Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Reloading

Reloading Techniques For Reloading


Reply

bullet seating accuracy

 
LinkBack Thread Tools Display Modes
  #8  
Old 08-25-2013, 12:44 PM
Gold Member
 
Join Date: Jun 2006
Location: Shangri-La
Posts: 923
Re: bullet seating accuracy

Quote:
Originally Posted by Mikecr View Post
What is vital to perfect seating though, is rational and consistent seating forces(another thread).
Bingo! Nuff said

What I always found incongruous is how the comparators from Hornady are .011" under caliber while the land size is typically .008" (from what I understand, correct me if incorrect) under.

Example .308 caliber comparator



Seems like if you were looking for a true distance to the lands a comparator that was land diameter would be more appropriate
__________________
If you can read this, thank a teacher.......if you are reading this in English, thank a soldier.
Reply With Quote
  #9  
Old 08-25-2013, 01:31 PM
Platinum Member
 
Join Date: Apr 2005
Location: Alaska
Posts: 3,344
Re: bullet seating accuracy

Quote:
Originally Posted by woods View Post
Bingo! Nuff said

What I always found incongruous is how the comparators from Hornady are .011" under caliber while the land size is typically .008" (from what I understand, correct me if incorrect) under.

Example .308 caliber comparator

Seems like if you were looking for a true distance to the lands a comparator that was land diameter would be more appropriate
Well they've got to be a little smaller than land diameter or the bullet would slide right thru the comparator - no?
Reply With Quote
  #10  
Old 08-25-2013, 01:47 PM
Gold Member
 
Join Date: Jun 2006
Location: Shangri-La
Posts: 923
Re: bullet seating accuracy

No, the bullet is BORE diameter

Example: bullet .308", groove diameter .308", land diameter .300"

So if you made the comparator .300" then it would hit the bullet ogive exactly where the lands would hit it

Right?
__________________
If you can read this, thank a teacher.......if you are reading this in English, thank a soldier.
Reply With Quote
  #11  
Old 08-25-2013, 02:02 PM
Platinum Member
 
Join Date: Apr 2005
Location: Alaska
Posts: 3,344
Re: bullet seating accuracy

Yes, you're exactly right. My bad. My mind replaced groove with land. Sorry.

I always knew my hornady comparators hit the bullet farther from the lands than necessary, and what seemed more desirable. Just never measured them.
Reply With Quote
  #12  
Old 08-25-2013, 02:10 PM
Platinum Member
 
Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,164
Re: bullet seating accuracy

It isn't that simple, and yet simpler still.
Throats are cut at whatever angle the reamer provides. It could be from ~.5 to 15degs.
Bullet noses come in various forms(tangent, secant, hybrid) and radius ~8 to 15degs.
Various combinations change the contact points of both lands AND noses.

You can order your reamer with a throat angle that matches a particular bullet nose.
You can have a comparator made with the barrel stub and same throating from that reamer at barrel finishing. Only this would provide for true contact datum from a comparator.
Change bullets and you negate the efforts.

But it doesn't matter, as a relative datum is typically what we define while discovering most accurate seating distance -with any particular bullet. You can log it, and as long as you always use the same tool & method of measure, then you can reproduce that best seating distance.

I don't pay any mind to where a Sinclair nut contacts w/resp to loaded contact. I'm satisfied as it get's that I can reproduce with the nut whatever I measured with it as best seating.
Reply With Quote
  #13  
Old 08-25-2013, 02:20 PM
Gold Member
 
Join Date: Jun 2006
Location: Shangri-La
Posts: 923
Re: bullet seating accuracy

But the bullets don't really exert back pressure from engraving forces until the bullet actually hits the beginning of the lands

So isn't that the true distance to the lands?
__________________
If you can read this, thank a teacher.......if you are reading this in English, thank a soldier.
Reply With Quote
  #14  
Old 08-25-2013, 04:07 PM
Platinum Member
 
Join Date: Oct 2007
Location: Mountians of SW NC, near Asheville
Posts: 1,596
Re: bullet seating accuracy

Barrels were origionally bored and then rifled. Bore diameter is, by definition, the size hole that gets precisely bored during manufactoring, groove diameter is to the bottom of the rifling. Ergo, a .30 cal barrel is bored to .300" and, with a normal rifling depth of 4 thou, the groove diameter is .308".

Seating a precise amount off the lands isn't the goal, finding the best shooting jump to the lands is but that's a relitive thing,it matters not if we know to the last thou what it really is.

A seating variation of +/- 5 thou rarely matters unless we're seating on a ragged edge of what works well..
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Current Poll
I currently have hunting preference points in the following states

All times are GMT -5. The time now is 08:48 PM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC