you very much!  


They all go bang. They will all kill zombies.

Link Posted: 8/21/2006 9:10:54 AM EST
[#44]
Sweet.  I had always just been pointed to the Ammo Oracle.  No one ever took the time to spell it out for me either.  
Link Posted: 8/21/2006 9:32:08 AM EST
[#45]

Quoted:

Quoted:

Quoted:
What does the .gov have their rifles in? 1-9 or 1-7?



1/7


What's the downside to 1/7?




Only rarity and cost.
Link Posted: 8/21/2006 9:35:30 AM EST
[#46]

Quoted:
I've seen very fast twist barrels cause lighter projectiles to come apart at higher velocities.
.


I would love to see that.  i have tried and tried, shooting .223 bullets as light as 35Gn from my 20" 1:7 and have not been able to make a bullet self destruct from the RPMs yet.  

Link Posted: 8/21/2006 9:42:00 AM EST
[#47]
I have one 20" 1:12 SP1.  it shoots great with BH 52Gn, M193 & pretty good with various 60Gn Soft points too.  It will not work with the 64Gn Powerpoint though.

My 24" Stainless 1:9 shoots great with powerpoints and Horn 75Gn OTM.

My several 14.5" 1:9 Brls work great with M193 but do not stabilise Horn 75Gn or BH 77Gn OTM.

My 1:7 rifles will stabilize anything from 45Gn JHP to 77Gn OTM.l  
Link Posted: 8/21/2006 9:44:51 AM EST
[#48]

Quoted:
Dang, seen all kinds of cheap talk on this subject.


Yeah.. you included...  see below.


And I dont want to even talk about the old 1:12 twist which is only good for 50 grain and down.


WRONG!  The 1/12 twist is optimal for accuracy with the 55 grain bullet.  The military chart has been posted here before.



In short, you need to spin up them heavy bullets or have them tumbling down range all over the place.


Wrong again.  It's the length of the bullet not the weight that require faster twist.  For example the 50 grain frangible will sometimes not stabilize out of a 1/9 barrel.  It's a VERY LIGHT, but VERY LONG projectile.

Link Posted: 8/21/2006 10:51:04 AM EST
[#49]

Quoted:
Because most people buy cheap ammo to put through their cheap rifles.
+1
Link Posted: 8/21/2006 11:57:12 AM EST
[#50]
Same reason all barrels aren't 16" long.

different strokes.
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