I just picked up a new Browning A Bolt Target rifle in 223. The twist rate is 1:8 however all the load data I have seen so far is for 1:12 twist, even for the heavier bullets up to 90gr. Does a different twist call for different loads? If so, is there a source of information specific to 1:8 twist? I have read that the faster twist might create higher pressures. Any comments you might have for me would be appreciated.
223 and 1:8 twist
- Thread starter Tozguy
- Start date
Tozguy, you need the 8 twist for 75 and 80 gr bullets. Some say a 9 twist will stabilize 75s but in my experience it is marginal. That is why my 30 inch MacLennon barrel has an 8 twist.
Of some importance is the freebore and throating in your .223 chamber. Unfortunately most reamers such as the Wylde are ground to produce a cartridge that fits the AR15 magazine. So you have to seat the 75s and 80s with the bearing base of the bullet below the donut. This prompts some shooters to work at pressures not meant for this cartridge in order to obtain unrealistic muzzle velocity.
There are a lot of different .223 reamers in particular wrt the angle of the leade. What you get in a factory bolt rifle is a roll of the dice. I have no experience with the Browning so cannot comment on that rifle. Perhaps other members of this forum have experience with this rifle.
Get an oal with the bullet just kissing the rifling and compare this to published data so you can estimate a starting load. For sure you want to use CCI 450 small rifle magnum primers because they can take the pressure. Varget, RL15 and H4895 are good powders. Keep velocities at 3000 for the 75s and 2900 for the 80s and you won`t be getting jets of gas in your face from pierced primers.
Of some importance is the freebore and throating in your .223 chamber. Unfortunately most reamers such as the Wylde are ground to produce a cartridge that fits the AR15 magazine. So you have to seat the 75s and 80s with the bearing base of the bullet below the donut. This prompts some shooters to work at pressures not meant for this cartridge in order to obtain unrealistic muzzle velocity.
There are a lot of different .223 reamers in particular wrt the angle of the leade. What you get in a factory bolt rifle is a roll of the dice. I have no experience with the Browning so cannot comment on that rifle. Perhaps other members of this forum have experience with this rifle.
Get an oal with the bullet just kissing the rifling and compare this to published data so you can estimate a starting load. For sure you want to use CCI 450 small rifle magnum primers because they can take the pressure. Varget, RL15 and H4895 are good powders. Keep velocities at 3000 for the 75s and 2900 for the 80s and you won`t be getting jets of gas in your face from pierced primers.
Your 1:8 twist is great for the heavier match bullets up to and including the 80 grain offerings from Sierra and Berger.
The 90 gr will usually require a 1:6.5 twist, although there are always those who claim to get good accuracy with 1:7 or 1:7.5.
Start the lower of the recommended loads, and slowly work up. Each rifle is a little different, and the use of molyed bullets will have an effect on powder charge.
The 90 gr will usually require a 1:6.5 twist, although there are always those who claim to get good accuracy with 1:7 or 1:7.5.
Start the lower of the recommended loads, and slowly work up. Each rifle is a little different, and the use of molyed bullets will have an effect on powder charge.
Thanks for your comments. One more question is how light can I go with a 1:8 twist? I have a heap of bullets in the 40 to 55 gr range that I would like to push using H322. I don't see a problem if I build the charge up gradually but just checking with you all in case there is a detail I missed.
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