Discussion in '6BR, 6BR Improved & Wildcats' started by chadwickz71, Aug 21, 2017.
Altitude plays a role in factoring twist rates.
It certainly does
Fine .....what would the altitude have to be to make a 55 grain Nosler ballistic tip show stable in 1 and 14 twist Barrel and then get back to me.
Are there any altitude/twist rate charts that show the impact on accuracy? I can see the need for the normal adjustment of the powder charge or a barrel tuner.
As does humidity.
One of the problems with asking "what twist rate works the best" for a given bullet on a worldwide forum is that the responses are not quantified. In other words, what works great for a guy in arid Arizona may not be optimum for a guy shooting the same bullet in Florida.
I tend to agree with 4Xforfun that with custom barrels, we tend to go with ever increasing twist rates in order to achieve high SG numbers. This is partly due to the fact that bullet weights and lengths seem to be always increasing. Thus the requirement for faster twist rates for optimum bullet stability. At least we're not into turns in fractions of an inch - yet!
Chapter 1 in Volume I of Bryan Litz's book Modern Advancements In Long Range Shooting dispels the myth that fast twist rates reduce muzzle velocity to a significant degree. Given that, the prevailing philosophy seems to be “the faster the twist the better” – as long as the bullet doesn’t fly apart.
My 2¢ worth.
I didn't ask what twist rate...I asked at what altitude does a 1-14 twist become stable with the 55 NBT (length of .815).
well Tod, here @ 350' above sea level, a .224 55gr Nolser, will keyhole @ 100 yds. , with a 222 rifle.
Again...maybe yes..maybe no. We must have 10,000 55 nbt's down range here at 900 feet ASL that shot perfect in 14 twist tubes. Then one day we had a new 22-250 AI that put them straight sideways at 25 yards. I was confused so I ran them in the Berger Twist Calculator. .75ish.
We were obviously doing it wrong all those years, and finally got it right when they started to keyhole!!
Like I said.....run the 215 hybrid at 3000 with an 11 and run a 200 hybrid at 2900 in a 12 twist. Both come in at around 1.2. Both shoot VERY SMALL at 1000 yards in COMP.
Like I said...you can't live your life based on what the Berger calc says.
Agree to disagree
It gives you a place to start Depending on your location, and places to shoot. one must fine tune for the conditions
maybe yes...maybe no.--- I opt for the faster & HV contour for making weight.
Just don't add too much weight to the stock
I agree...if I am building xyz and plan on shooting abc bullet I would cirtianly take a look at the calculator. I didn't plan on shooting the 215 in the 11 twist as it didn't exist, but tried it !! Same with the 200 Hybrid and the 12 twist...my plan was to shoot the 187 BIB flat base. It didn't shoot for crap. Tried the 200 HB and instant winner!!
I shot 215's just fine out of a .300 Win Mag 11" twist...I do use 10" twists now and have a 9" twist ready to be chambered.
Yep...I've got 10's, 11's, and 12's in both 300 WSM and WBY. We will see if the new "heavy weight" 30 cal comes out...may need to look at a 9.5 or 9.0 twist.
Well this may help as a reference. My friend has a 22-250 that will shoot the 53gr vmax into .25" groups here in Colorado at 6500' elevation and at his home range near Minneapolis MN the exact same rifle and load key holes at 100 yards and is about 2" groups. His barrel is a factory Remington 1:14". This has been repeated every fall for several years now.
I put a 28" 1-7.8tw Dasher bbl in hvy Palma contour on my trued M700 in a Shehane Tracker stock this summer, and have had excellent results out of it with Berger 105 Hybrids. A hvy Palma of this length weighs a bit under 6.5lbs, and balances nicely on the rest & rear bag w/o any extra weight in the butt of the stock. Haven't weighed the complete rifle w/Sightron SIII 8-32x56 scope, but based on similar rifles of mine, I'm guessing it's just over 14lbs.
If you use the full contour barrel you will need to weight the butt to get it to balance in front of the lug. you will end up in the neighborhood of 22 pounds. Takes longer to heat up and longer to cool down. An HV barrel will do what you want it to do also. You said you weren't going to compete with this rifle but resale should always be on your mind. There are no IBS or NBRSA long range matches in Texas and probably never will be.
But you will have a larger audience to sell to on the interweb if you make it 17lb legal light gun. A light gun rifle can be shot in Light and Heavy class.
You are missing out on a lot of fun not shooting matches in Texas. There are lots of non-registered matches that are highly competitive and loads of fun in Texas. Don't let the non-registered part fool you, to win a clay break, poker chip, or Fly Shoot in Texas you better have the equipment and know how to drive it.
A 1.250 tapering to 1.050 at the muzzle is a good compromise between no taper and HV and the 1.050 looks great with less weight. I have one and Tim Claunch has me another on order from Brux
I'm assuming you mean 1.250" to 1.050" at the muzzle?
Hoodoo, yes, I was posting from my phone. I should have proof read it.
1.250 to 1.050
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