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Posted: 9/14/2011 10:33:18 AM EST
Hey folks,
got a AR15 in .223 Rem. with this barrel.

How heavy can I go with it?

1/9" is a long twist.
I want to make loads for up to 300 yards.

How heavy have the bullets to be therefore?
Has anybody load datas with "heavier" bullets for this barrel config?

Need some help.
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Link Posted: 9/14/2011 10:48:47 AM EST
Lots of loads under the Armory/Reloading section here, plus many other web sites. It's been my experience the 69 grainers is about as heavey as a 1/9 likes. There are exception of course. The lenght and profile of your barrel will give you a bit of a volicity advantage and maybe a little stiffness will help with shot to shot consistancy, but the rate of twist is what governs it bullet weight preferences. Try some 62 and 69 grainers at mid-level speed and see how your gun likes them. Varget and R-15 give me good results. My best 69 grain load is right out of the Sierra manuel, 25.3 grains of Varget under their HPBT MatchKing. However 62 and 55 grain bullets shoot a little smaller group in my gun.
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Link Posted: 9/14/2011 11:16:56 AM EST
For what it's worth, I bought factory 77gr .223 and shot it in my RRA entry tactical (16" bbl and 1:9 twist). I know the bullets stabilized, because there were clean holes in the target and not keyholes. They did not group all that well for me at 200yds, but that may have been more my shooting than the actual performance. The real question is what do you need? If you are shooting 3-gun matches, 55 or 62 gr ammo will more than satisfy without breaking the bank. If you are shooting bullseye/high power style competitions then the 77gr will give you more consistency in windy conditions. If you get a book on ballistics and do some math, you will see that the wind has to really be blowing to see a large difference in bullet perfomance (that is between 55, 62, 69, and 77 gr)
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Link Posted: 9/14/2011 1:44:44 PM EST
75 Hornady match bullets have stabilized in every 1-9 twist I have ever seen, and lots of people report the same.
If the man can't do it, the rifle can't either...
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Link Posted: 9/14/2011 4:31:19 PM EST
You will really just have to try some and see for yourself. The barrels vary. I have not had a problem with stability, just not terribly accurate with heavier than 69 gr bullets. A friend shoot the heavies from his 1/9 all day long with excellent results. Also has good results with 75gr AMax which are really long.
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Link Posted: 9/14/2011 6:36:13 PM EST
in my expierence, as many have already said, yes, you can go heavy on the bullet, but lighten the charge.

only one way to find out.....
Im getting tight patterns with 69gr sierra and 25.2 grs worth of varget...your mileage may vary
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Link Posted: 9/14/2011 6:39:13 PM EST
Originally Posted By panzer:
75 Hornady match bullets have stabilized in every 1-9 twist I have ever seen, and lots of people report the same.


They do not in one of my ARs
fine at 50 off paper at 100
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Link Posted: 9/14/2011 7:37:21 PM EST
Originally Posted By jayjay1:
Hey folks,
got a AR15 in .223 Rem. with this barrel.

How heavy can I go with it?

1/9" is a long twist.
I want to make loads for up to 300 yards.

How heavy have the bullets to be therefore?
Has anybody load datas with "heavier" bullets for this barrel config?

Need some help.


Maybe you should try and run a few samples through it before you stock up on components. For example, you may find that 55gr loads do fine at 300, then work your way up.
Odds are you will be happy with the weight range up to about 73 boat tails according the the chart on 6BR.com

http://www.6mmbr.com/223Rem.html

Try some Black Hills 69 SMK loads first and see how they do for example. If those don't work well, you could drop to 62 or 60 grain loads and you should be in the x-ring.



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Link Posted: 9/14/2011 7:38:13 PM EST
The 69 grain bullet was made to get to 600 yards. At 300 yards, pretty much anything will get there. If you are looking for pure accuracy, try a 52 grain bullet. They are cheaper than the 68/69 grainers, too.

A standard speed .22 will go out to ~275 yards accurately. A 223 will certainly do it with anything. It ain't that far!
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Link Posted: 9/15/2011 2:06:20 AM EST
Hey folks,

thanx a lot, great comments!
In the register that I have here from an elder reloader book, 69grs. is the heaviest bullet you should go for in a 1/9"-twist barrel.
I was unsure, how much bullet weight I would need to shoot precise and certain (wind!) on 300yds..

Well, I tried bullets with 52, 60 and 69 grs. from Sierra, Nosler and Hornady.
Still having enough from them.

I took them for shooting on 100 yds., the loads where just on the upper line - high velocity - to check the function of the weapon too.
The 52 had all very well groups, the 60s had one and the 69ers had no tight group (but holding the black on the ISSF sight disk).

On my home range I just can shoot 100 yds., but three or four times in the year we´re going to shoot up to 300yds. on a range a bit further away.

After your response here I will reduce the load and see what happens.

Faithful to the reloaders first rule here on the old continent:
"Practice is the death of all theory."


Gentlemen, I want to thank you for helping me out in this.

King regards,
J.



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Link Posted: 9/15/2011 1:41:57 PM EST
I've shot 69 gr. SMK out to 600 yards with 22.5 gr. of H335, with good results through my 20" 1:9 barrel.

Did that because all the books said 69 grain bullets were the heaviest that could be accurately used in a 1:9 barrel. I now believe that's more of a guideline than a rule.

Next time I shoot at 600 yards, I will try 72 gr. and/or 75 gr. bullets and see what happens.

Personally, I think no two barrels are alike. You have to do a test with your own rifle and record the results.
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Link Posted: 9/15/2011 7:45:47 PM EST
Originally Posted By BikerNut:
I've shot 69 gr. SMK out to 600 yards with 22.5 gr. of H335, with good results through my 20" 1:9 barrel.

Did that because all the books said 69 grain bullets were the heaviest that could be accurately used in a 1:9 barrel. I now believe that's more of a guideline than a rule.

Next time I shoot at 600 yards, I will try 72 gr. and/or 75 gr. bullets and see what happens.

Personally, I think no two barrels are alike. You have to do a test with your own rifle and record the results.


You are correct. We know when we push things too far and the instability becomes obvious because we are watching in the lab. But it is a gray zone, not a hard line.
Because some bbls/guns react a little differently, some bullets fly well at a twist rate that isn't stable out of a different rig with the same twist.

In the end, it is best to stay away from the edges of stability in order to keep some margin. The basic relationships are still true, it is just that the lines are soft and not black and white.
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Link Posted: 9/15/2011 7:51:01 PM EST
Selling agent for Algores carbon credit scam.

Shooting and Reloading, one hobby feeds the other.


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Link Posted: 9/16/2011 12:17:39 AM EST
"Practice is the death of all theory!"

I learned this from my father and will teach it to my son.
It´s a lot of truth in that, so my experience.
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Link Posted: 9/16/2011 12:24:57 AM EST
Originally Posted By BikerNut:
I've shot 69 gr. SMK out to 600 yards with 22.5 gr. of H335, with good results through my 20" 1:9 barrel.


Well, this seems to me as a little load for this bullet.

But this shows, that a heavier bullet might be better stabilized in a "long" - twisted barrel with less powder.
I will proof this with my rifle, having the 69 gr. SMK right here.

But I also want to give you something back.
My best load with this barrel till now is with the Nosler 60 gr. Ballistic Tip Varmint Spitzer with 20,5 gr. VV N130 behind it.


Greetz,
J.

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Link Posted: 9/16/2011 5:35:45 AM EST
Originally Posted By Elwood_Blues:
The 69 grain bullet was made to get to 600 yards. At 300 yards, pretty much anything will get there. If you are looking for pure accuracy, try a 52 grain bullet. They are cheaper than the 68/69 grainers, too.

A standard speed .22 will go out to ~275 yards accurately. A 223 will certainly do it with anything. It ain't that far!


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Link Posted: 9/17/2011 2:28:47 PM EST
[Last Edit: 9/17/2011 2:55:36 PM EST by KRONIIK]
Originally Posted By MTNmyMag:
Originally Posted By panzer:
75 Hornady match bullets have stabilized in every 1-9 twist I have ever seen, and lots of people report the same.


They do not in one of my ARs
fine at 50 off paper at 100


Interesting!
I've had extraordinary results with the 75 Hornady BTHP bullet at 600 yards; 3-4-inch groups in my factory Bushmaster 1-9 , 20-inch.

The 75 A-Max at similar velocities ran off the rails completely, though.
Dismal accuracy; someting more like 4 inches at 100 yards!
The bullets are the same weight, but the Hornady BTHP is on the right side of that ambiguous line for that barrel while the higher BC, more aerodynamic, but less -easily stabilized Hornady A-Max is on the other side of it, I guess...

edited for spelling.
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Link Posted: 9/17/2011 2:48:20 PM EST
I have had good luck with Sierra 65 gr boat tails............not the heaviest bullet out there, but they work well for me at 300yds.
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Link Posted: 9/17/2011 4:50:45 PM EST
Originally Posted By MTNmyMag:
Originally Posted By panzer:
75 Hornady match bullets have stabilized in every 1-9 twist I have ever seen, and lots of people report the same.


They do not in one of my ARs
fine at 50 off paper at 100


Very good info, You might want to try the Berger 73 LTB. I have a 1/9 M700 5R that will stabilize a 77.. hmm. Maybe I have a "fast" 1-9, and you have a "slow" 1-9.
Its too bad your rifle doesn't like the 75, its a nice bullet.

On anothe note, its really about length not weight, although the heavier ones are usually longer. The 75 Amax is longer, but same weight as the regular 75, so it won't stabilize in a 1-9 that a regular one will, due to its increased length. make sense?

If the man can't do it, the rifle can't either...
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Link Posted: 9/17/2011 4:53:37 PM EST


This is why I'll NEVER EVER own an AR with a 1:9 barrel. It's 1:8 or 1:7 or nothing!

You're simply going to have to test your own rifle against the load. I've seen 20" A2 barrels shoot 75's to 600 with no effort but wouldn't shoot an AMAX and vice versa. 16" M4gery 1:9's are even more persnickety, some will shoot 75's no problem while others won't stabilize a 69.

You don't have this trouble with a 1:7 even in a carbine.
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Link Posted: 9/17/2011 5:42:07 PM EST
[Last Edit: 9/17/2011 5:45:09 PM EST by Anaxes]
The most common load for 300yds here would be a 69gn SMK HPBT with either Varget or Viht N140. I use Lapua Scenar HPBT instead, but the same powder. I haven't been able to test much, but my initial results seem to suggest 77gn Lapua Scenar work well from a Steyr AUG (20" inch - 1 in 9 twist barrel) at 300yds. We also tend to use Varget or N140 with 77gn bullets. I was using Varget.

Someone mentioned Berger 73gn earlier, which are reputedly very good with 1 in 9 twist barrels. I have some, but have been hesitant to experiment much with them due to availability problems. They are certainly a good quality bullet.
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Link Posted: 9/17/2011 7:42:09 PM EST
Originally Posted By panzer:
Originally Posted By MTNmyMag:
Originally Posted By panzer:
75 Hornady match bullets have stabilized in every 1-9 twist I have ever seen, and lots of people report the same.


They do not in one of my ARs
fine at 50 off paper at 100


Very good info, You might want to try the Berger 73 LTB. I have a 1/9 M700 5R that will stabilize a 77.. hmm. Maybe I have a "fast" 1-9, and you have a "slow" 1-9.
Its too bad your rifle doesn't like the 75, its a nice bullet.

On anothe note, its really about length not weight, although the heavier ones are usually longer. The 75 Amax is longer, but same weight as the regular 75, so it won't stabilize in a 1-9 that a regular one will, due to its increased length. make sense?



I have two 1-9's and one 1-8 The 1-9 that will stabilize the 75s is a 20" Bushmaster the Stag M4 barrel will not stabilize, but Its my HD carbine and it does fine at 50 yards so I still load it.
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Link Posted: 9/18/2011 2:38:00 AM EST
[Last Edit: 9/18/2011 2:55:27 AM EST by DakotaFAL]
There are a few issues people are hinting at but stop slightly short of mentioning.

1) It's the length that matters (this one was mentioned by one poster) not the weight. All other things being equal it does not matter, but plastic ballistic tips, hollow cores, steel penetrators, comparatively light weight tracer compounds, long match type point designs and designs using a longer than normal ogive can all add extra length to a round of a given weight.

2) when the powers that be were adopting a barrel twist for the M16A2 they recognized that the 1-9 twist was ideal for the SS109/M855 round (and was generally ideal for a lead core jacketed bullet in the 62 grain weight range.). However the M856 tracer round was substantially longer and would not stabilize out to the required range, so a faster twist was adopted to stabilize that round - even though it is seldom used in M16s or M4s.

3) velocity matters. What stabilizes the bullet is the rotational velocity / rpms. That is a product of both barrel twist and muzzle velocity, so a long bullet may stabilize in a slow twist barrel at a near maximum muzzle velocity and not stabize at a slower velocity.

4) applying #3, barrel length matters. You will note lots of college about x bullet staining in a 20" but not a 16" barrel. It's not a product of the length of the barrel in terms of more rifling, but rather a product of shorter barrels imparting less initial velocity and thus fewer revolutions per minute to the bullet.

To make this concept easier to grasp you can demonstrate it with small numbers and a 1 in 1 ft twist rate. If I fire a bullet at 1 fps through a 1-12 barrel, it will leave the barrel rotating 1 revolution per second (60 rpm). If I increase the velocity to 2 fps, it will exit at 2 revolutions per second (120 rpm) and continuing this increase, 3 fps equals 180 rpm, and 4 fps equals 240 rpm. I can get the same 240 rpm however using a 1-24 twist barrel and a velocity of 8 fps.

The same thing happens with 2000-3000 fps muzzle velocities, the numbers just get much larger. If I launch a 75 gr bullet at 2600 fps out of a 20" 1-9 barrel it will be spinning at about 208,000 rpm. If I shoot the same round out of a 16" 1-9 twist barrel and only get an MV of 2200 fps, then the rpm falls to 176,000 rpm - a 16% decrease in spin. The former round will be well stabilized while the latter is extremely marginal with a long 75 gr bullet and if it stabilizes, it may not stay that way beyond 100-200m.

5) range matters. bullets don't lose much spin down range, but they do lose some. And more importantly if a marginally stable bullet is yawing slightly around it's axis, the aerodynamic forces on the nose will cause it to precess - moving the bullet in a direction 90 degrees off the direction where it was pushed, and that is what quickly degrades accuracy.

6) quality matters. If a bullet is perfectly made, the center of form and the center of mass share the same point in the center of the bullet. However if those two points differ, the bullet will exit the barrel rotating around the center of form and then must transition to rotating around the center of mass. That transition before the bullet settles down causes the bullet to yaw slightly, and if it is only marginally stable, it will not dampen the yaw moments, they will amplify and the bullet will destabilize.

(The same issues effect low quality, lightweight bullets that are fired in 1-7 barrels with excess spin resulting. While accuracy with good quality bullets remains good, poor quality bullets experience greater yaw and precession after exiting the barrel and demonstrate accuracy that is worse than would have been the case in a 1-9 or 1-12 barrel. However in this case the lower velocity in carbine barrels reduces the spin and improve accuracy. Differences in barrel length and bullet quality account for much of the disagreement in the 55 gr / 1-7 twist argument.)

––––

Consequently:
- longer bullets require more twist than shorter bullets regardless of weight,
- slowing a bullet down will not improve the stability situation if it is already only marginally stable,
- shorter barrels present greater stability challenges due to lower velocities,
- higher quality bullets are easier to stabilize than lower quality bullets
- a bullet that makes shooter "A" happy by stabilizing out to 100-300m may not please shooter "B" who is shooting at 600m
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Link Posted: 9/18/2011 7:25:20 AM EST
Originally Posted By DakotaFAL:
There are a few issues people are hinting at but stop slightly short of mentioning.

1) It's the length that matters (this one was mentioned by one poster) not the weight. All other things being equal it does not matter, but plastic ballistic tips, hollow cores, steel penetrators, comparatively light weight tracer compounds, long match type point designs and designs using a longer than normal ogive can all add extra length to a round of a given weight.

2) when the powers that be were adopting a barrel twist for the M16A2 they recognized that the 1-9 twist was ideal for the SS109/M855 round (and was generally ideal for a lead core jacketed bullet in the 62 grain weight range.). However the M856 tracer round was substantially longer and would not stabilize out to the required range, so a faster twist was adopted to stabilize that round - even though it is seldom used in M16s or M4s.

3) velocity matters. What stabilizes the bullet is the rotational velocity / rpms. That is a product of both barrel twist and muzzle velocity, so a long bullet may stabilize in a slow twist barrel at a near maximum muzzle velocity and not stabize at a slower velocity.

4) applying #3, barrel length matters. You will note lots of college about x bullet staining in a 20" but not a 16" barrel. It's not a product of the length of the barrel in terms of more rifling, but rather a product of shorter barrels imparting less initial velocity and thus fewer revolutions per minute to the bullet.

To make this concept easier to grasp you can demonstrate it with small numbers and a 1 in 1 ft twist rate. If I fire a bullet at 1 fps through a 1-12 barrel, it will leave the barrel rotating 1 revolution per second (60 rpm). If I increase the velocity to 2 fps, it will exit at 2 revolutions per second (120 rpm) and continuing this increase, 3 fps equals 180 rpm, and 4 fps equals 240 rpm. I can get the same 240 rpm however using a 1-24 twist barrel and a velocity of 8 fps.

The same thing happens with 2000-3000 fps muzzle velocities, the numbers just get much larger. If I launch a 75 gr bullet at 2600 fps out of a 20" 1-9 barrel it will be spinning at about 208,000 rpm. If I shoot the same round out of a 16" 1-9 twist barrel and only get an MV of 2200 fps, then the rpm falls to 176,000 rpm - a 16% decrease in spin. The former round will be well stabilized while the latter is extremely marginal with a long 75 gr bullet and if it stabilizes, it may not stay that way beyond 100-200m.

5) range matters. bullets don't lose much spin down range, but they do lose some. And more importantly if a marginally stable bullet is yawing slightly around it's axis, the aerodynamic forces on the nose will cause it to precess - moving the bullet in a direction 90 degrees off the direction where it was pushed, and that is what quickly degrades accuracy.

6) quality matters. If a bullet is perfectly made, the center of form and the center of mass share the same point in the center of the bullet. However if those two points differ, the bullet will exit the barrel rotating around the center of form and then must transition to rotating around the center of mass. That transition before the bullet settles down causes the bullet to yaw slightly, and if it is only marginally stable, it will not dampen the yaw moments, they will amplify and the bullet will destabilize.

(The same issues effect low quality, lightweight bullets that are fired in 1-7 barrels with excess spin resulting. While accuracy with good quality bullets remains good, poor quality bullets experience greater yaw and precession after exiting the barrel and demonstrate accuracy that is worse than would have been the case in a 1-9 or 1-12 barrel. However in this case the lower velocity in carbine barrels reduces the spin and improve accuracy. Differences in barrel length and bullet quality account for much of the disagreement in the 55 gr / 1-7 twist argument.)

––––

Consequently:
- longer bullets require more twist than shorter bullets regardless of weight,
- slowing a bullet down will not improve the stability situation if it is already only marginally stable,
- shorter barrels present greater stability challenges due to lower velocities,
- higher quality bullets are easier to stabilize than lower quality bullets
- a bullet that makes shooter "A" happy by stabilizing out to 100-300m may not please shooter "B" who is shooting at 600m


Excellent!
My experiences fully support your observations, without exception.

Lots of factors all come into play together, and it can be hard to figure out which one is a culprit when there may in fact be several of them...
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Link Posted: 9/18/2011 9:18:21 AM EST
This is why I'll NEVER EVER own an AR with a 1:9 barrel. It's 1:8 or 1:7 or nothing!


There is a camp of individuals that think the fast twist rates actually HURT the performance of 223, and that over stabilization actually has reduced the capability of the round. Go back, it was 1 in 14 and then 1 in 12.

In my opinion, 1 in 9 at 20 " is an excellent choice. My A1 has a 1 in 9 and shoots 69 SMKs most accurately. Unless you're made of money, there's no escaping shooting a lot of 55 or 62 gr ammo, in which case the 1/9 is a great choice. There are numerous posts of light bullets being spun apart by 1 in 7s too...

Are you competition shooting 600 yards? Sure get the 1 in 7... are you shooting/plinking out to 300 yards as the OP said.. 1 in 9 at 20" is not a problem. I have 2 1 in 7s to compare with and frankly, up to the 69s, you can't tell much of a difference... they all shoot well.
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Link Posted: 9/18/2011 9:55:54 AM EST



Sell your barrel on equipment exchange and buy a 1:7 or 1:8

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Link Posted: 9/18/2011 10:05:00 AM EST
2) when the powers that be were adopting a barrel twist for the M16A2 they recognized that the 1-9 twist was ideal for the SS109/M855 round (and was generally ideal for a lead core jacketed bullet in the 62 grain weight range.). However the M856 tracer round was substantially longer and would not stabilize out to the required range, so a faster twist was adopted to stabilize that round - even though it is seldom used in M16s or M4s.


Get yourself a box of M855 and try it. The M855 has a 62gn steel core bullet that flys crazy accurate out of a 1/9. I did it and now its all I will load for anything with a 1/9 twist. I recently found some of the "newer" 62gn federal fusion bullets on the EE that have been working better than anything else that I have previously loaded.
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Link Posted: 9/18/2011 12:03:45 PM EST
[Last Edit: 9/18/2011 12:04:40 PM EST by DakotaFAL]
Originally Posted By telemarker:
2) when the powers that be were adopting a barrel twist for the M16A2 they recognized that the 1-9 twist was ideal for the SS109/M855 round (and was generally ideal for a lead core jacketed bullet in the 62 grain weight range.). However the M856 tracer round was substantially longer and would not stabilize out to the required range, so a faster twist was adopted to stabilize that round - even though it is seldom used in M16s or M4s.


Get yourself a box of M855 and try it. The M855 has a 62gn steel core bullet that flys crazy accurate out of a 1/9. I did it and now its all I will load for anything with a 1/9 twist. I recently found some of the "newer" 62gr federal fusion bullets on the EE that have been working better than anything else that I have previously loaded.
That's what the US military found as well. 1-9 twist is ideal for M855 especially in a 20" barrel. 1-7 was adopted in the M16A2 only to allow M856 to be fired and remain stable out to 800m just like the M249 and despite the hordes or mil-spec fanatics who feel 1-7 is ideal regardless of barrel length since it is "mil-spec". In truth its more complex than that as it brings with it some significant compromises in a 20" barrel.

In a shorter 14.5" or 16" barrels the adverse effects on lighter bullets are less pronounced due to lower velocity, and the faster twist does allow them to stabilize longer bullets that would not perform as well in a 1-9 twist barrel of similar length.
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Link Posted: 9/18/2011 12:23:52 PM EST
the M16A2 was developed back in the early 1980's

Yes, 1:7 was chosen because of the longer TRACER rounds.

It was years later that SIERRA, NOSLER, etc., developed heavy 77gr long range match bullets.

these bullets, along with fast twist barrels made the AR15 a serious contender in SERVICE RIFLE competition

Prior to this, the M-14 types rifles were the dominant rifle at Camp Perry


Later, it was discovered that in addition to better LONG RANGE ACCURACY, the 77gr have SUPERIOR wounding characteristics


http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm#.223






Why anyone would limit themselves from being able to use 77gr is something I'll never understand.

1:7 is a better choice than 1:9


Also, the best 100 yrd groups I've ever shot have been with 55gr VMAX handloads and a 1:7 twist barrel, 1:7 has no trouble with 55gr either.
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Link Posted: 9/18/2011 2:50:23 PM EST
[Last Edit: 9/18/2011 3:15:28 PM EST by DakotaFAL]
1) M856=TRACER

2) The terminal ballistics with the M855 were poor compared to M193 in a 20" barrel mostly due to the lower velocity but the longer bullet was somewhat more likely to fragment so it was not a total retrograde step and at the time it was considered more "humane".

However, fast forward to the M4 with a 14.5" barrel and even lower velocities, and suddenly the range at which it would fragment OR tumble was no more than about 45-50m - adequate for other than CQB. Thus longer, heavier 77 gr bullets were used in the MK 262 round to increase lethality at longer ranges in M4 carbines as well as in SPRs.

3) the question of why would anyone not choose 1-7 twist is that not everyone is striving for maximum accuracy with a 77 gr match bullet at 600m. Many shooters will spend the majority if their time shooting at ranges of 25m-300m where getting reasonable accuracy out of inexpensive bulk 55 gr FMJs and SPs or pulled down surplus M193 or M855 projectiles. Given the inconsitency in a bulk comercial bullet or a pulled down bullet, excessive twist does not make sense.

4) the bigger question is why would anyone limit themselves to just one AR?

Personally, I prefer 1-9 twist in my 16" ARs and standard weight 20" ARs, I also prefer 1-9 in my bull barrel varmint AR as it is more accurate with 50-55 grain bullets (and when 500 rounds a day is not uncommon, cost is a factor and 77 gr match bullets would be cost prohibitive) and finally, I prefer 1-8 twist in my match AR.

But I gotta say I still miss the M1A days.

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Link Posted: 9/18/2011 3:21:37 PM EST
[Last Edit: 9/18/2011 3:25:43 PM EST by jaholder1971]
Originally Posted By Cycline3:
This is why I'll NEVER EVER own an AR with a 1:9 barrel. It's 1:8 or 1:7 or nothing!


There is a camp of individuals that think the fast twist rates actually HURT the performance of 223, and that over stabilization actually has reduced the capability of the round. Go back, it was 1 in 14 and then 1 in 12.

In my opinion, 1 in 9 at 20 " is an excellent choice. My A1 has a 1 in 9 and shoots 69 SMKs most accurately. Unless you're made of money, there's no escaping shooting a lot of 55 or 62 gr ammo, in which case the 1/9 is a great choice. There are numerous posts of light bullets being spun apart by 1 in 7s too...

Are you competition shooting 600 yards? Sure get the 1 in 7... are you shooting/plinking out to 300 yards as the OP said.. 1 in 9 at 20" is not a problem. I have 2 1 in 7s to compare with and frankly, up to the 69s, you can't tell much of a difference... they all shoot well.


1:7 isn't optimal for lighter bullets, I'll agree. However I've shot bullets as light as 45 grains in both of my 1:7 barrels with zero issues. Accuracy was within .25-.5 MOA on average compared with my heavier loads. You won't do that with 75/77's in a 1:12. I'd rather have a rifle with a twist rate that will shoot everything with acceptable accuracy over one that won't.

Yes, I've blown up light bullets driving them hard through my AR, I've done the same thing in my Steven 200 sporting a 1:9, too. The ultra thin jacketed 40 grain blitz type bullets were designed for the .22 Hornet and won't hold together at higher velocities. A light bullet with a thicker jacket will do just fine.
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Link Posted: 9/18/2011 10:23:18 PM EST
Well, after reading all of this (and understanding most of it ) I´m asking myself if it wouldn´t be helpful to list load datas addicted to the barrel twist?

Is there a list of datas in relationship to this?

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Link Posted: 9/19/2011 5:35:16 PM EST
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Link Posted: 9/20/2011 12:08:51 AM EST
Originally Posted By dryflash3:
A general guideline is 69 gr bullet is the heaviest bullet to use with a 1 in 9 twist.

Your going to have to do some shooting to determine what you barrel likes or not.

Good luck


Of course I know that, but thanks either for that.

I just was asking how heavy I must go, to get precise shots above 300yrds., "independent" from wind an so.

Right now the best results overall brings the 60gr. Nosler Ballistic Varmint Spitzer.
But unfortunately this is quiet an expensive bullet over here.
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Link Posted: 9/20/2011 8:01:35 AM EST
[Last Edit: 9/20/2011 8:02:47 AM EST by DakotaFAL]
Originally Posted By dryflash3:
It goes by bullet weight not load data.

Certain twists work best with certain bullet weights.

Some barrels will shoot heavy bullets is slow twists.

A general guideline is 69 gr bullet is the heaviest bullet to use with a 1 in 9 twist.

Of course there are exceptions, like in the above posts.

Your going to have to do some shooting to determine what you barrel likes or not.

My 1 in 9 twist heavy barrel, 16 inch AR loves the 69 gr Sierra MK, and throws patters with a 75 gr Hornady.

Good luck
It's a general guideline in the sense of applying to the AR - regardless of barrel length.

As you know, with the lower velocity that comes with a shorter barrel, the 77 gr bullet does not stabilize.

That is however not the case with a 20" or 24" barrel.



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Link Posted: 9/20/2011 8:07:38 AM EST
Originally Posted By jaholder1971:
1:7 isn't optimal for lighter bullets, I'll agree. However I've shot bullets as light as 45 grains in both of my 1:7 barrels with zero issues. Accuracy was within .25-.5 MOA on average compared with my heavier loads. You won't do that with 75/77's in a 1:12. I'd rather have a rifle with a twist rate that will shoot everything with acceptable accuracy over one that won't.

Yes, I've blown up light bullets driving them hard through my AR, I've done the same thing in my Steven 200 sporting a 1:9, too. The ultra thin jacketed 40 grain blitz type bullets were designed for the .22 Hornet and won't hold together at higher velocities. A light bullet with a thicker jacket will do just fine.


I'm interested in what bullets you used and the barrel lengths involved.

As noted above, if the bullet is precisely made, there is less of an issue transitioning from rotation around the center of form to the center of mass, thus less yaw, less precession and less threat to overall stability.

However with a cheap bulk bullet or pulled surplus bullet, getting accuracy in a 1-7 barrel can be a much greater challenge while the same bullet may be acceptably accurate in a 1-9 twist barrel.

Barrel length also matters and 1-7 is less problematic with light bullets in 10", 11", 14.5" and 16" barrels than it is in 18", 20" or 24" barrels.



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Link Posted: 9/20/2011 9:19:09 AM EST
Remember Braydon Nichols and his Dad, Chinook Pilot CWO Bryan Nichols, KIA in Afghanistan 6 August 2011
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