bullets& barrel twist rate

[onebadeye]

Can anyone tell me the preferred bullet weight for1 in 8 twist 16" ar 15 in 223 cal.

[TonytheTiger]

All of them! That seems to be the most versatile twist rate that's more than happy to spin all the most common bullet weights up to 80 grains.

[kurtm]

I prefer 55 grain bullets in mine!

[onebadeye]

Thanks I have an assortment from 40gr to 69 gr.

[Alita]

You need to run the test. Buy as many different bullet weight and types you can, and simply shoot each for groups completely ignoring your zero. Which ever one groups the smallest and most consistent is the one your barrel likes. GENERALLY SPEAKING, tighter twist rate barrels like heavier bullets. My barrel is stamped 1/9 and loves 55gr and 75gr Hornady bullets.

[EkuJustice]

I would say the 40s would be pushing it with a 1/8 twist. Usually i would try and stick with 55 up and weight wist but a 50 probably wound t be an issue. the 40s MAY have issues but the only way to know is to try it in your barrel.

[pjb45]

I run a JP. I had hand loads with 69 gr SMK, Hornady Steel Match 50 or 55 and 75 grains, plus x193 military surplus stuff for bullets.

Plus a 100 yard zero in a concrete tube.

I did side by chromo and then pairs of targets at 200/300/400 yards. I compared the actual to the Swaro ballistic calculator.

I did my dope chart based on both sets of input. The Swaro calc was pretty much right on the money.

I got the same 100 yard accuracy out of each bullet type. Probably was the JP barrel more than me.

[dauntedfuture]

I have shot everything from 40g bullets to 82g in a 20" 1-8 service rifle barrel and a 12.5 1-7". so it can all be done with little detriment to accuracy. More has to do with bullet construction then weight: you can shoot a 40g BT bullet in a faster twist then you can a 40g SP bullet. If you over spin a bullet it can come apart. With the quality of barrels we are shooting you will see little difference in accuracy between a 55g bullet in a 1-12 and a 1-7 barrel. If we were shooting bench rest, yes there is a difference. light bullets in fast twist barrels are a common misconception and many NRA service rifle shooters find that a 52-53g Match bullet will outshoot their 69-80g match bullets on a 100yd reduced range and these are in 1-7 to 1-8 20" service rifle barrels (douglas, Krieger, Wilson etc.)

The "book" will tell you a 1-9 is good for up to 69g bullets but I have a 1-9 match rifle bolt gun that will shoot 80's great at 600. You will commonly find that you can get a 1-9 to shoot 77's at close range but they sometimes start to tumble at 600 yds.

[davsco]

I run a JP. I had hand loads with 69 gr SMK, Hornady Steel Match 50 or 55 and 75 grains, plus x193 military surplus stuff for bullets.

Plus a 100 yard zero in a concrete tube.

I did side by chromo and then pairs of targets at 200/300/400 yards. I compared the actual to the Swaro ballistic calculator.

I did my dope chart based on both sets of input. The Swaro calc was pretty much right on the money.

I got the same 100 yard accuracy out of each bullet type. Probably was the JP barrel more than me.

someone really did their homework, nice!

[Corey]

55s to 77s for 3gun will work. What do you like, what can you find, what's in your budget? Whatever fits those 3 questions ought to do ok for you.

[OscarMike]

Mess around, and figure it out! My stag 1:8 likes 55gr stuff the best, my satern 1:8 loves 77smk's, but I had a Sig DMR 1:10 that loved 75bthp's (1/4 moa gun... really).

[co-exprs]

Same from me. 55's to 77's. The sweet spot tends to be the 69's, but to be honest, I get the same practical accuracy with 55's from my 1:8 barrels. 55's are much cheaper than 69's and get it done just fine out to 600. Cheaper is always gooder than momoney.

[OscarMike]

Unfortunately my satern shoots 6inch groups at 100 with the 55gr rounds. But fortunately I get 0.6moa at 200yds out of 77's. This year I'll be ready for rm3g!

[TonytheTiger]

Unfortunately my satern shoots 6inch groups at 100 with the 55gr rounds. But fortunately I get 0.6moa at 200yds out of 77's. This year I'll be ready for rm3g!

How is this possible?

[OscarMike]

Don't know.... It's PMC ammo. I bought some more 55gr at cabelas yesterday to see if it's a 55 thing or a pmc thing.

My group at 200yds was almost a 1ft spread with the pmc. No bueno.

[openclassterror]

I would say the 40s would be pushing it with a 1/8 twist. Usually i would try and stick with 55 up and weight wist but a 50 probably wound t be an issue. the 40s MAY have issues but the only way to know is to try it in your barrel.

+1 Most 40gr bullets have thin varmint type jackets and cannot handle the rotational velocity of a fast-twist barrel. I had a bunch of Winchester 45gr JHP ammo advertised at 3600 fps. Out of my 7 twist barrel about 20% of the ammo would leave a gray streak in the air behind it. At 25 yards, 1" groups. At 50, 6" groups, keyholes, and lead spatter on the paper. At 100, many of the bullets had fragmented, and left little shotgun patterns of jacket material on the targets but no bullet hole. Here is the math-

3600 FPS x 12" per foot = 43,200 Inches per second

43,200 IPS / 7" per rev = 6,171 rev per second

6,171 rev/sec x 60 sec per minute = = 370,285 rev per minute

Let me say that again- 370,285 RPM!!!!!!!!! No wonder a jacket .005" thick with grooves deformed into it has trouble sticking together!