need help with barrel twist rate & bullet weight
what is good with light bullets and
what is good with heavy bullets..

Lighter bullets are slower twist.
From Sierra.
1 in 6.5" for 90 grain
1 in 7 or 8" for 77's + 80's
1 in 7 to 10 for 65 to 69
Not sure for the lighter bullets. My 1 in 8 will shoot 52's. 90's used to be listed as 1 in 7.

One of my .223 rifles has a 1-14" twist. I rebarreled it from a 22-250 barrel...it handles 55 grains and under just fine.

Probably most .223 rifles are made 1-12".....and that is what I'd pick to make a custom for the same bullets....55 grains and under.

I don't share the enthusiasm for heavier bullets in the .223....but there are those that do.

I happen to be one that does like heavy .224 caliber bullets. I've found Speer 70 gr. Semi-Spitzers shoot very well in my 1:12 twist barrels.

You need to kinda have an idea what you want the gun for. If you want to shoot the heavy stuff, get at least the 1:8" or faster so that you're covered there. 1:9" will usually top out around 69 grains. My opinion is if you're going to shoot the 69 grain ones you might as well shoot the 75 or 77 ones. If you want a more traditional varmint gun 1:12" is ideal, but as Vapodog noted the 1:14" with 55 grain and smaller.

LWD

CALIBERS & TWIST RATES by Lilja

http://www.riflebarrels.com/pr...iber_twist_rates.htm

1:7 or 1:8 are my choice. They will shoot 52 to 80 gns just fine.

1:9 would be my next choice. It probably won't work with 80's.

1:12 and 1:14 are ancient history in my book. They will work for 55 and below. Many 1:12's will stabilize 69 gn Sierra Matchkings.

General rule faster the twist the heavier bullet it stabilizes . My Bushmaster is 1:9 and does excellent with 52-77 grain .
As a matter of fact one of my Bushmasters stays inside a dime with 55-75 grains more times than not and of all powders it prefers BLC-2 so GO FIGURE !. Hell I can't get ANY of my bolt guns to do that with ANY BULLET OR POWDER on a consistent bases !.

PS ; I've never shot anything heavier than 77 so I don't know about 80-90 grain bullets .

http://www.bushmaster.com/comp...n_rifles.asp?cat=16R

Remember that you are dealing with obtaining some desired RPM's for stabilization.

Everyone here seems to be using numbers for a .223 Rem.

A .22 hornet requires a different twist than a .220 Swift.

If you give to fast a twist in a particular cartridge you will overstabilize and possibly have bullets disintegrate in flight.

You need to define what cartridge/desired velocity and what weight bullets you are using to make the solid recommendation you want.

quote:

Originally posted by Grumulkin:
I happen to be one that does like heavy .224 caliber bullets. I've found Speer 70 gr. Semi-Spitzers shoot very well in my 1:12 twist barrels.

70 grain speers shoot very well in my mini mark X. I think it's not just the weight but the bullet profile and velocity that will effect stability. As stated earlier, you can over stabilize a bullet and that's not good either. Another thing to remember is that the faster twists will generally create higher chamber pressures.

I think that we have over twisted the .223 rem. Granted it does have a large bullet weight selection much like that of the 06 but the 06 manages quite well within the 1 in 10 to 1 in 12 range. Yes, faster and slower twists do improve performance with specific bullets but they then become very specialized losing versatility.

I built a .223 AI with a 1 in 14 twist and shoot sub 45 grainers really fast so I can see the desire to go the other way but it all comes down to expectations.

Slower twist rates for shorter bullets, faster twist rates for longer bullets. That often works out as slower for lighter and faster for heavier, but not always. Especially if you're shooting lead free bullets.

I have shot and saw shot too many 223 bullets to say it is over twisted. 1:7 will shoot 52 gn SMK's into tiny groups @ 100 yards with no over stabilizing evident. 69 through 80 gn SMK's buck the wind like mad in 1:7 or 1:8 for 200-300 yards with 80's taking ovewr out 600.

I do draw the line at 1:7. This is not specialized. It does preclude the use of lightly constructed 40-45 gn bullets, but I don't use them anyway.

1:6.5 for 90 gn is specialized and not nearly as versatile as 1:7,8, or 9.

This is purely in 223.

I have not had luck with faster twists in 220 Swifts. I'll stick with 1:14 there with 52-55 gn bullets tops.

quote:

Originally posted by Captain Finlander:
I think that we have over twisted the .223 rem. Granted it does have a large bullet weight selection much like that of the 06 but the 06 manages quite well within the 1 in 10 to 1 in 12 range. Yes, faster and slower twists do improve performance with specific bullets but they then become very specialized losing versatility.

I built a .223 AI with a 1 in 14 twist and shoot sub 45 grainers really fast so I can see the desire to go the other way but it all comes down to expectations.

quote:

Originally posted by airgun1:
I have shot and saw shot too many 223 bullets to say it is over twisted. 1:7 will shoot 52 gn SMK's into tiny groups @ 100 yards with no over stabilizing evident.

I've had 52 gr. HPBT SMK bullets shed their jackets and do the "crazy chicken" in a 1-7" AR HBAR. It would shoot extremely tight groups but about 1 shot in every 4 or 5 shots went "missing".

We couldn't figure out what was happening because the effected bullets were clear off the target. But we then witnessed some hitting the dirt.

I'm sure this could have been avoided by backing off to about 3,000 fps and with the same bullet/rifle combo.

That said...... it's always better to error on the side of over stabilization than under stabilization.

I have only 1 of my .223s with 1-14". I use only short (flat based bullets) of 55 gr or less in that barrel.

Remember the 3 important factors for calculating the best twist in a caliber: 1. bullet weight 2. bullet length 3. velocity.

Bullet weight isn't the whole story.

Gremulkin can get good results in his 1-12" barrel with Speer 70 gr. Semi-Spitzers because that flat based bullet is extremely short for its' weight.

Twist isn't the only thing that contributes to blue streaking bullets. A rough throat will smoke them too.

I have a savage with 1in7 barrel I have shot thousands of 52grsmk's out of it and never had any trouble expect that they shoot very tight groups.

If thats a problem .

I perfer faster twist on all my rifles. Just in case I would like to shoot hevey for cailber bullets from them.

quote:

Originally posted by p dog shooter:
I have a savage with 1in7 barrel I have shot thousands of 52grsmk's out of it and never had any trouble expect that they shoot very tight groups.

If thats a problem .

I perfer faster twist on all my rifles. Just in case I would like to shoot hevey for cailber bullets from them.

And if your in California's beloved Condor Zone, you will need a tighter rate to shoot non-lead bullets. We have found a lot of guns that shoot lead standard for caliber bullet wieghts fine that just wont shoot same weight non-lead bullets worth a darn.

Tripletdad and guncurtis have valid points. I used weights from Sierra to define bullets but they are right that length not weight determine what twist is needed. Solid copper bullets will be long for weight. For the solid copper bullet a lighter bullet of about the same weight will stabilize the same but have a different zero at known distances.