The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools
Old April 27, 2006, 09:51 PM   #1
flstfi
Member
 
Join Date: March 28, 2005
Location: California
Posts: 44
OAL or Ogive

Case= 6mm Remington
Projectile= Hornady 75gr hp

Using an O.A.L guage and a comparter I determined the maximum overall length to minimize freebore travel. I then deducted .030 from that figure. I then made up a dummy round and chambered it. It went in smooth and there were no marks on brass or copper to indicate any contact.

However the new length does not work well for the magazine in my model 700 Remington.

Is This Normal?????????
flstfi is offline  
Old April 27, 2006, 10:10 PM   #2
garryc
Senior Member
 
Join Date: November 12, 2005
Posts: 2,314
same gig with my 243 remmy.
http://hometown.aol.com/garrywoodsma...age/index.html
garryc is offline  
Old April 27, 2006, 10:18 PM   #3
rwilson452
Senior Member
 
Join Date: June 10, 2004
Location: Tioga co. PA
Posts: 2,358
OAL and magazines

In a word, Yes. Often a cartridge long enough to work properly in the bore will be too long for the magazine. Sad, isn't it. So you need to make a choice. Use your rifle as a single shot to use the most accurate load you can build, or a less accurate load that will fit in your mag. Many factors go into that choice. In my varmint rifles, a singe shot is just fine.

Case= 6mm Remington
Projectile= Hornady 75gr hp

Using an O.A.L guage and a comparter I determined the maximum overall length to minimize freebore travel. I then deducted .030 from that figure. I then made up a dummy round and chambered it. It went in smooth and there were no marks on brass or copper to indicate any contact.

However the new length does not work well for the magazine in my model 700 Remington.

Is This Normal?????????
rwilson452 is offline  
Old April 29, 2006, 06:10 PM   #4
kingudaroad
Senior Member
 
Join Date: March 11, 2005
Location: austin
Posts: 735
Sounds like a hunting situation where you will need the magazine. Even though your chamber will accomodate a longer bullet, your magazine will not. So now you need to determine what the longest oal will fit in your magazine and that length is now the max oal that will function in your rifle. Chances are it will still be over saami reccomended max length and chances are it will still be more accurate as it is still closer to the lands.

I'm kind of surprised though as my remington adl in 270 will accomodate a cartridge that touches the lands.

If you make one that barely fits in the magazine and then make them shorter in increments you can still likely find a sweet spot for your rifle.
kingudaroad is offline  
Old April 30, 2006, 02:39 PM   #5
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,189
Yes to Kingudaroad's point. Not all rifles have a sweet spot .03" off the lands, and it may not be the only one. Pick a load on the light side (a starting load) and fire groups in a round-robin progression in 0.005" depth increments. See if you don't find one around the place where the neck begins to get hold of the most bullet bearing surface?

Nick
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member
Unclenick is offline  
Old April 30, 2006, 03:14 PM   #6
918v
Junior member
 
Join Date: September 25, 2005
Posts: 1,372
Why is it that certain factory loads shoot sub MOA from the magazine? Because freebore is not an accuracyrobber at all, unless your chamber is not concentric with the bore centerline.
918v is offline  
Old April 30, 2006, 04:01 PM   #7
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,189
918v,

Ahh, now you've opened a can of worms. Check Dan Newberry's Optimal Charge Weight theory out. Also look at his instructions for firing 3-shot round robins instead of Audette ladders. Interesting stuff.

Freebore has no reason to affect accuracy if it isn't loose. If it is loose enough to allow a bullet to cant, it will cause trouble, or if your bullet's side bearing surfaces aren't a true cylinder, it will allow canting. Touching the lands is just a way of using the taper and hole centering principle to be certain there is no cant. The conflict is the deeper seating tends to improve start pressure consistency, and improves accuracy for that reason. Seating a little off the lands lets the start pressure improve but also lets the bullet hit the lands at a low enough velocity that it still centers rather than ploughing onto the lead so fast it remains canted. The exact best point of compromise varies with powder burning characteristics.

Harold Vaughn reported that sizing Noslers down half a thousandth improved 300 yard groups from 3.5" to 2.5" in a .270 just by forcing the sides parallel.

In addition, if you have fixed your powder charge, seating depth affects accuracy by changing barrel time. Newberry blames the whole effect on this, but I don't agree. There are cases of the optimum seating depth being found first, then the powder charge afterward. So it is a mix of things. Newberry's ideas are here and fit will with Chris Long's optimum barrel time theory.

Nick
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member
Unclenick is offline  
Old May 1, 2006, 01:20 PM   #8
kingudaroad
Senior Member
 
Join Date: March 11, 2005
Location: austin
Posts: 735
Thanks for the links Nick. Great reading and great information.
kingudaroad 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 07:52 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 0.07604 seconds with 7 queries