The Firing Line Forums

Go Back   The Firing Line Forums > The Hide > The Art of the Rifle: Bolt, Lever, and Pump Action

Reply
 
Thread Tools
Old December 24, 2012, 02:16 PM   #1
shredder4286
Senior Member
 
Join Date: May 13, 2010
Location: NE Washington
Posts: 361
Results: Shooting 180 grain bullets in a 1:12" 308 Win barrel

I did a good bit of searching online a few months ago, and found no evidence that a barrel with a 1:12" twist would stabilize a 180 grain bullet in a 308 winchester. I finally bought some Sierra SBT 180's and tried them out. That group was shot at 300 yards. Just thought I'd put it out there for any others that were curious about the matter. Merry Christmas!
Attached Images
File Type: jpg 180gn.jpg (171.5 KB, 183 views)

Last edited by shredder4286; December 24, 2012 at 10:29 PM.
shredder4286 is offline  
Old December 24, 2012, 06:33 PM   #2
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,052
Sierra's 180-gr. match bullets have been shooting from .308 Win. ammo in match grade M14NM's, M1's, and various match grade bolt guns with 1:12 twist barrels into 1/3 MOA at 200 yards, 1/2 MOA at 300, 2/3 MOA at 600 and 3/4 MOA at 1000 yard since the 1960's. They were a favorite of the US Army and USMC Rifle teams back then.

Sierra Bullets' has shot theirs into 1/4 MOA at 200 yards with great repeatability; sometimes even smaller groups close to 1/8 MOA.

I've shot Sierra's first 180-gr. HPMK from 30 caliber magnums with a 1:12 twist barrel into near 1/2 MOA at 1000 yards.

Many matches were won in the 1960's and 1970's with Sierra's 190's from 1:12 twist barrels in 7.62 NATO Garands; even some at the Nationals only a few years ago.

http://riflemansjournal.blogspot.com...-match_04.html
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; December 24, 2012 at 06:42 PM.
Bart B. is online now  
Old December 24, 2012, 07:15 PM   #3
tAKticool
Senior Member
 
Join Date: November 16, 2010
Posts: 418
I have a new Remington 700 AAC-SD .308 with 1:10 rifling and I was under the impression I wanted to be shooting 180 grain ammo so I'd been looking for that, it's harder to find in my area but available (Not as plentiful as lesser grains but)... anyway someone messaged me saying not to 'punish myself' shooting 180 gr, I would be fine with 147-etc. grain ammo... is that true, 180 gr hurts or something?

And anyone else out there with a 1:10 twist what do you like to shoot?

tyry.
tAKticool is offline  
Old December 24, 2012, 10:33 PM   #4
shredder4286
Senior Member
 
Join Date: May 13, 2010
Location: NE Washington
Posts: 361
Quote:
Sierra's 180-gr. match bullets have been shooting from .308 Win. ammo in match grade M14NM's, M1's, and various match grade bolt guns with 1:12 twist barrels into 1/3 MOA at 200 yards, 1/2 MOA at 300, 2/3 MOA at 600 and 3/4 MOA at 1000 yard since the 1960's. They were a favorite of the US Army and USMC Rifle teams back then.
That's crazy. I can't tell you how many times and in how many ways I googled "1:12 180 grain 30 cal" and all I could find was people suggesting you had to have a 1:10 twist to shoot anything heavier than 165. I guess that shows you what the majority of internet gurus know.

Quote:
is that true, 180 gr hurts or something?
That's relative to what bullet weight you'd be shooting otherwise. Force= Mass x acceleration, and for every action, there is an equal and opposite reaction. Meaning the heavier the bullet, the heavier it hits you in the shoulder.
shredder4286 is offline  
Old December 25, 2012, 12:40 AM   #5
bamaranger
Senior Member
 
Join Date: October 9, 2009
Location: North Alabama
Posts: 4,403
Win M88

My 1956 (grandad's rifle) Win M88 is twisted 1-12" and has always shown an affinity for 150 gr slugs. It shot factory 180 into about 2-1/2", and I shot 180's from it 'cause heavy slugs were a family tradition.

In my late teens I started reading and fooling with rifles a bit and tried factory 150's. Three shot clustes were close to 1" and typically 5 would go into about 1.5". I also felt like the 150's kicked less, which made sense according to Newton.

The old gal is mostly retired now.
bamaranger is offline  
Old December 25, 2012, 04:19 AM   #6
emcon5
Senior Member
 
Join Date: July 10, 1999
Location: High Desert NV
Posts: 1,637
For questions of what twist works for what bullet weight, I always fall back on Dan Lilja's chart, found here:

http://www.riflebarrels.com/faq_lilj...#twist%20rates
emcon5 is offline  
Old December 25, 2012, 08:34 AM   #7
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,052
Dan Lilja's twist chart is pretty good, but for 30 caliber bullets 180 grains and heavier needs some adjustments.

Folks shooting 30 caliber magnums pushing out 190 and 200 grain bullets at about 3000 fps from 1:12 twist barrels in long range matches won a lot of them and set records, too.

I had a worn out .308 Win. Palma rifle 30" barrel cut off 2 inches at the back end, 1 inch of the muzzle end then rechambered for .300 Win. Mag. It shot 180-gr. bullets leaving about 3000 fps about 1 MOA at 1000 yards from its 1:13 twist barrel.

Go figure out why. You may end up learning that the rpm rate a bullet spins is the critical thing about bullet stabilization and accuracy. Faster bullets from slower twists shoot just as accurate as slower ones from faster twists.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is online now  
Old December 25, 2012, 11:11 AM   #8
jmr40
Senior Member
 
Join Date: June 15, 2008
Location: Georgia
Posts: 6,031
It's not the bullet weight that is tied to barrel twist, but bullet length. Generally heavier means longer and a faster twist works better with longer bullets. But there are exceptions. Because of many factors one companies 180 gr bullets may be longer than another companies 180. A 180 pointed bullet and 180 round nose will have very different lengths with very different amounts of the bullet actually in contact with the barrel as the bullet moves through it.

There are no rules written in stone about bullet weight and barrel twist. Only general guidelines.
jmr40 is offline  
Old December 25, 2012, 11:59 AM   #9
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,052
jmr40's absolutely correct for short, blunt and low velocity bullets. For example, consider the .32-40 which was a favorite black powder round for competition over a century ago. For 1:16 twist in one, you should shoot the lighter 150 to 170 grain bullets at those 1400 to 1500 fps speeds. A 1:14 twist is ussually what is required if you wish to shoot 200 grain bullets in a 32 caliber and a 1:11.5 twist is what some are using to shoot 235 grain bullets at less velocity.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is online now  
Old December 25, 2012, 04:49 PM   #10
shredder4286
Senior Member
 
Join Date: May 13, 2010
Location: NE Washington
Posts: 361
Quote:
For questions of what twist works for what bullet weight, I always fall back on Dan Lilja's chart, found here:

http://www.riflebarrels.com/faq_lilj...#twist%20rates
Good reference- thanks for posting that.

Quote:
There are no rules written in stone about bullet weight and barrel twist. Only general guidelines.
Seems to be that way. I'm gonna look and see if I have any load data for a 200 gn bullet just for giggles. Maybe if I feel froggy, I'll order 20 or so just to see how they shoot.
shredder4286 is offline  
Old December 25, 2012, 05:33 PM   #11
Jimro
Senior Member
 
Join Date: October 18, 2006
Posts: 5,588
It's like the 1:9 twist in a 223 shooting the 75 and heavier pills, some rifles can do it and others can't. You never know until you try with your own barrel.

Jimro
__________________
"Gorsh" said Goofy as secondary explosions racked the beaten zone, "Did I do that?"

http://randomthoughtsandguns.blogspot.com/
Jimro is online now  
Old December 25, 2012, 08:27 PM   #12
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,052
jimro, if one barrel with given twist doesn't shoot a given bullet well but another one with the same twist does with that bullet, it ain't the twist's fault. Something else is the problem. Differences between one system and another with something is caused by one or more parts in the one system being different than the other.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is online now  
Old December 25, 2012, 11:01 PM   #13
Jimro
Senior Member
 
Join Date: October 18, 2006
Posts: 5,588
Bart B.

I know what you mean. Most of the folks with 20" HBAR profile barrels or longer have no problem with the 1:9 twist shooting 75-77 gr pills. The guys with the 14.5 inch M4 profile barrels with a 1:9 twist can't get them to shoot for love or money.

Goes back to your point about velocity and a slow twist giving the same RPM stabilization as a lower velocity and a faster twist. Obviously there are barrel lengths between the M4 length and M16 length (16 inch middies and 18 inch SPR profiles come to mind) that are going to need to be tested by their owner to see if they can shoot the heavy pills.

On the internet it is easy for armchair quarterbacks to point out stability formulas, but the only real answer is for someone to go out and shoot to see how their rifle performs. There are some good formulas though, but a lot of the "marginal" stability twists have been winning matches for years.

Jimro
__________________
"Gorsh" said Goofy as secondary explosions racked the beaten zone, "Did I do that?"

http://randomthoughtsandguns.blogspot.com/
Jimro is online now  
Old December 26, 2012, 05:31 AM   #14
trg42wraglefragle
Senior Member
 
Join Date: April 21, 2008
Location: new zealand
Posts: 836
My Tikka in 223 with its 1:8 twist will shoot 40gr vmaxs under 1" at 100yards, in theory it shouldn't work buy in practice it does.
trg42wraglefragle is offline  
Old December 26, 2012, 08:14 AM   #15
old roper
Senior Member
 
Join Date: June 11, 2007
Posts: 1,089
shredder4286, If you looking at Lilja barrel/twist chart remember some of those twist may work with some of the VLD bullets

Matt Kline record 10 shot group 2.815" @ 1000yd shot from 3000WSM used 1/11 twist for Berger 210gr VLD bullet.

I know you posted about shooting some 150gr factory how that shoot? Not sure how much playing with seating depth you tried lot of thing beside twist can effect accuracy.
__________________
Semper Fi
Vietnam
VFW
old roper is offline  
Old December 26, 2012, 10:28 AM   #16
WWWJD
Senior Member
 
Join Date: February 9, 2011
Location: Central KY
Posts: 511
I played with some 190gr SMK in my 1:12 SPS .308 back in the summer. I only worked through one box of 100 of them, but from what I could tell, there was no reason to believe I wouldn't be able to get them shooting sub-moa consistently if I spent some more time working up a load. Put down a few .7 and .8 moa groups if I recall correctly at 300 yards.

Only reason I didn't carry through on this was cost; bought this box at the LGS cause it's all they had at the time (for $35/100) and I figured what the hell. Let's see what happens.

I've got the 168 and 175 pretty much down to a science. Next in line is Berger's 168gr Match Hybrid.

It's all just a big experiment for me; loving it.
__________________
~Mark

NRA fo Life Member
WWWJD is offline  
Old December 26, 2012, 02:32 PM   #17
shredder4286
Senior Member
 
Join Date: May 13, 2010
Location: NE Washington
Posts: 361
Quote:
I know you posted about shooting some 150gr factory how that shoot?
150's shoot very well out of the rifle. They were at about 1/2 moa- and that was just the cheap Winchester super-x.

Quote:
I played with some 190gr SMK in my 1:12 SPS .308 back in the summer. there was no reason to believe I wouldn't be able to get them shooting sub-moa consistently if I spent some more time working up a load
Now that's what I'm talking about. So, once you get a load that shoots half decent, what do you start toying with to get better accuracy? Adjust the seating depth .003" at a time and .1 grain of powder?

I've never messed with the "ladder" technique of working up 5% at a time or whatever it is. I just gradually increased the charge while watching for pressure signs.
shredder4286 is offline  
Old December 27, 2012, 08:03 AM   #18
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,052
For what it's worth, when the .308 Win. was "the" cartridge for NRA com;petition, the two 190-gr. loads that won the vast majority of the matches and set virtually all the records at 600 yards and further was Sierra's 190 HPMK. . .

. . .for bolt guns with custom match barrels, full length sized Winchester case, Rem, Federal, RWS or Win. primer, 42 grains of IMR4064 and the bullet seated to gently seat into the lands.

. . .for service rifles, new LC M118 primed case, 44 grains of IMR4320 and bullet seated about .020" short of the lands.

Most folks shooting Sierra's HPMK bullets in factory match rifles didn't get best accuracy. Those factory barrels were typically too big in groove diameter. Sierra's .3082" HPMK match bullets shot best when the barrel's groove diameter was at least a few 10/000ths smaller; .3079" or smaller. If they used Lapua's 185-gr. .3092" diameter FMJ rebated base match bullets, they shot very well.

I think one should ignore the smallest groups shot when testing a load for accuracy. The smallest ones happen only when all the variables cancel each other out. If you want to see how all the variables contribute to inaccuracy, then use the largest groups for a given load to judge them. Those big ones are the results of all the variables adding up in the same direction. And they show you how much you'll typically miss your point of aim. Any load will sometimes shoot very tiny groups all about the same size, but only a few loads will shoot their largest groups the smallest.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; December 27, 2012 at 08:13 AM.
Bart B. is online now  
Old December 27, 2012, 10:58 AM   #19
old roper
Senior Member
 
Join Date: June 11, 2007
Posts: 1,089
shredder4286, That's pretty good on factory ammo. I only loaded for one factory 308 was Rem 700 and I shot it in factory class local match use 168gr Sierra HPBT match still have my loading data.

I have my own way on how far I want bullets off the lands to start with and Rem SA you are limited to magazine length if you want to use it.

I see your in the Springs are you shooting at Frontier? If you are I load at the range might be able to help you PM if interested.
__________________
Semper Fi
Vietnam
VFW
old roper is offline  
Old December 27, 2012, 03:35 PM   #20
shredder4286
Senior Member
 
Join Date: May 13, 2010
Location: NE Washington
Posts: 361
Old roper- PM sent

Quote:
Any load will sometimes shoot very tiny groups all about the same size, but only a few loads will shoot their largest groups the smallest.
I think I get what you're sayin. Point being- don't always just choose the powder charge that gave you the smallest group, because it may be misleading, right?

Another thing I'm curious about is- how do you know when your bullet is seated out too far? I mean, you have to have it seated in the mouth enough to hold the bullet in, but how far out is too far out?
shredder4286 is offline  
Old December 27, 2012, 04:14 PM   #21
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,052
Shredder, that's right on large vs. small groups. The proof is firing 20, 30 or even 40 shot test groups. Note also that if a given load doesn't produce the same size groups all the time (within 10% extreme spread), you're not shooting enough shots per group to make them at least 90% represent the real accuracy of your stuff as you shoot it.

Your bullet's seated out too far when:

* the round won't fit in and load reliably from the magazine.

* bolt won't close easily on the round as it jambs into the rifling.

* it's not held good enough by the case neck to withstand normal handling and works loose from being seated to shallow.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is online now  
Old December 27, 2012, 07:26 PM   #22
old roper
Senior Member
 
Join Date: June 11, 2007
Posts: 1,089
shredder4286, If you don't get my PM I'll see tomorrow
__________________
Semper Fi
Vietnam
VFW
old roper is offline  
Old December 27, 2012, 08:10 PM   #23
shredder4286
Senior Member
 
Join Date: May 13, 2010
Location: NE Washington
Posts: 361
Quote:
shredder4286, If you don't get my PM I'll see tomorrow
I got your PM- see you then

Quote:
The proof is firing 20, 30 or even 40 shot test groups.
Consecutively, as in- same day, same session?

Quote:
Your bullet's seated out too far when:

* the round won't fit in and load reliably from the magazine.

* bolt won't close easily on the round as it jambs into the rifling.

* it's not held good enough by the case neck to withstand normal handling and works loose from being seated to shallow.
That makes sense. That allows you to seat the bullet .10 or so over COAL listed in the manual so that you can have your bullet touching the lands.

Last edited by shredder4286; December 27, 2012 at 08:16 PM.
shredder4286 is offline  
Old December 27, 2012, 09:42 PM   #24
Jimro
Senior Member
 
Join Date: October 18, 2006
Posts: 5,588
Just to caveat what Bart B said about the 190 SMK through 308 service rifles, the Air Force team had to drill a gas relief port in their M14s to handle the added pressure, which is why that particular modification is still CMP legal for EIC matches. I don't want anyone to take the recipe Bart listed and fire it in a stock M1A thinking that it is fine, odds are they'd get a damaged oprod very quickly.

Brass life with the 190 load was very short (but brass life is generally very short from an M14/M1A platform), but the load did win matches.

With the introduction of the 175 SMK, pretty much everyone has given up on the 190's for High Power/EIC competitions as now they can use a 175 SMK "across the course" load.

Jimro
__________________
"Gorsh" said Goofy as secondary explosions racked the beaten zone, "Did I do that?"

http://randomthoughtsandguns.blogspot.com/
Jimro is online now  
Old December 27, 2012, 11:49 PM   #25
WWWJD
Senior Member
 
Join Date: February 9, 2011
Location: Central KY
Posts: 511
I had mentioned earlier that I had played with the 190; attached is one of the test runs. Group 3 was getting there. If I were to go back and try again, I'd probably start here and work up and down in .2 gr increments. Then play a bit with seating depth in large increments; see if that goes anywhere.
Attached Images
File Type: jpg 190SMK 41 to 44 gr Varget measured a.jpg (155.7 KB, 17 views)
__________________
~Mark

NRA fo Life Member
WWWJD is offline  
Reply

Thread Tools

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 -5. The time now is 08:27 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.13066 seconds with 10 queries