Go Back   Alberta Outdoorsmen Forum > Main Category > Guns & Ammo Discussion

Reply
 
Thread Tools Display Modes
  #1  
Old 11-10-2017, 01:22 PM
chuck's Avatar
chuck chuck is offline
 
Join Date: May 2007
Posts: 9,920
Default Why do we need slow twist barrels again?

I was shooting 40gr Ballistic Tips in an 8 twist 223 yesterday. Once again, light bullets seemed to do just fine in a quicker twist barrel. Is there a good reason why manufacturers continue to use slow twist barrels in many of their offerings?



__________________
"All rifle mechanisms are not the same when it comes to reliability in the field."
-Bob F.
Reply With Quote
  #2  
Old 11-10-2017, 01:28 PM
Smokinyotes Smokinyotes is offline
 
Join Date: Jan 2013
Location: onoway, Ab
Posts: 3,958
Default

Good question Chuck. Not sure what the purpose of slow twist barrels is. I would like to be able to shoot 80gr bullets in my 22-250. Kind of tough with a 1-14 twist.
Reply With Quote
  #3  
Old 11-10-2017, 01:41 PM
7mmremmag 7mmremmag is offline
 
Join Date: Jan 2010
Location: Lloydminster
Posts: 1,350
Default

Quote:
Originally Posted by Smokinyotes View Post
Good question Chuck. Not sure what the purpose of slow twist barrels is. I would like to be able to shoot 80gr bullets in my 22-250. Kind of tough with a 1-14 twist.
I just purchased a lefty Tikka in 22-250. Kind of disappointing its a 1-14 twist.
Reply With Quote
  #4  
Old 11-10-2017, 01:44 PM
chuck's Avatar
chuck chuck is offline
 
Join Date: May 2007
Posts: 9,920
Default

Quote:
Originally Posted by 7mmremmag View Post
I just purchased a lefty Tikka in 22-250. Kind of disappointing its a 1-14 twist.
Especially when they are producing 8 twist .224 barrels.
__________________
"All rifle mechanisms are not the same when it comes to reliability in the field."
-Bob F.
Reply With Quote
  #5  
Old 11-10-2017, 02:02 PM
wwbirds's Avatar
wwbirds wwbirds is offline
 
Join Date: May 2009
Location: near Calgary
Posts: 5,704
Default I always thought

it was so the fast twist did not destroy the fragile "varmint" bullets leaving the barrel. Every 22-250 I have owned has been 1-12 or 1-14. come to think of it I believe my BRNO 223 is 1-12 as well
__________________
Count down is on for 2017 hunting season!!!!
Reply With Quote
  #6  
Old 11-10-2017, 02:20 PM
260 Rem 260 Rem is offline
 
Join Date: Nov 2009
Location: East Central Alberta
Posts: 6,673
Default

When buying a barrel, I prefer to get the slowest twist that will stabilize the bullet I plan to shoot.
__________________
Old Guys Rule
Reply With Quote
  #7  
Old 11-10-2017, 07:20 PM
gtr gtr is offline
 
Join Date: Nov 2013
Location: Manitoba
Posts: 1,247
Default

Quote:
Originally Posted by 7mmremmag View Post
I just purchased a lefty Tikka in 22-250. Kind of disappointing its a 1-14 twist.
Usually a few things when people purchase a tikka that can be a concern.
__________________
Only accurate people are interesting.
Reply With Quote
  #8  
Old 11-10-2017, 07:26 PM
Smokinyotes Smokinyotes is offline
 
Join Date: Jan 2013
Location: onoway, Ab
Posts: 3,958
Default

Quote:
Originally Posted by gtr View Post
Usually a few things when people purchase a tikka that can be a concern.
Care to elaborate?
Reply With Quote
  #9  
Old 11-10-2017, 07:33 PM
chuck's Avatar
chuck chuck is offline
 
Join Date: May 2007
Posts: 9,920
Default

Quote:
Originally Posted by Smokinyotes View Post
Care to elaborate?
He can’t and won’t.
__________________
"All rifle mechanisms are not the same when it comes to reliability in the field."
-Bob F.
Reply With Quote
  #10  
Old 11-11-2017, 04:07 PM
260 Rem 260 Rem is offline
 
Join Date: Nov 2009
Location: East Central Alberta
Posts: 6,673
Default

Here's a three shot group (100M) from a hunting rifle shot about noon today. As much as I would like to attribute the result to "appropriate twist", I suspect it could be related to blind luck or perhaps a friendly gust of wind


Sent from my iPad using Tapatalk
__________________
Old Guys Rule
Reply With Quote
  #11  
Old 11-11-2017, 05:41 PM
chuck's Avatar
chuck chuck is offline
 
Join Date: May 2007
Posts: 9,920
Default

Quote:
Originally Posted by 260 Rem View Post
Here's a three shot group (100M) from a hunting rifle shot about noon today. As much as I would like to attribute the result to "appropriate twist", I suspect it could be related to blind luck or perhaps a friendly gust of wind


Sent from my iPad using Tapatalk
This is not a thread about attribution of group size to twist rate. This is a thread about why in the wide world of sports would i hamstring myself with a ridiculously slow twist rate when I don’t have to. I’m quite confident that you can shoot 1/2” groups with 40 gr bullets in a 1-14 twist 223. I’m also quite confident that you can’t shoot 1/2” groups with 75gr bullets 1-14 twisted 223.
__________________
"All rifle mechanisms are not the same when it comes to reliability in the field."
-Bob F.
Reply With Quote
  #12  
Old 11-11-2017, 06:15 PM
dogslayer403's Avatar
dogslayer403 dogslayer403 is online now
 
Join Date: Jul 2010
Location: Rocky Mt. House
Posts: 1,714
Default

I had an interesting experience today with the same 22-250 mentioned earlier was testing some 62g varmagedon i wanted to see if i could get a load with cfe223. 2 loads on the upper end of my test had bullet failures out of 10 shots with the 2 groups i had 4 bullets come apart i thought i seen dirt fly when shooting about 40yds in front of me. Sure enough when i walked up to check groups i seen where parts of them hit the ground and missing 4 holes on paper for those groups.
Now im not saying this was my fast twist as it could just be a bad batch of bullets or their construction but none the less interesting i forgot my chronograph but estimated around 3400-3500 on the ones that failed. Disappointing as the groups were getting better the faster i pushed em

Im gonna test them in my 1/9 223 as well see if i have better luck
Reply With Quote
  #13  
Old 11-11-2017, 07:56 PM
260 Rem 260 Rem is offline
 
Join Date: Nov 2009
Location: East Central Alberta
Posts: 6,673
Default

Sorry Chuck, I must have missed the point about the relationship between twist rate and group size because of the pic in your OP. And you must have missed my point that twisting a bullet with the least rotation required to stabilize it, might work even better? So, here is a pic of some consecutive groups I shot with a hunting contour barrel I used last year ... with the least twist required to stabilize the bullet ... which I think provides some support for the practice of not over rotating bullets. I don't think it is credible to suggest that a single/fast twist rate is a "fits all" solution.
__________________
Old Guys Rule
Reply With Quote
  #14  
Old 11-11-2017, 08:29 PM
chuck's Avatar
chuck chuck is offline
 
Join Date: May 2007
Posts: 9,920
Default

Quote:
Originally Posted by 260 Rem View Post
Sorry Chuck, I must have missed the point about the relationship between twist rate and group size because of the pic in your OP. And you must have missed my point that twisting a bullet with the least rotation required to stabilize it, might work even better? So, here is a pic of some consecutive groups I shot with a hunting contour barrel I used last year ... with the least twist required to stabilize the bullet ... which I think provides some support for the practice of not over rotating bullets. I don't think it is credible to suggest that a single/fast twist rate is a "fits all" solution.
You have missed the point. By a country mile. Again.
__________________
"All rifle mechanisms are not the same when it comes to reliability in the field."
-Bob F.
Reply With Quote
  #15  
Old 11-11-2017, 08:41 PM
duceman duceman is online now
 
Join Date: Aug 2008
Location: south of calgary
Posts: 1,553
Default

here's the follow up question:
what the hell is the draw toward dink bullets with high powder capacity cases; for example 50 gr bullet in a 40 gr powder capacity 22-250.
__________________
220swifty

1. People who list their arguments in bullets points or numerical order generally come off as condescending pecker heads.

2. #1 is true.
Reply With Quote
  #16  
Old 11-11-2017, 10:55 PM
dogslayer403's Avatar
dogslayer403 dogslayer403 is online now
 
Join Date: Jul 2010
Location: Rocky Mt. House
Posts: 1,714
Default

Quote:
Originally Posted by duceman View Post
here's the follow up question:
what the hell is the draw toward dink bullets with high powder capacity cases; for example 50 gr bullet in a 40 gr powder capacity 22-250.
Why not? Perfect for coyote calling very broad PBR with the flat trajectory of a fast light bullet. Heavy high bc bullets in .224 arnt gonna shine till they get way out there and seldom do I need that yote hunting plus hard on fur with a 70-80g bullet. Kinda the staple of varmint hunting is frangible fast light bullets and flat trajectory is it not? Target shooting is another story I suppose

Last edited by dogslayer403; 11-11-2017 at 11:07 PM.
Reply With Quote
  #17  
Old 11-12-2017, 07:07 AM
duceman duceman is online now
 
Join Date: Aug 2008
Location: south of calgary
Posts: 1,553
Default

i shoot coyotes to 400 pretty routinely with a 222 running a 50 gr bullet at 3100. if your not shooting long, why burn twice the powder for another 6-700 fps with the same bullet? coyote tips over regardless....
__________________
220swifty

1. People who list their arguments in bullets points or numerical order generally come off as condescending pecker heads.

2. #1 is true.
Reply With Quote
  #18  
Old 11-16-2017, 04:30 PM
lclund1946 lclund1946 is offline
 
Join Date: Apr 2010
Location: Rimbey, AB
Posts: 511
Default

Quote:
Originally Posted by duceman View Post
here's the follow up question:
what the hell is the draw toward dink bullets with high powder capacity cases; for example 50 gr bullet in a 40 gr powder capacity 22-250.
The vast majority of people have no idea about ballistics or why your 222 is much more fur friendly at close range yet gets the job done at 400 yards. I have talked to many people who rave about their pet 22-250 coyote load only to qualify by saying "I can't shoot more than 2 or three rounds without blowing primers though". Hornady show a max of 3800 fps with the 50 V-Max and my Ballistics program shows 3680 for a Factory 55 HP bullet yet many of these same people believe that pushing these bullets 200 fps faster is Ok as they shoot so flat.

However if you go to a 39/40 grain bullet in a 20 caliber at 3650, which can be done with 22.2-22.4 grains of powder in a properly designed cartridge with an 11"twist barrel, the PBR is very close and the 20 will do better in the wind. The problem with going to a 20 caliber is that no manufacturer makes anything but the standard 12" twist barrel, which do not work very well with the 39/40 grain bullets, unless they are pushed to over 2700 fps. Most 20 cartridge designs require pressures of 63,000 PSI to get there accurately and then some think it OK to find an accuracy node at 3900 fps.

The main reason that manufacturers have not been in a hurry to go to faster twist barrels is marketing but Cartridges like the 20 Var-Targ and 20 Tactical do not lend themselves to running 39/40 grain bullets, with in Saami standard pressures as they are either too small or too large, in capacity, and they will not fit in standard magazines without running well off the lands.

I realized this early on and decided to design my own 20 caliber that had none of these problems. I also realized that a 40 V-Max would stabilize nicely at 3470 fps and run the same trajectory as a 22-250 with a Factory 55 HP
bullet which the Leupold VH Reticle was calibrated. I was elated to find that this low pressure load was better in the wind as well. The 22-250 trajectory is in yellow and is virtually covered by the 40 V-Max trajectory to 500 yards.
[IMG][/IMG]

When IMR 8208 I was able to get the 39/40 grain bullets to 3650 fps which does make the 22-250 look a bit anemic, with 50-55 grain bullets, even when pushed to the max. Going to a 9" twist with the 55 Berger and Varget really make the 22-250, or any of the other 20 Calibers with 12" twist look rather sick. Duceman, you will be really pleased when you get to try this load out on a few coyotes, when you get the time, and I look forward to a complete review.
[IMG][/IMG]

The 11" and 9" twist barrels have no problem stabilizing, or shooting accurately, good loads in 32 (3850 - 4000 fps) and 39/40 ( 3500 -3650 fps) grain loads in all rifles.
[IMG][/IMG]
[IMG][/IMG]
[IMG][/IMG]

Last edited by lclund1946; 11-16-2017 at 04:37 PM.
Reply With Quote
  #19  
Old 11-13-2017, 10:37 PM
PartTimeHunter PartTimeHunter is offline
 
Join Date: Aug 2013
Posts: 850
Default

Quote:
Originally Posted by chuck View Post
I was shooting 40gr Ballistic Tips in an 8 twist 223 yesterday. Once again, light bullets seemed to do just fine in a quicker twist barrel. Is there a good reason why manufacturers continue to use slow twist barrels in many of their offerings?



I think the slower twists are to conform with the manufacturers offerings of bullet weights in factory ammo and don't take handloaders into account. Why they don't consider other choices I can't answer. My understanding is that you can over twist for lighter bullets. In my 20 Extreme with an 8 twist barrel I can shoot the 55 grain Bergers lights out, 40 grain works good too. I have not been able to work up a load with 32 grain bullets for that rifle and didn't even try the 26. I also have a 10 twist in 20 Extreme that works fantastic with 40 grain but can't stabilize the 55's. I have heard and read of bullets "misting" on the way down range. There is a guy on the other site for nutz that posted a formula for maximum bullet rotation. He experimented with some wildcats and used this to find the right twist for the chosen bullet.

Last edited by PartTimeHunter; 11-13-2017 at 10:47 PM.
Reply With Quote
  #20  
Old 11-13-2017, 11:45 PM
260 Rem 260 Rem is offline
 
Join Date: Nov 2009
Location: East Central Alberta
Posts: 6,673
Default

The “greenhill formula” (and its fine tuned offspring) using the bullet diameter, length, specific gravity, and velocity ... provides the basis for calculating the optimum rotation required for stabilization. Although rotating a bullet faster than the “optimum” has no theoretical deleterious effect itself, bullet construction that is not “perfect” ... say in weight distribution, uniform jacket thickness, and a host of other factors... will amplify the imperfection and may result in poor performance. Consequently, the best advice is to choose bullet/characteristics that fit in the range of optimum stability provided by a given twist.
So, to address the issue posed in the OP, it is evident that maqnufacturers make slow twist barrels for specific (shorter) bullets, and faster twists for their longer cousins. Yes, we still need slow twist barrels because over rotating a bullet with deficiencies, is unlikely to give the best results.
It is quite possible that a well constructed bullet may shoot “decent”, which does not rise to the standard of shooting “well”.
If manufactures thought their barrels would shoot every length of bullet well with a fast twist ie: 1:7 ...they would just make them all that way and not bother with extra retooling costs.
__________________
Old Guys Rule
Reply With Quote
  #21  
Old 11-14-2017, 07:17 AM
elkhunter11 elkhunter11 is online now
 
Join Date: Dec 2008
Location: Camrose
Posts: 29,517
Default

So shooting the same load in two rifles with different twist rates produced a difference in velocity of only 10fps? Has anyone actually measured the pressure produced in both barrels with the same load? If the fast twist barrel is producing more pressure , then you would need to change the load to produce equal pressure in both barrels to determine the true effect of twist rate on velocity. And even if the same pressure only produces 20fps more with a slow twist barrel, why not take advantage of that 20fps if the accuracy is the same? If I am only going to shoot a 55gr bullet , why use a twist that is optimum for 80gr, and give up 20fps that I can have for nothing?
I have owned six 7mmstw rifles, four with a 1 in 10" twist, and two with a 1 in 9" twist. All shot 140-150gr bullets well, but the 1 in 9" rifles did not shoot the 140gr bullets as well as they shot 150 gr bullets. The 1 in 10" rifles preferred the 140gr bullets. So is this simply coincidence, or is the twist rate a factor? And this is with only a 1" difference in the rate of twist.
__________________
Only accurate guns are interesting.

Last edited by elkhunter11; 11-14-2017 at 07:25 AM.
Reply With Quote
  #22  
Old 11-14-2017, 08:42 AM
densa44 densa44 is offline
Moderator
 
Join Date: Jul 2010
Location: East of Stettler
Posts: 5,876
Default Fascinating post

The rub is of course, no matter how hard you try you can't keep all the variables constant while you manipulate rate of twist.

Some of the posts are very scientific and I really appreciate that. The Litz test (I think that is what it was) and Elk's last post may be showing that the small difference in MV moves the point of impact due to harmonics not bullet stabilization.

I calculated the rpm of bullets exiting the barrel once and they were extremely high and it is hard to believe that a higher rpm makes them more stable.

Maybe the different twists rates are just a marketing tool? As others have said, its how they shoot that counts.

Good stuff.
__________________
"The well meaning have done more damage than all the criminals in the world" Great grand father "Never impute planning where incompetence will predict the phenomenon equally well" Father
Reply With Quote
  #23  
Old 11-14-2017, 08:46 AM
fish_e_o's Avatar
fish_e_o fish_e_o is offline
 
Join Date: Jan 2010
Location: rollyview
Posts: 7,510
Default

Quote:
Originally Posted by densa44 View Post
I calculated the rpm of bullets exiting the barrel once and they were extremely high and it is hard to believe that a higher rpm makes them more stable.

Maybe the different twists rates are just a marketing tool? As others have said, its how they shoot that counts.
you can see the results of an unstabilized bullet in the B.C.
__________________
Savage barrel nuts
Reply With Quote
  #24  
Old 11-15-2017, 10:38 PM
Salavee Salavee is offline
 
Join Date: Sep 2008
Location: Parkland County, AB
Posts: 2,038
Default

Generally speaking, the longer the bullet the faster the twist required to stabilize it properly .. not necessarily the reverse.
If you plan to use heavy for caliber bullets primarily, get a faster twist.
Nominal factory twist rates are built to suit the bullets most commonly used in them.
For eg , a .308 Win does not handle large for caliber bullets well and is usually twisted a 1-12 or 1-14. A 30-06 does handle the larger bullets well and has a normal twist rate at 1-10.
__________________
When applied by competent people with the right intent, common sense goes a long way.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 07:15 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.