GlockTalk.com
Home Forums Classifieds Blogs Today's Posts Search Social Groups



  
SIGN-UP
Notices

Glock Talk
Welcome To The Glock Talk Forums.

 
  
Reply
 
Thread Tools Display Modes
Old 12-08-2012, 10:10   #1
greenlion
Senior Member
 
greenlion's Avatar
 
Join Date: Jul 2009
Location: North Carolina
Posts: 929
Handgun Barrel Twist-Rate Article

For those of you who just picked up (or will) the new issue of Handguns magazine, there is an interesting article about bullet stability after penetrating barriers, using different barrel twist rates. (Twist and Shout: by Dick Metcalf) I won't spoil the article for those who have not read it, but if you have already, you will probably be wondering what the twist rates are for GLOCK barrels.

Here ya go..

For all 9mm, 10mm, .357, and .40 caliber pistol lines, the twist rate is - One in 9.84 in.

For the .45ACP and .45GAP lines, the twist is - One in 15.74 in.
greenlion is offline   Reply With Quote
Old 12-08-2012, 14:26   #2
SJ 40
Senior Member
 
SJ 40's Avatar
 
Join Date: Jan 2011
Location: Vermont
Posts: 6,969
I'll be interested to read it. I know that the Wilson barrel that I have for a G 22 that is 1/16" at 25 yards is not greatly more or less accurate than a factory barrel. SJ 40
SJ 40 is offline   Reply With Quote
Old 12-09-2012, 01:03   #3
.38 super
Observer
 
.38 super's Avatar
 
Join Date: Aug 2010
Location: Florida
Posts: 1,649
Pistol bullets does not need much stabilization compared to rifle bullets where the center of gravity is close to the tail of the bullet rather than the front part... On the other hand the faster the bullets spins, the better penetration is...

I will get the magazine, because it is interesting to read the article, but with all my respect to Mr Metcalf, some 3-4 years ago he wrote that on S&W, M&P when you pull the trigger it additionally loads the striker before release it, which is incorrect, M&P's striker is fully loaded by the cycle of the gun... I did send him an a nice e-mail asking about it, stating a video by AGA where you can clearly see that striker does not go back when the trigger is pulled but did not have any respond... Not like I was expecting one... It wasn't very important anyway...
__________________
Μολων λαβε !
____________________________
Florida Glockers Club #1964
Калашников Клуб №1000
.38 super is offline   Reply With Quote
Old 12-09-2012, 07:29   #4
greenlion
Senior Member
 
greenlion's Avatar
 
Join Date: Jul 2009
Location: North Carolina
Posts: 929
Quote:
Originally Posted by .38 super View Post
Pistol bullets does not need much stabilization compared to rifle bullets where the center of gravity is close to the tail of the bullet rather than the front part... On the other hand the faster the bullets spins, the better penetration is...
That is the interesting bit in the article though. It shows what happens to bullets spinning with a faster twist rate AFTER they penetrate the barrier. He also tells how slow motion cameras have revealed bullets doing much more than they should be doing during regular flight, when the twist is too slow.

He says that, based on new evidence, many manufacturers in the industry are changing their minds about what you stated in your post, and going with a faster twist rate for pistol bullets.
greenlion is offline   Reply With Quote
Old 12-09-2012, 10:46   #5
SJ 40
Senior Member
 
SJ 40's Avatar
 
Join Date: Jan 2011
Location: Vermont
Posts: 6,969
It will be interesting to see if the Greenhill formula gets redone or replaced at least when it comes to handguns. SJ 40
SJ 40 is offline   Reply With Quote
Old 12-09-2012, 14:54   #6
.38 super
Observer
 
.38 super's Avatar
 
Join Date: Aug 2010
Location: Florida
Posts: 1,649
Quote:
Originally Posted by greenlion View Post
That is the interesting bit in the article though. It shows what happens to bullets spinning with a faster twist rate AFTER they penetrate the barrier. He also tells how slow motion cameras have revealed bullets doing much more than they should be doing during regular flight, when the twist is too slow.

He says that, based on new evidence, many manufacturers in the industry are changing their minds about what you stated in your post, and going with a faster twist rate for pistol bullets.
This will be interesting article and I'll pick up the magazine tonight... Actually this is well known fact in rifle bullets - for example, 7.62 AK round comes out of 1:10 twist rate barrel, where 5.56 AR round comes out of 1:7 barrel twist ( very generally speaking...) Even the AK round is heavier and brakes bricks and such barrier material, it will not compare at any way to the AR round that drills trough steel plates way easier... One of the reasons is - it is more stabilized... Of course this is very raw example - AK round is intermediate cartridge and 5.56 is a rifle cartridge but you got the idea...
a simple, hot loaded FMJ 9x19 will easily penetrate 16" FBI protocol, gelatin block, even out of 4" barrel, but I don't understand who will need such round unless we are talking some special purposes guns and ammo...
__________________
Μολων λαβε !
____________________________
Florida Glockers Club #1964
Калашников Клуб №1000
.38 super is offline   Reply With Quote
Old 12-09-2012, 18:54   #7
jeremy1
Senior Member
 
Join Date: Jan 2006
Location: Armed In Alberta
Posts: 1,221
I didn't read the article, but have read PO Ackley's books, and this is nothing new. he experimented with twist rates extensively, and claimed that the RPM is more important that muzzle energy when penetrating. In one test he shot 1/2 " armour plate with a 30.06, 270, and 220 swift. The Swift was the only round to penetrate even though the muzzle energy was considerably less.

The theory is sound, but the question is what do you need to penetrate with a hand gun?
__________________
G17 gen 1, G19, G20 OD, G22 gen 4, G37 and lots of other Non Glocks
jeremy1 is offline   Reply With Quote
Old 12-09-2012, 19:31   #8
.38 super
Observer
 
.38 super's Avatar
 
Join Date: Aug 2010
Location: Florida
Posts: 1,649
Which one is about twist rate experiments, if you can point it to me ? I am curious to look at it, TIA.
__________________
Μολων λαβε !
____________________________
Florida Glockers Club #1964
Калашников Клуб №1000
.38 super is offline   Reply With Quote
Old 12-09-2012, 21:30   #9
jeremy1
Senior Member
 
Join Date: Jan 2006
Location: Armed In Alberta
Posts: 1,221
Quote:
Originally Posted by .38 super View Post
Which one is about twist rate experiments, if you can point it to me ? I am curious to look at it, TIA.
I went looking and it is in Handbook for Shooters and Relaoders Volume 1 Page 81. This is in the killing power and there are pics of the armour plate that was shot at with the 30.06, 270, and 220 swift.

I did read another article from an old reloading magazine a friend had, but I dont have access to it.

His books are excellent and a must read for reloaders.
__________________
G17 gen 1, G19, G20 OD, G22 gen 4, G37 and lots of other Non Glocks
jeremy1 is offline   Reply With Quote
Old 12-09-2012, 22:50   #10
.38 super
Observer
 
.38 super's Avatar
 
Join Date: Aug 2010
Location: Florida
Posts: 1,649
Quote:
Originally Posted by jeremy1 View Post
I went looking and it is in Handbook for Shooters and Relaoders Volume 1 Page 81. This is in the killing power and there are pics of the armor plate that was shot at with the 30.06, 270, and 220 swift.

I did read another article from an old reloading magazine a friend had, but I dont have access to it.

His books are excellent and a must read for reloaders.
I'll look it up, thank you. I found some of the books in Amazon, one of them was like $170+, I'll go check the volume you mention, hopefully it isn't terribly expensive...
__________________
Μολων λαβε !
____________________________
Florida Glockers Club #1964
Калашников Клуб №1000
.38 super is offline   Reply With Quote
Old 12-09-2012, 23:35   #11
rimshaker
Senior Member
 
Join Date: Feb 2012
Posts: 153
Twist rates and bullet stability are also very important when it comes to using silencers. Last thing you want is the bullet touching anything.

Glock and HK barrels use the same 1:9.84" rifling and Sig uses 1:10". Most aftermarket barrels use the slower 1:16" rifling. So basically stick with OEM factory barrels.
rimshaker is offline   Reply With Quote
Old 12-10-2012, 13:41   #12
jeremy1
Senior Member
 
Join Date: Jan 2006
Location: Armed In Alberta
Posts: 1,221
Quote:
Originally Posted by .38 super View Post
I'll look it up, thank you. I found some of the books in Amazon, one of them was like $170+, I'll go check the volume you mention, hopefully it isn't terribly expensive...
They are hard to find. I have to return them to the guy who lent them to me. He is asking. I have been looking for a set, but no luck.
__________________
G17 gen 1, G19, G20 OD, G22 gen 4, G37 and lots of other Non Glocks
jeremy1 is offline   Reply With Quote

 
  
Reply


Tags
barrel, barrier, handguns, rifling, twist
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 -6. The time now is 05:32.




Homepage
FAQ
Forums
Calendar
Advertise
Gallery
GT Wiki
GT Blogs
Social Groups
Classifieds


Users Currently Online: 944
209 Members
735 Guests

Most users ever online: 2,244
Nov 11, 2013 at 16:42