223 Remington/Twist Rate/Bullet Weight Question
My Grandson has a Weatherby Vanguard Youth 223 Remington. The 20" barrel has a 1-12 twist rate. I have some 70 grain round nose Speer Hot Cor Bullets. Do you think there is any chance that this rifle will stablize these bullets? Since they are round nose I was thinking that they might since they are shorter than the spitzers. What do you think? I'm going to try loading some of them anyway so what should I look for, wide groups, keyhole marking on the target? Thanks for any opinions or information.
Q. What twist rate do I want for my rifle?
Probably 1:9, but it depends on what kind of bullets you intend to shoot.
Special purpose rifles often have uncommon twist rates. For example, if you are building a varmint rifle and want to shoot the short 35 grain, 40 grain, and 50 grain bullets, a 1:12, or even 1:14 twist would be best. On the other hand, long range High Power shooters often select 1:8, 1:7.7, 1:7, or 1:6.5-twist barrels to stabilize the long 77, 80 and even 90 grain bullets used for 1,000 yard competition. Additionally, new testing of heavier rounds (68-77 grains) seems to show that they perform very well in simulated tissue and may be a better defensive choice than 55 grain or 62 grain rounds. The majority of shooters, though, typically shoot bullets of 50 to 69 grains in weight (note that the 62gr SS-109/M855 bullet is as long as a 71 grain lead core bullet) and should select 1:9 twist barrels. At typical .223 velocities, a 1:9 twist will stabilize bullet lengths equivalent to lead-core bullets of 40 to 73 grains in weight.
1:12 twist rifles cannot stabilize SS-109/M855 bullets and 1:7 twist rifles are slightly less accurate with lighter bullets and will often blow apart the thin jackets of lightweight varmint bullets. The 1:7 twist is used by the military to stabilize the super-long L-110/M856 tracer bullet out to 800 yards, but unless your plans include shooting a significant amount of M856, the 1:9 twist rate is better suited for general use.
There is, of course, an exception: if you want to use loads utilizing the heavier, 75-77 grain match bullets currently used by Spec-Ops troops and other selected shooters, you'll want a 1:7 twist barrel. Although military loadings using these bullets are expensive and hard to get, some persistent folks have managed to obtain a supply, and will need the proper barrel twist to use them. Anyone who foresees a need to shoot this ammo should consider a 1:7 twist barrel.
Originally Posted by Sportdog
Speer has loads listed in the #12 manual for the 223. Their test gun had a 22" bbl with 1-12 twist. The highest velocity load is 27 grains of Winchester 748 (max) that yeilded 3068 fps. Starting load was 25 grains at 2824 fps. Good luck.
Originally Posted by Sportdog
Using the Greenhill Formula backwards it takes a maximum bullet length of just over 3/4" or less to stablize at 3000fps in a 1:12. I do not have a bullet to measure, but that should cover it if you can get it fast enough and it is short enough...
A quick length measurement of some bullets I've got laying around: No Speer .224
Win. 64 gr. 0.804"
Hor. 60 gr. 0.760"
Nos. 60 gr. Part. 0.790"
Barnes 62 gr. TSXBT 0.942" (1:7 to 1:9 twist rec.)