Author Topic: I thought a 1-7 twist was more stable for heavy bullets?  (Read 3226 times)

0 Members and 1 Guest are viewing this topic.

Offline armoredman

  • Administrator
  • Hero Member
  • *****
  • Posts: 19821
I thought a 1-7 twist was more stable for heavy bullets?
« on: October 24, 2016, 01:24:58 AM »
Maybe I'm too close?



Yes, I got the BREN out with some handloads today from that mystery box o' goodies I got the other day. ;) Some of these really surprised me. The rifle was, of course, as always, absolutely flawless. All are 5 shot groups, fired seated, front rested, 50 yards, because as much as I like this red dot - it totally obscures the 1" black box at 50 yards, and is kinda hard to manage at 100 yards until I print up some bigger bullseye targets. I know, cheap excuse, but any port in a storm. ;)

My stand by - these bullets are usually available locally. Not cheap, but local.



A generic bullet did surprisingly VERY well!





Not  a fluke at all...



And I was told light bullets wouldn't work at all with a fast twist...



Now it's time to break open that box of 53 grainers and see what they can do. :D

Offline FireMoose

  • Sr. Member
  • ****
  • Posts: 557
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #1 on: October 24, 2016, 02:18:07 AM »
Nice shooting and loads.


Offline Joe L

  • Hero Member
  • *****
  • Posts: 7197
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #2 on: October 24, 2016, 04:01:47 AM »
There is something right going on here.   :) :)
Joe
CZ-75B 9mm and Kadet, 97B"E", two P-09's, P-07, P-10C, P-10F, P-10S, MTR

Offline M1A4ME

  • Hero Member
  • *****
  • Posts: 7453
  • I've shot the rest, I now own the best - CZ
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #3 on: October 24, 2016, 07:00:21 AM »
I've read that, too - light bullets won't shoot very well in a fast twist.  Not true for some bullets.

At one time (30 plus years ago) I know Sierra and Hornady made thin jacketed 40 and 45 grain varmint bullets.  The idea was to use them in .222 and .223 Remington cartridges to give you similar expansion (at the lower velocities of those cartridges) to what you get from the standard bullets in .22-250's and .220 Swifts.

In those days most .222's had a twist of around 1 turn in 14" and .223's had a twist of 1 turn in 12".  My M700 Rem. varmint special has a twist of 1 turn in 12" (bought it in 1980).

I used those thin jacketed 45 grain bullets for my varmint hunting.  I think Hornady called theirs "SX" bullets and Sierra called theirs "Blitz" bullets.  At that time the "heavy" bullet for a .223 had been the 55 grain bullet and the 62 or 65 grain bullets were beginning to get popular for people wanting to shoot deer with those calibers (where it was legal).  That forced the gun manufacturers to go to a faster twist of 1 turn in 9" for their barrels.  When I bought my Mini 14 in 1982 or 83 it had a 1 turn in 9" barrel on it.

The reloading manuals (at least one, but I don't remember whether it was the Hornady or the Sierra, specifically stated that their thin jacketed bullets should not be used in a 1 turn in 9" barrel as the bullet jacket was not designed for the stress of the higher rpm spin given the bullet by the faster twist rate.  I decided to shoot some in my Mini14.  I used the same ammo I ground hog hunted with in my M700.  You could visually "track" the bullet downrange by a swirling vapor trail off the bullet.  Pretty wild looking.  And when you tried to shoot a 10 shot group at 100 yds. you might get 8 bullet holes.  Sometimes you could see the vapor trail disappear between the gun and the target.  Now the shooter didn't notice the vapor trail, but the folks you were shooting with could see it plainly.  We assumed it was very small particles coming off the bullet.  You wouldn't see that vapor trail when the same ammo was fired in the 1 turn in 12" M700.

If those bullets couldn't withstand a 1 turn in 9" barrel I'll bet none of them would make it to the target with a 1 turn in 7" barrel.

Try a different load with the 75's.  Some people report good results with IMR4895 or TAC.  Different rifles are, different.
I just keep wasting time and money on other brands trying to find/make one shoot like my P07 and P09.  What is wrong with me?

Offline jameslovesjammie

  • Hero Member
  • *****
  • Posts: 4608
  • The Last Best Place
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #4 on: October 24, 2016, 11:33:54 PM »
I've posted this picture before.  It's a 100 yard group of a 40 grain Nosler Ballistic Tip in my 1/8 twist AR.



It is the best group that I have shot...ever...in any gun.  I have to keep in mind, however, that this is a sample of 1.  This load doesn't always print this well.  In fact it usually hovers right under the 3/4" mark.  For some reason, the stars just aligned that day, tolerances stacked, and things came together.

A better bullet is the 69 grain Sierra Matchking.  It consistently prints between .4-.5" at 100.  All the time, all day long.



Sometimes we need to keep in mind that while single fantastic groups can show up during development, a REPEATABLE load will mean more over the long run.

skin

  • Guest
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #5 on: October 25, 2016, 12:18:44 AM »
 I have a custom 22-250 AI with a 1-8 twist, mainly for the 69 gr and up. For s and g's, I worked up a load for the 40 gr Noslers not hoping for much. Turned out it is one of my most accurate loads. At 4500 fps + it's getting close to the top end for the bullet. I think Nosler said the top was somewhere around 5000 fps. I have read that there is no such thing as over stabilization. I firmly believe in this now.

Offline armoredman

  • Administrator
  • Hero Member
  • *****
  • Posts: 19821
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #6 on: October 25, 2016, 12:30:40 AM »
Sweet steel, that an awesome group, sir!  :o  8) I'd show that thing off until I was old and gray....waitaminnit, I am old and gray...never mind... ;D
To be clear, these are the very old Sierra bullets from the 60s, currently sold at MidwayUSA as the Varminter, usually meant for a 22 Hornet, I guess. I like it. The 50 grain Dogtown JHP bullets also worked far better than I expected, being, really, a generic bullet, "store brand", as it were, even though they say Nosler makes 'em. :) I'm gonna have to get more of these, think they might be good for a lot of things, but with fast, violent expansion, probably not good for SD work.

Offline jameslovesjammie

  • Hero Member
  • *****
  • Posts: 4608
  • The Last Best Place
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #7 on: October 25, 2016, 09:36:55 AM »
...At 4500 fps + it's getting close to the top end for the bullet.

Holy Guacamole!  That's spinning at 405,000+ RPM's!

Offline noylj

  • Full Member
  • ***
  • Posts: 453
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #8 on: October 27, 2016, 12:14:16 AM »
In GENERAL, the longer the bullet, the faster the twist rate needed to stabilize the bullet. However, your barrel is NOT most barrels. Barrels/bullets sometimes seem to defy logic and physics and just do what they want
It seems EVERY time I see a test of .223 rifles, there is always one rifle with a 1:12 twist that does well with some particular 50-65 gn bullet and another rifle with a 1:7 twist that does best with a particular 40 gn bullet. You learn by testing.

Online Wobbly

  • Administrator
  • Hero Member
  • *****
  • Posts: 12481
  • Loves the smell of VihtaVuori in the morning !
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #9 on: October 27, 2016, 05:11:38 AM »
Maybe I'm too close?




Your group is good. So I believe the heavier 60gr bullet has a slower recoil impulse that's simply not lifting the muzzle as much as the lighter bullets which made up the balance of the tested bullets.

If the barrel couldn't handle "heavy" 60gr bullets, then they should be all over the place. They're not. Your group with 60gr is simply lower on the target.

 ;)
In God we trust; On 'Starting Load' we rely.

Offline jwc007

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8649
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #10 on: October 27, 2016, 01:00:08 PM »
Very interesting results!  :)
"Easy is the path to wisdom for those not blinded by ego." - Yoda


For all of those killed by a 9mm: "Get up! You are not dead! You were shot with a useless cartridge!"

Offline armoredman

  • Administrator
  • Hero Member
  • *****
  • Posts: 19821
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #11 on: October 27, 2016, 08:03:56 PM »
Good point, Wobbly, increse the voltage and try again at longer range.

Online Wobbly

  • Administrator
  • Hero Member
  • *****
  • Posts: 12481
  • Loves the smell of VihtaVuori in the morning !
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #12 on: October 27, 2016, 11:23:02 PM »
Good point, Wobbly, increase the voltage and try again....




Precisely, herr doctor !
In God we trust; On 'Starting Load' we rely.

Offline IDescribe

  • Hero Member
  • *****
  • Posts: 4049
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #13 on: October 27, 2016, 11:42:20 PM »
...has a slower recoil impulse that's simply not lifting the muzzle as much as the lighter bullets which made up the balance of the tested bullets.

Exactly.  Could be that.  Could also be barrel whip.


Offline IDescribe

  • Hero Member
  • *****
  • Posts: 4049
Re: I thought a 1-7 twist was more stable for heavy bullets?
« Reply #14 on: October 27, 2016, 11:46:11 PM »