Twist rate
- Thread starter Fritz357
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rabid wombat
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More knowledgable people will follow - 1:12 vs 1:11 - no problem.
AJC1
Member
I'm guessing you know stability effects bc and understabilized bullets are bad. There are calculations to give you a number and you should do the numbers to find out....
How do i find these calculations
AJC1
Member
Wow hey thank you
Bcwitt
Member
I was to understand the 1-11 was made specifically for 168gr mk.
Archie
Member
With the thought of 'junk bullets' dismissed, as I don't think any of the major manufacturers knowingly sell 'junk bullets' the basic thought in my experience is a lot of overspin is not as harmful as a little under spin. Twist rate is more a range, or 'top' and 'bottom' rates than a specific point value.
If attempting to load for long range accuracy - like 1000 yard targets or such - one will find one brand of bullets and possible one type of propellent and sometimes case and primer make a difference. No real way to predetermine those factors. Trial and error seems to be the route (and take notes).
If attempting to load for long range accuracy - like 1000 yard targets or such - one will find one brand of bullets and possible one type of propellent and sometimes case and primer make a difference. No real way to predetermine those factors. Trial and error seems to be the route (and take notes).
JFrank
Member
1-12 is the minimum recommended twist rate for those bullets, therefore 1-11 is just fine.
Do i shoot strings through chrono first to find lowest es/sd then work on making them better or find most accurate load on paper then chrono it
I would chrono while shooting groups, comparing SD/ES vs group size.
You could also try the Satterlee method being you have a chronograph. Depending on the quality of brass, type of powder, and overall consistency, you can get on to what your load should be pretty quickly. I did my 6 Creedmoor load dev in 15 shots using it.
What I was referring to as junk. If fmjs. My experience has been he minimum rate of twist to stabilize produces ok groups. Much faster than necessary gives pitiful results on target.
Cup and core, bonded, etc didn't react like this.
Many thanks
Traditionally most 308's have come with 1:12 twist barrels and work well enough with most bullets up to 180 gr. It's actually bullet length, not weight so even some 200 gr bullets will work with a 1:12 twist. Many newer high BC bullets will be longer than old school bullets even if they are the same weight so some 180 gr bullets might be borderline in a 1:12 barrel.
The trend over the last few years is for target shooters to go to heavier (longer) bullets for long range work and many 308's are now coming with 1:10 twists. The 1:11 twist is just a compromise that should work better with some 180 gr bullets that might start becoming borderline with the traditional 1:12 barrels.
And just because a bullet is technically too long for the barrels twist doesn't mean it can't be used. Most of the time they are plenty accurate for 95% of shooters at real world ranges. The instability doesn't usually show up until you start shooting at pretty long range.
The trend over the last few years is for target shooters to go to heavier (longer) bullets for long range work and many 308's are now coming with 1:10 twists. The 1:11 twist is just a compromise that should work better with some 180 gr bullets that might start becoming borderline with the traditional 1:12 barrels.
And just because a bullet is technically too long for the barrels twist doesn't mean it can't be used. Most of the time they are plenty accurate for 95% of shooters at real world ranges. The instability doesn't usually show up until you start shooting at pretty long range.
Archie
Member
Okay. I didn't know exactly what that mean but I have bought and shot some really 'junky' bullets (I do my best to avoid them ever since). I presume the first sentence should end as '...junk are FMJs. I can't say my experience is completely the same. I have shot a good deal of 'pulled' U. S. military surplus bullets (.30 caliber in a couple weights) and do not recall any sort of problem. Never have used the .223 or 5.56mm bullets.
However, I have fired bullets of varying weights from the same rifle. The lighter bullets did as well as the heavier bullets; but I confess I never tried 'long range' target shooting. 600 yards at a thirty-six (more or less) bullseye was the most.
AJC1
Member
Lots of 1k shooting intention, not near as many 1k shooters. To be fair the numbers are increasing.
That's true. Some shooters are just trying to cheat the wind as much as possible. The farthest I shoot is 680. It's surprisingly easy when you have time to dial. It helps having a true long range shooter coaching you.
AJC1
Member
The furthest I've had the pleasure to shoot is 888 yards. I regularly shot 600 as part of steel varmint Silhouette, but now all I have is 300yds in my location...
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