The Firing Line Forums

Go Back   The Firing Line Forums > The Conference Center > General Discussion Forum

Reply
 
Thread Tools Search this Thread
Old August 15, 2021, 11:43 AM   #1
Pahoo
Senior Member
 
Join Date: February 16, 2006
Location: IOWA
Posts: 8,389
Rifling; Shallow and Deep

I have a basic knowledge about rifling, but have encountered a variety listings on Shallow and Deep grooved rifling. I have also noticed this in actual bores. I also understand some applications in some firearms but not so much, on others. All have been .....

So I ask; What are the advantages on any particular firearm service. I am primarily addressing new ....

Be Safe !!!
__________________
'Fundamental truths' are easy to recognize because they are verified daily through simple observation and thus, require no testing.
Pahoo is offline  
Old August 16, 2021, 01:09 AM   #2
Geezerbiker
Senior Member
 
Join Date: March 20, 2011
Location: Willamina, OR
Posts: 1,794
For what it's worth and this is far from scientific, but the few rifles I have with shallow micro-groove style rifling seem to shoot just as good as my other rifles with deeper rifling grooves. I suspect it would make more of a difference with softer cast bullets...

Tony
Geezerbiker is offline  
Old August 16, 2021, 06:25 PM   #3
603Country
Senior Member
 
Join Date: January 6, 2011
Location: Thornton, Texas
Posts: 3,828
Based on a one-rifle sample, my Dad’s Marlin 336C (bought about 1962 and never ever bore cleaned) had a 30/30 micro groove barrel that suddenly started shooting 5 gallon bucket sized groups. That suggests that maybe shallow groves rifling has a shorter use life. Maybe…
603Country is offline  
Old August 17, 2021, 06:41 AM   #4
ballardw
Senior Member
 
Join Date: September 19, 2008
Posts: 970
Quote:
Originally Posted by 603Country View Post
Based on a one-rifle sample, my Dad’s Marlin 336C (bought about 1962 and never ever bore cleaned) had a 30/30 micro groove barrel that suddenly started shooting 5 gallon bucket sized groups. That suggests that maybe shallow groves rifling has a shorter use life. Maybe…
I might think more easy to lead up the grooves with sub-optimal ammo choice.
Cleaning might well correct that.
__________________
-+-+-+-+-+-+-+-+-+-+-+-+-+-+
All data is flawed, some just less so.
ballardw is offline  
Old August 17, 2021, 07:36 AM   #5
603Country
Senior Member
 
Join Date: January 6, 2011
Location: Thornton, Texas
Posts: 3,828
I cleaned it, trying to get some accuracy back, but it was too late. We had it rebarreled.

Dad didn’t clean rifle outsides or insides.
603Country is offline  
Old August 17, 2021, 03:12 PM   #6
Hanshi
Senior Member
 
Join Date: April 23, 2017
Posts: 230
For muzzleloaders I like deep rifling, .006" minimum to .016". Modern rifles can be fairly shallow.
__________________
Young guys should hang out with old guys; old guys know stuff.
Hanshi is offline  
Old August 17, 2021, 06:09 PM   #7
BornFighting88
Senior Member
 
Join Date: August 1, 2021
Posts: 127
I second Hanshi. I have 0.007" deep rifling on my flintlock rifle. My winchester 70 has rather shallow rifling and FAT lands.

From my teachings, deep rifling was for soft lead and cast bullets, so it really digs in and imparts spin. Too hard a bullet, and deep rifling just leads to escaping propellant gas.
BornFighting88 is offline  
Old August 18, 2021, 09:46 AM   #8
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 8,667
Jacketed bullets typically shoot most accurate when the barrel's groove diameter is at least a few ten-thousandths smaller than the bullet's diameter.

.309" diameter bullets fired in .308" groove diameter barrels have tested under an inch at 600 yards for ten shots.

Last edited by Bart B.; August 18, 2021 at 10:05 AM.
Bart B. is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 08:04 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2020 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Page generated in 0.07970 seconds with 8 queries