sil9mm
Junior Member
Posts: 22 
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Post by sil9mm on Dec 31, 2017 12:55:33 GMT -8
I'm thinking of building a lightweight hunting ar in 6.5. I was looking at the TrueSporting's site and saw they have a 18" but 1x9 twist. I was hoping to shoot 140's. Will they stabilize just fine?
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sil9mm
Junior Member
Posts: 22
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Post by sil9mm on Dec 31, 2017 13:54:35 GMT -8
Also, what kind on velocites can i get with 140ish with an 18" ?
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Post by GLSHOOTER on Jan 2, 2018 6:49:46 GMT -8
I haven't played with them but I postulate around 2600.
These barrel seem to exhibit behavior implying they shoot one twist faster than you would expect. We shoot lots of boxes label 1:8 in 1:9 and 1:7 labels in 1:8 with good results. I'n quite sure that all those 6.5 CREEDs out there that BHW has done aren't just shooting the lightweights.
Grreg
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sil9mm
Junior Member
Posts: 22
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Post by sil9mm on Jan 2, 2018 7:19:06 GMT -8
Thanks Greg. Your very helpful.
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Post by GLSHOOTER on Jan 21, 2018 19:02:59 GMT -8
I ordered mine as 1-8 because it takes a lot of velocity to make up for the difference of an inch in twist. Twist rate and velocity while technically linked have virtually no discernable effect on speed. If it were 10 fps between a 7-8 or 8-9 I would be very surprised based on my results over the yeard. It has more effect on bullet jacket behavior at top speeds and of course bullet length. Greg |
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Post by GLSHOOTER on Jan 22, 2018 6:31:37 GMT -8
That's not what I'm saying. I said it takes a whole lot of MV to make up for what an inch of twist gains you in regard to stability. I'm saying, go plug numbers for a stability calculator for a 140gn ELD-M, for instance, at 2750fps from a 1-8 twist and see what your Sg is. Now run that same calculation with a 1-9, all else being equal, and tell me how much faster you need to push that bullet to achieve the same Sg. Now, can you realistically achieve that MV and why would you push that hard when you could have just bought a more adequate twist? A 1-9 might get it done just like all your bullets you shot in too slow of a twist but your BC likely will suffer. That said, I have shot M118LR past 1300m in our older 1-11.25" twist guns but testing in the past couple years shows the same bullet does better in twists as fast as 1-8. You can't shoot a 175gn in any 308 Win with 1-11.25" twist (regardless of length) fast enough to achieve the same Sg. You are correct on that one. It takes a lot of speed to eCommerce a marginal twist rate. Some guys go a bit overboard on fast twist rates but the rule of thumb is get one that is one twist faster that needed if you antipathetic playing longer. I've never dealt with the twist calculators as I always get that one faster twist and m pretty familiar with what it takes to get it done. I also don't believe the print on the side of the box when using these BHW barrels. AS I mentioned they shot equivalent to one twist faster than they really are from my experience. Greg |
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Post by GLSHOOTER on Jan 22, 2018 12:54:12 GMT -8
Thast's pretty much what my experience has told me as to twist rates. I tend to stay away from the really heavy for caliber stuff but I like to be able to shoot it if the mod strikes.
Greg
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Post by onthedivide on Jan 23, 2018 10:27:00 GMT -8
How would this apply to the 5.56? What would be the optimal bullet weight for twist rate given the capability of the cartridge?
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Post by GLSHOOTER on Jan 23, 2018 12:10:18 GMT -8
How would this apply to the 5.56? What would be the optimal bullet weight for twist rate given the capability of the cartridge? 69 and under a 1:9, up to 80's 1:7 I'm shooting 77's in an 8 with good results. 1:8 though the longer ones prefer the 7. Anything over 80 would be ideally around a 6.5 though some claim the 90 will do a 6.7 or so. That is marginal and if you want the 100's that Federal was trying to do you'd better be at a flat 6 but ralistically that is way to much for a 223. The 90 is on the ragged edge and most long range 223 guys that I shoot with at 1000 have gone back to the 80's. The light stuff down to 40 usually responds well to slower twists and were shot in 12's years ago.The 10 showed up and it was ideal for the 55's or so. You most certainly can shoot the lights in a fast twist but bullet construction may be limiting in some situations because of the speed.The over rotation once you step up to even faster velocities in the non-556 chamberings that use 223 bullets can be a real issue along with blowing up bullets in-flight. Greg |
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Post by toolsofthetrade on Feb 22, 2023 15:19:51 GMT -8
looking to build a 6mm CM, was wondering which twist would be recommended for bullets that would be suitable for both predators and medium sized game (whitetails)
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Post by GLSHOOTER on Feb 22, 2023 15:22:17 GMT -8
9 or ten would do it.
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