I am getting a 223 with a 1-12 twist. How heavy a bullet will this twist stabilize within the capabilities of this ctg?

Thanks,

Andy

Remember bullet length is what counts, not weight. A 1-12 twist in .223 Rem. should comfortably stabilize bullets up to about 0.75" long.

To give a couple of examples, the Hornady A-Max 52 gr. bullet is 0.80" long. It will likely stabilize but it will be close. Under some conditions, very cold temperatures for example, it might not.

The Hornady 60 gr. spire point is 0.700" long and should stabilize easily in a 1-12 twist.

quote:

Remember bullet length is what counts

Darn right.

For whatever reason, Sierra 69 gn Matchkings generally shoot very well out of 1:12 barrels.

I tried the 69 SMKs (which measures 0.900" long) in my Rem 700 with 1-12 twist, they were going through the paper sideways at 25 yards. At 100 yards the first shot missed paper and cut off the wire leg of my target stand.

This was at an elevation of about 1800 ft. and 60F. At 5000 or 6000 ft. on a hot day it should be borderline stable.

quote:

Originally posted by Dave Anderson:
I tried the 69 SMKs (which measures 0.900" long) in my Rem 700 with 1-12 twist, they were going through the paper sideways at 25 yards. At 100 yards the first shot missed paper and cut off the wire leg of my target stand.

This was at an elevation of about 1800 ft. and 60F. At 5000 or 6000 ft. on a hot day it should be borderline stable.

Dave, not doubting you but that seems unusual. Some the 14 twist 22-250's will stabilize the 63 grain Sierra semi point...not all of them. Funny that 12 twist of yours won't stabilize a 6 grain heavier bullet even if it is a tad longer then that 63 grain. Funny the poster ahead of you said most 12 twist rifles shoot them fine. Have you ever tried those 63 semi points?

quote:

Originally posted by Dave Anderson:
Remember bullet length is what counts, not weight. A 1-12 twist in .223 Rem. should comfortably stabilize bullets up to about 0.75" long.

To give a couple of examples, the Hornady A-Max 52 gr. bullet is 0.80" long. It will likely stabilize but it will be close. Under some conditions, very cold temperatures for example, it might not.

The Hornady 60 gr. spire point is 0.700" long and should stabilize easily in a 1-12 twist.

I have shot close to a thousand 52 gr. A-Max bullets out of my 14 twist 22-250. They have been extremely accurate. Likewise the 52 gr low drag JLK bullets. I just received another thousand of these.
Both of these bullets are shooting .4 MOA out of my Cooper, and about 3000 rounds ago, they were shooting in the .3's.
Hornady does suggest a 12 twist for the 53 gr V-Max.

Rate of twist is an important factor, but don't forget muzzle velocity, temperature, and altitude. For example the MV of the 69 SMK in my 1-12 .223 is about 2,850 fps, and as mentioned I was shooting at 1,800 feet elevation and around 60F.

From a .22-250 or .220 Swift it will leave the muzzle at higher velocity and therefore be spinning faster, even if both barrels are 1-12 twist. Bullets are also more stable at higher elevations and at higher temperatures.

Stability isn't a yes/no thing. Bullets go through a range from unstable, to barely stable, all the way to stable under any practical circumstances.

So I don't doubt airgun1 when he says some 1-12 twists shoot the 69 SMK. Sometimes all the factors run the same direction, e.g. higher velocity, hotter day, higher elevation.

SmokinJ, I haven't shot the 63 Sierra but it measures 0.775" so should easily stabilize in a 1-12 .223, and be "on the bubble" in a 1-14 .22-250.

cobrad, the 52 A-Max in a .22-250 would likely have an MV of around 3,800+ fps. In a 1-14 twist it should be somewhere in the range of "barely stable" to comfortably stable depending on elevation and temperature.

Another example, the Hornady 75 A-Max at 2,800 fps shoots brilliantly in my .223s with 1-9 twist. 1-9 is just a bit slow, a 1-8 is generally recommended for this bullet, but for my circumstances it works.

However all my shooting with it has been in relatively warm weather, say 60F and up. If I were to take it out after coyotes at =20F it likely wouldn't stabilize.

I once had the opportunity to talk with Eugene Stoner about the development of the M16. The original 1-14 twist, he said, was deliberately chosen because it was a "barely stable" twist.

Stoner said he was told to find a way to make a 55 gr. FMJ, .224" bullet effective in combat. The only way he knew, he said, was to make it just barely stable in flight, so it would immediately destabilize and tumble at the slightest impact.

The Berger bullet web site has a twist calculator that lets you play with the numbers a bit. JBM ballistics has good chart of bullet lengths.

I can tell you one bullet that won't work in a 1:12" twist barrel

The Green Tip "SS109" military bullet.

Out of the barrel of my Remington 700VSSF which is typically a 1/2MOA or better rifle I could spend the afternoon shooting at the dead center of a 4foot square of plywood and miss it every single time.

with 50grain Blitz Kings I can shoot a golf ball precisely enough to either "slice" the golf ball left or right, put top spin on it, drive it more or less straight down the range.

I'd say that as a general rule of thumb you should be ok up to 55 grains , but as others have noted, bullet length is what really matters.

Dave, My friend's gun was a Rem 700 1:12 twist, laminated HB 223. He lives at about the same altitude as you and we are in northern PA. He shoots year round, deer with it in the winter and crows, coyotes and 500 yard targets all year. The load 22.5 gns of H-335 with the 69gn SMK, LC or Win cases, Win WSR primers. They also shot well out of my Colt SP1 AR-15.

I called Sierra and they said that they weren't surprized that the 69 gn SMK worked well in a lot of 1:12 barrels, hence my comment as to I don't know why, as it surely shouldn't by rights. Some barrels are a little faster or slower than advertised twist. I knew that was true with button cut rifling; I don't know what type of rifling Rem uses on the various models.

The 63 gn Sierra soft point usually is a no brainer in a 1:12 as it is a short stubby things.

quote:

Originally posted by airgun1:
Dave, My friend's gun was a Rem 700 1:12 twist, laminated HB 223. He lives at about the same altitude as you and we are in northern PA. He shoots year round, deer with it in the winter and crows, coyotes and 500 yard targets all year. The load 22.5 gns of H-335 with the 69gn SMK, LC or Win cases, Win WSR primers. They also shot well out of my Colt SP1 AR-15.

I called Sierra and they said that they weren't surprized that the 69 gn SMK worked well in a lot of 1:12 barrels, hence my comment as to I don't know why, as it surely shouldn't by rights. Some barrels are a little faster or slower than advertised twist. I knew that was true with button cut rifling; I don't know what type of rifling Rem uses on the various models.

The 63 gn Sierra soft point usually is a no brainer in a 1:12 as it is a short stubby things.

That load is very mild. The max for that bullet on Hodgdon's website is 24.0 grains. Just saying. One doesn't have to shoot with the peddle to the metal all the time.

airgun1, thanks for the information. I ran the numbers again on the twist calculator at the Berger Bullets site: 69 gr. SMK, 0.900" long, 1-12 twist, 2,850 fps., 65F at 2,000 feet elevation.

The result is what they call a "stability factor". They say if the factor is below 1 the bullet will not stabilize; between 1 and 1.4 they call "marginal stability". For stability under all practical conditions they suggest a factor of 1.5 or higher.

The stability factor for the numbers I used works out to 1.02, meaning it is barely into the "marginal stability" range. I guess this is why it works in some rifles and not others.

The SS109 62 gr. military bullet measures 0.907" according to the JBM bullet chart. Using the same data assumptions as for the Sierra bullet the stability factor is exactly 1, so Allan DeGroot's experience is not surprising.

This link will get you to a photo of the target I shot with my 700 1-12 and 69 SMKs, with all three of the shots fired going through sideways at 25 yard (bottom of page 75).

http://fmgpublications.ipaperu...tions/GUNS/GUNS0812/

Getting back to the original question, bullet lengths of 0.75" to 0.80" should reliably stabilize in 1-12. As your friend's experience shows bullets even at 0.900" might stabilize, it's worth a try.

My own policy is to use my 1-12 .223s primarily as prairie dog rifles using 40 gr. bullets. For longer range fun I love that 75 A-Max in a 1-9 or 1-8 twist.

Actually with a stability factor from the Berger formula of 1.19 with 1-9 twist it too is in the marginal range. A 1-8 twist would get it to a solid 1.5 stability factor.

I wish Hodgden published 5.56 loads like Ramshot does. I'm using 24 gr. H335 with the 69 gr. Noslers, but thinking I would like to push them a little harder.
Just ordered 1000 more of these bullets. Natchez had them in stock last night.

Just as it is not weight alone which determines how much twist may be required for stability, it is not length alone, either.

The Center of Gravity (CG) of the bullet, along with other factors like the shape of the nose and the base, can also influence stability.

It has become fashionable to blame twist that is "too slow" for a lot of accuracy problems. This is not necessarily the case. I've seen two rifles with identical twists, one of which would stabilize a bullet perfectly, and the other would frequently turn it sideways through the paper.

By and large, conventional cup-and-core spitzer bullets of 60 grains and under will stabilize just fine in a 1-14" twist. Blunter bullets of heavier weights like the Sierra 63 grain semi-point and the WW 64 grain Power Point are short enough and have a CG that allows them to also stabilize in most 1-14" barrels. I've had no trouble, either, with the Nosler 60-grain partition in a 1-14" .223.

In the case that you make the bullet longer with a long hollow point or plastic tip and at the same time move the CG rearward you will need increasingly faster twists to stabilize such bullets.

So, don't automatically assume that you need a faster twist for a particular bullet until you've actually shot that bullet in your particular rifle to see what the results are.

These guys have given you good advice. The one point I wanted to bring up is that length and weight are a good indicator but look at the bearing surface. Some "long" bullets have less bearing surface than others. I've found that I can get great accuracy with flat based bullets that are heavy but shaped different than some of the long bt that have less or the same weight but have more bearing surface. My .22-250 will shoot 64gr flat based Win but won't shoot the 69gr Nosler target bullets as well. It loves 40gr. up to 52's or 53's great. Above that is hit & miss. My .223 goes higher but it's 2" faster twist.