best bullet weight for 10 twist 600 yard target

K

kenjmcd

Inactive
I have a 308 22 inch barrel and 30.06 22.5 inch barrel and both have a twist rate of 10. I have 168 grain sierra match TMK bullets, but not sure if this is the best weight for a 600 yard accurate target.

I am looking to make the best bullet for the shot, and expect to make changes on the path there. looking for the most consistent bullet for 30 cal. with 10 twist to hit at 600 yards.

Does someone know if this is ok, or would I be better off with a different weight ?

I am hoping to get into shooting this 600 yard a lot and it's going to be my primary bullet.

I am reloading my ammo, and someone mentioned that a 210 may be better with that twist rate of 10.

I have a ATN 5 - 20 power 4 K pro scope, and so I have everything I need to make them - just need to find the best bullet weight and powder amount

Thank you for your help
Ken
203-605-1633
 
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When I was shooting an M1A in high power I shot SMK 168s at 600 and they did fine in a 1:10 Krieger barrel. Don't know about the TMKs, but I expect they'd be good also.

Tim
 
My experience shows 175 to 180 grain bullets typically shoot more accurate in those conditions. 190's in a 22 inch 30-06 1:10 twist will also be very good.

190's in 12 inch twist 308 Winchester barrels 24 inches long won lots of matches.

Bullets need not to be spun too fast for best accuracy. Good example is 7.62 NATO M80 ball ammo's 147 grain bullets usually shot most accurate at long ranges from 1:13 or 1:14 twist barrels leaving about 3000 fps.
 
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If you have 168s, shoot 168s. You need the practice anyhow. (We all do.)
Then restock with something heavier.
I was never a very advanced mid or long range shooter and was very happy at 175. My Master friend is up around 208 now.
 
just starting reloading again. I have not reloaded since 1980, and that was a 44 mag ( Ruger Super Black Hawk.
I have all new everything except for the rifles.
 
The "best" bullet can be tricky to chase. First, stability is more strongly influenced by bullet length than weight. You can "check out" bullets with a stability estimator like this one. The result it gives you is a number called the gyroscopic stability factor. A lot of folks target a value of 1.5 as optimal. Sierra told me years ago to use a range of 1.4 to 1.7 for best match accuracy, so the numbers don't need to be dead exact. With a 10" twist, a lot of bullets commonly used, like the 168-grain SMK, are at a higher G.S. number than that range, but still, shoot very well up to a point. The 168-grain SMK, in particular, can become dynamically unstable below 1400 fps and start to tumble beyond 700 yards when a 10" twist is used. The 175-grain SMK does not do that, and neither do the heavier Sierra target bullets. Anyway, use the stability factor estimator to screen your candidates, and I think you will do alright. You may want to measure your barrel's exact twist to tighten the estimates further.
 
If memory holds, the Sierra 168 TMK has significantly better bc than the 168 sierra hpbt. The tipped version seems to carry noticeably better than the hpbt version at 600 yds, but may need to be seated shorter in most/some rifles. Have one rifle with longer mag and extended throat, and can use the the tmk seated kinda out well beyond standard max col.

Am tempted to say just try it out, but keep forgetting that it is tougher to get access to 600 yd range for some.
 
Sierra's 30 caliber 168 grain HPMK's have the reverse situation as their 180 grain HPMK.

180's originally had a long 9 degree boattail. A favorite for rebulleting 30-06 M72 and 7.62 M118 match ammo. Excellent accuracy through 1000 yards. In the 1980's, Sierra changed the boattail to that of their 168 HPMK; a shorter one with a 13 degree angle. These often went subsonic in rebulleted M118 match ammo at 1000 yards. The Army team contracted Sierra to make several thousand of the old style.

When the 7.62 M852 match ammo with 168 HPMK bullets replaced M118's 173 FMJBT, its bullet usually went subsonic before 1000 yards fired from M14NM rifles 22 inch 1:12 twist barrels but 1:11's were a little better. In 7.62 Garand 24 inch 1:12 twist barrels, those bullets usually stayed supersonic through 1000 leaving about 50 fps faster.

Sierra's new 30 caliber 168 grain TMK bullet has the same long, 9 degree boattail their original 180 grain HPMK had; so thinks me. Their 175 grain HPMK has the same boattail as the original 180 as Sierra partnered with Lake City arsenal to do so.
 
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I have a little experience with 168 gr SMK and TSMK in both 308 win and 30-06, but I rarely get out to 600 yards, so my observations may not apply to your goals. I use two different savage 308 rifles with 1 in 10 twist and a Remington 700 30-06 with a 1 in 10 twist.

Both shoot very well out to 400 yards for me, but the TSMK has less drift and slightly less drop in my experience. Accuracy is excellent for both of these bullets in my three rifles.
you already have the bullets- so load them up and send them downrange!
 
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