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Very Hot Topic (More than 25 Replies) Best twist for a Lyman 410663? (Read 1327 times)
martini79
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Best twist for a Lyman 410663?
Aug 26th, 2017 at 7:57am
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Hi guys I am building a 40-70 single shot, I have the reamer and dies sorted.The bullet I plan on shooting is a Lyman 410663, possibly other designs of a similar length in the future.

What is the best twist for a bullet of that length, and I am talking about real world experience not stability calculators I have checked through those.
I have read of twists from 1:14 to 1:18.

Twists available to me are 1:13, 1:15, 1:16, 1:17 and 1:18. Shooting will be mostly at 200-300 and less often at 500 yards?

Theoretically 1:18 will work but is a 1:17 or 1:16 a safer bet, that's why I wanted actually experience. I plan on loads of around 1200-1300fps and no more.

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marlinguy
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Re: Best twist for a Lyman 410663?
Reply #1 - Aug 26th, 2017 at 9:08am
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1:15" or 1:16" would both be fine. Probably the 16" for the distances you listed.
  

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jy3855
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Re: Best twist for a Lyman 410663?
Reply #2 - Aug 26th, 2017 at 10:11am
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I went 14" with my CPA 40-72 barrel because I wanted to be sure I'd stabilize  my Snovers (Lyman 410663) out to 1K yards.  Seemed to work well. I rang the 990 plate once I got the sight setting for my MVA tang sight.

I would think 15" and 16" would be fine.
  
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gunlaker
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Re: Best twist for a Lyman 410663?
Reply #3 - Aug 26th, 2017 at 11:17am
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I shoot a .40-65 in Midrange BPTR using a 400gr Money bullet that is a similar weight and length.   1:16 twist works well for me to 600 yards, but I shoot them at just over 1300 fps.   A little bit faster twist isn't going to hurt anything though. 

Chris.
  

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art_ruggiero
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Re: Best twist for a Lyman 410663?
Reply #4 - Aug 26th, 2017 at 1:04pm
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faster twist causes more torque twist   16 twist is fine to 800 yds    art
  
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marlinguy
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Re: Best twist for a Lyman 410663?
Reply #5 - Aug 26th, 2017 at 4:32pm
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art_ruggiero wrote on Aug 26th, 2017 at 1:04pm:
faster twist causes more torque twist   16 twist is fine to 800 yds    art


Sometimes. But the Lyman is a 400 gr. bullet, and it might need a little more twist to stay stable at 800 yds. I've found a lighter 330-350 gr. bullet works excellent at 800 yds. with a 16" twist, but a 400+ gr. bullet begins to tumble at around 700 yds. with a 16" twist.
  

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martini79
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Re: Best twist for a Lyman 410663?
Reply #6 - Aug 26th, 2017 at 6:10pm
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Hi guys, thanks for your great response. It seems consensus is that a 1:16 is probably best.

Not that its necessarily totally correct, but I decided to look at twist rates compared with velocity at a given distance to allow for worse case stability. Highly theoretical I know but potentially the minimum twist to guarantee stability a that distance.

Starting a 1300fps muzzle
200 yards 1:17
500 yards 1:16.5
800 yards 1:16
1 mile       1:15.5

These figures again in theory allow for a high SF, I guess its a case of yes some have done very well with a 1:18 twist, but if you don't want to spend $ on a barrel only for it to be a touch too slow it better to round down to the next fastest twist.

Thus at 500 yards a 1:16 would be the ticket, and there is a good chance it would work fine to a 1000. As I don't think I will ever shoot the mile a 1:15 is probably more than I need.
  
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beltfed
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Re: Best twist for a Lyman 410663?
Reply #7 - Aug 26th, 2017 at 9:44pm
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Martini79,
You wanted examples rather than "theoretical"stability
for the 410663 "Snover" bullet vs twist for the 40-65.
Experience here with 16 twist 40-65s:
I and others have had good results with the Snover
up to midrange -600yds.
Now looking at longer distance: Long range.
The Snover in 16 twist 40-65 shot 'ok" at 800.
"Real Shaky" results at 900, and "Spray and Pray" at 1000yds.
This is only indirectly about Weight of the bullet.
It is particularly about Length of the bullet.
I did not have the option at the time to rebarrel to a faster twist:
SO, I decided to approach long range capablility and along the way better accuracy at all ranges than the Snover was giving me.
So I designed tapered Elliptical ogive Minigroove bullet that is about 50 thou shorter than the Snover. Steve Brooks cut the mold. Actual results: Bullet seated out over 70 gr Swiss 1.5, and clocking 1375fps has shot an 88/100 at 1000yds
and a 99-3X at 800yds at long range match from my custom 16 twist 40-65 HiWall.
Ditto for my encore now into Paper Patch bullet. Same design and length as my E-Mini, and now seated out farther
over 74.5 gr Swiss 1.5I get 1400fps out of it.  See attached pics of a group at 100yds and pic of the bullets/ctges. From right, Snover, E-Mini, E- PP bullets, and EPP loaded 40-65.
The other ctg and bullets on left are for my 40-72 with 12 twist barrel.
Using "reverse" logic, my suggestion to you is if you want to shoot that 410663 to its best, amongst your choices, choose the 15 twist.
beltfed/arnie
  
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beltfed
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Re: Best twist for a Lyman 410663?
Reply #8 - Aug 26th, 2017 at 10:10pm
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Oh, forgot to give the lengths,wts of my bullets :
                  Length             Wt in 9+1WW/lino
Lyman 410663   1.367"         404gr
Elliptical Mini      1.322"         374 gr
DDEllipt PaperP   1.327"         370gr

beltfed/arnie
  
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alex henry two
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Re: Best twist for a Lyman 410663?
Reply #9 - Aug 26th, 2017 at 11:45pm
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Well Ill throw this out there, Twist rate for bullet length?
Dia X 3 then by itself= answer
X twist by .07= answer
Then devide first answer by second =Bullet Length.
As we all know there are other factors involved
If you want to shoot from zero to 1000yds try it yes you can get longer bullets to do well to certain distances then fall in a heap. Just my Two cents worth. Vic



  
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martini79
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Re: Best twist for a Lyman 410663?
Reply #10 - Aug 27th, 2017 at 1:53am
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Thanks for the replies keep the coming.

I suspect that the answer to this question could change within reason depending on range. That for strict 200 yard shooting 1:18 may be the go, but at a mile 1:13 could be the best twist. 1:15 or 1:16 looks like the best all rounder.
  
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bruce moulds
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Re: Best twist for a Lyman 410663?
Reply #11 - Aug 27th, 2017 at 2:52am
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vic,
not sure if i did it right, but i get a length of 1.1" for my 13" twist 40 cal.
it actually handles a 1.5" long bullet in all conditions i have shot in to 1000 yds very well.
using the stability factor on jbm it should easily handle a 1.550" bullet.
generally speaaking a stability factor of 1.8 to 2.00 will handle 1000 yds reliably if the nose shape is suitable.
keep safe,
bruce.
  

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martini79
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Re: Best twist for a Lyman 410663?
Reply #12 - Aug 27th, 2017 at 4:05am
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Hi the concept of the SF matching distance is directly related to twist.

Is a 1.5-1.6 optimal for 200 yard shooting?
  
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alex henry two
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Re: Best twist for a Lyman 410663?
Reply #13 - Aug 27th, 2017 at 4:43am
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Hi Bruce, I get 1.638" by my cal. Used groove dia of .407x3=1.221x1.221=1.490841"
13twist x .07= .91
1.490841 devide by .91= 1.638"  Hopes this helps. Vic
  
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bruce moulds
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Re: Best twist for a Lyman 410663?
Reply #14 - Aug 27th, 2017 at 5:33am
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thanks vic.
i would not even try a bullet that long in that rifle at long range.
went from 1.55 back to 1.50 for reasons mentioned previously.
keep safe,
bruce.
  

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