Don’t know if you have the manual but it should specify the proper weight. I have a Savage 12 LPVR with a 1 in 7 twist and my manual recommends 69 gr and heavier bullet weights. It shoots 75 gr Hornady BTHP at 1/3 MOA at 100, 200 and 300 yards. It absolutely hates 55 gr which I only shoot when I want to check I’m on target…

 

1 in 8 should work fine with 69 and over. 55 and under would be a clear case of over stabilization. That being said there are quite a few other variables involved also.

 

Both of my M16A1's with 1 in 12 twist love the 55 gr, but that is what they were designed to shoot.

 

I myself would definitely stick with 62 & 64 grain for 1/8.
I strictly use it for my 1/7 s , but they are good for 75g all day .
The 75s are just too expensive for me .
Precision wise , black hills makes a 68 or 69 boat tail .
This is very accurate, but it too is expensive.
Oh , and accuracy wise , green tip is good value and weight, but not very accurate compared to others . My favorite value for paper is Federal AE223N , or Hornady BLACK - both 62g.

 

My Bill Wylde match rifle with an eight twist Krieger was surprisingly accurate with bullet weights up to and including 80 grains. The Sierra Match King bullets are used almost exclusively at Camp Perry.
Remember that muzzle velocity has a lot to do with stabilizing bullets. My service rifle that he built with a 20 inch barrel is one turn in 7.8 inches. I have the data and awards to back this up.

 

My Match and long range shooter buddy uses 52 grain Sierra Match King for 100 yards, 62 grain Match King for everything else except 80 grain Match King for 600 yards National Match and F-Class.

He keeps careful records including actual targets, and he's showed me 100 and 200 yard prone targets with scope that were literally a single .22 to .25 caliber hole.

 

Thanks to all who replied, I'll find some heavier loads. Had been shooting 55 and 62 grain, now want to see how the heavier ones will shoot in a bolt gun

 

I have had good luck in my Remington 700 223 with the heavier bullets but I have forgotten what my rate of twist is. I may have to put some tape on the cleaning rod and recheck that.

 

8 twist barrel in .223 will shoot all bullet weights up to 80 grain. There is no “correct” bullet weight for any particular barrel twist. All will shoot a range of bullet weights. In general, faster twist rates will stabilize heavier bullets in a particular caliber, slower twist rates work best with lighter weight bullets. There are situations where faster twist barrels will “overspin” light bullets and cause them to disintegrate in flight. This usually happens when trying to shoot thin jacketed light weight bullets at very high velocities in fast twist barrels. On the other hand, trying to shoot a long, heavy bullet in a slow twist barrel will create a situation in which the bullet is not properly stabilized and will not shoot accurately. At longer ranges the bullets will actually become so unstable that they will precess and come through the target in a “keyhole” fashion.

I have shot 8 twist barrels in all my competition rifles from AR-15 service rifles to bolt actions and from many different barrel makers. They have handled bullet weights from 52 to 80 grain with excellent results. I tend to shoot bullets in the 69 to 80 grain range most often but if I see a great deal on the 50-52 grain bullets I will buy them and use them for offhand practice. My “go-to” load for .223 is the Sierra 69 gr Match King, LC brass, 25 gr Varget, Rem 7-1/2 primer (or whatever else I have). So far this load has shot consistently excellent groups and scores in every rifle I put it through.

Ultimately, you will have to try different combinations to see what works best in your rifle. Fortunately, the .223 is very easy to load for and it is not difficult to get great results with different loadings. Sorry for the long post. Good luck and have fun shooting it.

 

My buddy told me of a case of a shooter not getting hits at all on target and couldn't figure it out.
He watched and saw puffs of smoke about 25 yards down range.

The light bullets in a fast twist barrel were disintegrating from extreme centrifugal force and literally flying apart.

 

Yes, I have seen this happen several times over the years and have had it happen to me as well. The lead core becomes soft from the extreme heat generated and loses its form, the loose jacket comes apart under the tremendous centrifugal force and the bullet “blows up”. It appears as a blue-gray puff of smoke along the bullets’ flight path to the target.

In my case I was trying some 6mm benchrest type flat base bullets in a 6mm HAGAR rifle. I had bought them at a good price from an online forum and was looking to use them at 200 yards. I don’t remember what type of jackets they used but they definitely were not suitable for my purposes as they were coming apart in flight rather frequently.

 

Sierra bullets do not blow.

 

I can’t say with 100% certainty that this is true but I will say that I have never had an issue with Sierra bullets in the many thousands that I have shot. Of course, I haven’t really attempted to push them outside of their recommended velocity ranges or twist rates.
They are certainly a very high quality product. I like the 80 grain Sierra bullet for 600 yard shooting. It’s easy to load for and not overly sensitive to seating depth. It will take a pretty good jump and still shoot accurately.
At the extreme end is this Sierra .224 diameter 90 grain bullet. It requires a 6.5” twist barrel to properly stabilize. Shoot these at velocities of 2750+ and your barrel life will not be long!

 

I have a N.Dak redeck “friend” who swore by his 17 Remington and what it would kill. And I got to see him kill all types of varmits, he probably dropped a deer when no one was looking. His budget needed him to reload to shoot his 17 Remington much. His first loads wouldn’t even print on the paper at 50 yards. Finally at 10 yards, it appeared like a shotgun blast on the paper. His max load with the 25 grain hollow point was coming apart right outside the barrel, when he reduced the load, it’s accuracy re appeared. So it’s very true that some lightweight bullets and fast twist, don’t mix.

 

For right now I don't have a 1/8 twist barrel but mostly mine are 1/7 two are a 20" barrel A2/ A4 and I have 5 with 1/7 16" carbine barrels (uppers), all 5.56 NATO chambered.

My best groupings are from heavier Hornady TAP 75 gr and Sierra SMK 77 gr match type ammo, maybe try these and even some 69 gr bullets to find out what your barrel likes best (best accuracy).

 

Another thing about loading the heavier bullets would be the OAL to fit in the magazine, shouldn’t be a problem with factory loads though.

 

This is true of the long ogive bullets such as the Sierra 80, VLD types etc. The Sierra 77 , Nosler 77, Hornady 75 grain and similar HPBT bullets are designed to be loaded to magazine length.
These are the types of bullets that you will find in factory loaded ammunition
This photo will clearly illustrate the differences in bullet length, length of bearing surface, and length and shape of ogive between the 77 Sierra and 80 Sierra bullets.

 

Mine shoots 55gr and 75gr very well