.223 twist rates?

[TEC]

Looking at .223 bolt action varmint rifles and in particular, the CZ-527 Varmint vs. Savage 12-series models. I am drawn to the CZ with the laminate stock, but see the spec of 1:12 twist vs the CZ with kevlar stock w/ 1:9 twist, same as the Savage w/1:9 twist.

The bulk of my .223 is 55 grain FMJBT. I have a small amount of 64 gr soft-point and 70 gr soft point which could be used for deer, but my interest here is to have an accurate bolt action rifle in something other than rim fire that I can actually shoot for fun without breaking the bank. So, given that the rifle will be used for target and small varmint hunting almost exclusively, should I go with the 1:12 or the 1:9? From what I read, the 1:12 is deadly accurate for the 55 gr FMJBT but isn't sufficient to stabilize heavier rounds. Is the 1:12 better for 55 gr?

 

[PAPACHUCK]

The 1:9 should serve you well. If you were to stick with ultra light bullets, then go 1:12, but the 1:9 will do 45gr-62gr just fine.

 

[dagger dog]

The 1-12 will stabilize the 55's or under just fine but if you are going to use up those 64and 70 gr soft points they may not stabilize. I depends on the length and design of the bullet, and some what on the gun .

Rule of thumb when in doubt go for the faster twist.

I own a 12FV 1-9 Savage , it shoots the 55 gr class under an inch at 100 and it will shoot 40 gr VMax the same. But it can also shoot the Sierra 69 Matchkings into 1 1/2" groups at 200.

 

[TEC]

Twist rates

Thanks all. I suppose it is possible that CZ is now making some of the newer 527 .223 with the faster twist rate in something other than the kevlar stock, but the only one listed 1:9 is the kevlar stock, not the laminate. Suppose there are advantages to the kevlar as well, but the old fashioned, traditional firearm part of me is drawn to the wood and shiny metal of the laminate version. By "drawn to", this means that I am desperately trying and only temporarily restraining myself from running right out and buying the first CZ-527 varmint I can lay my hands on, though.

 

[TeamRush]

Light MASS bullets (Mass = Weight),
And short 'Bearing' sides on Light weight bullets will sheer off with very fast rifling, making the bullets wild 'stingers'...

The LONGER (Rifling contact 'Bearing' area) and the HEAVIER the bullet, the faster you can spin it.
Long, heavy bullets like FAST barrels,
And larger bullets move from chamber to muzzle SLOWER than light weight bullets (more mass means slower acceleration).

Slower bullets also 'Grab' faster rifling better than smaller, lighter, faster moving 'Varmint' bullets do.
.....................................................


While lighter, shorter 'Varmint' bullets like a slower rifle twist so they can can stay in contact with the rifling better.

Lighter weight 'Varmint' bullets are shorter, have less 'Bearing' contact area, and they move Faster from chamber to muzzle since they have less weight to get moving down the barrel.
All this means if you try and push a light weight bullet down a fast twisting barrel,
All you are going to succed in doing is one of two things,

Either you are going to spin the light bullet so fast it flies apart when it exits the muzzle,
(not as common with todays hard copper alloy jacketed bullets as it used to be with lead bullets)
OR,
You are going to strip the copper off the outside of the bullet, deforming it and not getting the spin you want at all.

For long, heavy bullets, you can go up to 1-9 (1 twist in 9 inches of barrel travel) or even 1-7 twist.

For bullets around 55 to 62 Grains, I prefer a barrel between 1-12" to 1-9"...

For REALLY FAST and light weight bullets, 40 or 45 grain,
I prefer a barrel with SLOW rifling, around 1-12" or 1-13".

I have a Ruger M-77 MkII that LOVES the light weight, cheap factory 45 grain rounds, and it's a 1-12" barrel (pretty standard for most factory barrels.

My AR service match rifles have either 1-9" or 1-8" barrels, and we shoot heavy, FMJ ammo in them.

My LONG RANGE AR has a 1-7" barrel, and it normally sees 80 to 90 grain bullets, and does very well with them,
BUT,
The heavy bullets mean you have to hand load each round,
And the chamber has to be Throated for those extra long rounds that WILL NOT fit in the mags...

So, if you want a 'General Shooter' that will feed and function from a mag, then I suggest around 1-10" or 1-12".

If you are going 'Varmint' smacking with very light rounds (40 grains or so) then try a slower rifling, around 1-12" or slower.

My light loads start doing silly things around 1-9", so if you go lower than 1-9" twist rate, expect to have some fliers with the short, light bullets...

 

[TEC]

TeamRush:

Thanks, that makes good sense. The ammo I am buy in bulk is the UMC 55 gr metal case .223 Rem. I don't hand load, and I will primarily be punching paper, but not competitively, as well as plinking and occasional varmint shooting.

So it sounds like the CZ 527 Varmint Laminate w/ 1:12 in twist will indeed serve just fine. And if I understand correctly, it is better to under-spin the occasional heavier round I might be shooting and sacrifice a bit of accuracy in that situation than it is to consistently over-spin the light, copper jacketed 55 gr rounds that will be the bulk of my shooting, both sacrificing some potential accuracy and tending to more quickly foul the barrel with build up from the metal jackets. Correct?

 

[loadedround]

From past experience, a 1/9 twist rate.

 

[rcmodel]

If all you want to do is shoot 55 grain bullets or lighter, 1:12 is great.

My 1:12 Colt CAR-15 and CZ-527 both do well with everything up to 63 grain semi-pointed. They really like 55 grain Nosler Ballistic-Tips or Hornady V-Max though.

For varmint hunting, the 50 grain bullet is the flattest shooting .223 load bar none.

rc

 

[TeamRush]

TeamRush:

Thanks, that makes good sense. The ammo I am buy in bulk is the UMC 55 gr metal case .223 Rem. I don't hand load, and I will primarily be punching paper, but not competitively, as well as plinking and occasional varmint shooting.

So it sounds like the CZ 527 Varmint Laminate w/ 1:12 in twist will indeed serve just fine. And if I understand correctly, it is better to under-spin the occasional heavier round I might be shooting and sacrifice a bit of accuracy in that situation than it is to consistently over-spin the light, copper jacketed 55 gr rounds that will be the bulk of my shooting, both sacrificing some potential accuracy and tending to more quickly foul the barrel with build up from the metal jackets. Correct?

My 1 turn in 12" barrels ALL like about anything under 65 grains...
You go over 65 or 69 grains, you will start to see the accuracy suffer,

But all in all, anywhere between 40 grains and 55 grains the 1-12" is just GREAT for plinking and with the 'Right' ammo, will do MOA accuracy with ease.

I have a good friend with CZ .223 rifle, and it's probably more accurate than the .223 Ruger I like to shoot most.
Very nice rifle, well made, accurate, and LOVES the cheap factory ammo!

-----------------------------------
I want to give you a word of warning about using military surplus 5.56x45mm NATO ammo in your CZ bolt rifle...
Military 5.56 is 'Hotter' than .223 Remington ammo,
And no matter what the 'Experts' tell you,
Military/NATO 5.56 IS NOT .223 Remington!
Different tolerances, different case, different muzzle velocities, different bullets...

Military ammo uses 'Hotter' powder, meaning the chamber pressure is going to be higher than the 'Hottest' SAAMI recommended load.
http://www.saami.org/

Military ammo uses a different neck length to the case than .223 Remington. It's slight, but can create freebore problems.

Military ammo uses much harder copper alloy on the jackets,
Especially foreign import ammo which is VERY HARD, and can work over your rifling very quickly.

Since you have a VERY nice rifle that is also Accurate from the factory, I just thought I'd bring that to your attention.

You probably won't have any chamber failures or barrel failures,
But excessive chamber pressures CAN oversize the chamber, expand the barrel throat, ball powders especially will erode the barrel throat,
And you might have bolt operation and ejection problems from the greater than designed for chamber pressures.

Not trying to scare you, since I don't think the rifle will 'FAIL'...
I just think that shooting military surplus or those imported rounds are hard on any finely made rifle!
-----------------------------------------------
------------------------------------------------

Remember, the most important thing is barrel break-in to accuracy!

Don't worry about what you have been told by 'Experts'...
Clean the crap out of what ever barrel you have, no matter how old,

I often plug one end, and fill the ENTIRE barrel, chamber to muzzle, with copper solvent and let it stand overnight...
You won't BELIEVE the crap that comes out of some barrels!

Then clean it REALLY WELL everyday for a week or so,
Until you stop getting 'Green' on the patches when you use ammonia based copper cleaners...
(and remember, it often takes an hour or more for the 'Green' or 'Blue' to show up on patches!
You aren't just going to push them through and get 'Green' right away!)

Clean the CRAP out of that barrel,
Then fire ONE shot,
Clean the crap out of it again,
Fire ONE shot,
Clean the crap out of it again,
Fire ONE shot....

Repeat about 10 or 20 times...

What you are doing is 'Burnishing' the barrel.

When you machine a barrel, it gets all kinds of scratches, nicks, chatter marks from the cutting tools, ect.

Copper (or in some cases, Lead) collects in those low spots and works like a 'Hydraulic' medium, protecting the gouge or scratch, while keeping the rest of the barrel metal from 'Smearing' into the edges and filling the holes up.

If you properly 'Fire/Clean/Fire/Clean' the barrel,
The edges of those scratches will soften and round over, and not gouge up the bullet as much.

With new barrels, it's CRITICAL to break in the barrel by firing/cleaning it.
The 'burrs' and gouges on the edges of the rifling will cause problems.
Burrs imbed in the bullet, then scratch the barrel all the way out.
Gouges and chatter marks will first de-breed of sharp edges as they brake off in the soft copper jackets, and do harm to the barrel,
Then the gouges will take 'Bites' out of the bullets after there are no more burrs or chips to send down the barrel.

Great cleaning will carry off many of the larger, looser chips and burrs,
And fire/clean will get the rest out with Minimum damage.
--------------------

If the barrel has already been used (as in used rifle),
You can still clean out ALL the copper/lead,
Then follow barrel break-in procedures (shoot/clean/shoot/clean) and that will help 'Burnish' and wear down the 'Hydraulic' pockets of copper... And actually wear down (Smear) the metal edges and fill in some of the low spots/chatter marks/scratches, ect.

Shoot/clean about 10 or 20 rounds,
Then shoot 2 rounds, clean, shoot 2 more rounds, clean, ect for about another 20 or so rounds...

You will find at the end of the 'Break-In' procedure you can get the barrel clean with one brushing and about three or four patches!

I don't know about you, but the easier cleaning through out the life of the rifle is worth a day breaking in a barrel for me!
Not to mention I have NEVER seen a barrel that didn't get more accurate, no matter how old the firearm...
----------------------------------------

There are some 'Fire Lapping' kits out there,
Where you introduce an abrasive to the bullets to 'Scrub' or 'Sand' away stuff in the barrel...
DO NOT USE THOSE!

You can REALLY screw a barrel up with those fire lapping kits if you don't know EXACTLY what you are doing!

Fire lapping *CAN* make your rifle more accurate...
*IF* you have VERY SPECIFIC problems!
Most of the time, they just oversize the bore, and wear down the rifling to a point the barrel is useless!

 

[Wesson Smith]

Nice info about burnishing a barrel, but way too much work IMO.

 

[Jim Watson]

A little history about .22 centerfire rifling twist rates.
For years and years before the Air Force and Army got into it, the standard twist was 14" which does very well for 50-55 grain flatbase spitzer varmint bullets and 52 grain boattail match bullets. The original military projectile was a 55 grain boattail spitzer FMJ, which makes up into a longer bullet due to the shape and thick copper jacket. They found that those bullets were not stable in cold dense air and increased the twist to 12" because they had to figure on combat in Alaska and Siberia.

The first I saw about faster twists was when the USMC determined to shoot the M16 in Service Rifle matches instead of the then-common accurized M1 or M14. They used 10" twist barrels for better accuracy from military ball ammunition. They were soon replaced by 9" twist barrels for real match ammo with 69 grain Sierra Match Kings. That was the status quo for several years until the M16A2 came out for the SS109-M855 ammo that NATO specified. A 9" twist is fine for that, but the companion SS110-M856 tracer is a very long bullet and called for a 7" twist. The target shooters soon picked up on that and now use 7.5-8" twists for 77 and 80 grain bullets. I have a 6.5" twist for 90 grain bullets but that may be overkill.

In your stated application, a 12" twist will be fine. I think "deadly accurate" with bulk 55 gr econo-ball is kind of a misnomer, but you might get lucky. It won't do much with 62 grain "green tip" M855, though. The Sierra 63 grain semipointed and Speer 70 grain roundnose are old designs meant to run in slower twists, my 14" twist .22-250 shoots the Speer well enough for smallbore deer hunting to 200 yards.