Long Range Hunting Online Magazine


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


Reply

Headspacing for 7mm stw?

 
LinkBack Thread Tools Display Modes
  #8  
Old 04-25-2010, 08:30 AM
Gold Member
 
Join Date: Jan 2007
Location: Fairfax County, Va
Posts: 668
Re: Headspacing for 7mm stw?

Quote:
Originally Posted by Loner View Post
The stw belt is the same depth of .2200 but the case is .002 wider from in front of the
belt forward. How would He not know?
What happens to the cartridge case design ahead of the belt has no bearing on the headspace gauge of a belted case. The gauge only measures the depth of the belt.
Virtually all cartridges from the 257 Weatherby thru the 416 Rem Mag are .532 base dia and are 513 just ahead of the belt.
PTG lists ALL belted mags as being interchangable. See line 2.
http://www.pacifictoolandgauge.com/p...t_12_15_08.pdf
If you look at a headspace gauge for a belted case you will see that they are much smaller ahead of the belt that the case would be.
PTG Headspace Go Gage 6.5mm STW - MidwayUSA

Dave
Reply With Quote
  #9  
Old 04-25-2010, 08:44 AM
Silver Member
 
Join Date: Nov 2009
Posts: 134
Re: Headspacing for 7mm stw?

You would want to go one full turn, so that the engraving ends up in the same place. It will make things so much simpler when you set the headspace. I'm not sure what thread pitch on the weatherbys are because I have yet to do one myself. However if it is 16 TPI, (just like the remmys) then that is only .0625 of material that you would remove from the end of the barrel. Not very much at all. I don't think you will notice any difference in cosmetics or in velocity.
Reply With Quote
  #10  
Old 04-25-2010, 10:24 AM
Gold Member
 
Join Date: Apr 2010
Location: NW Mt.
Posts: 600
Re: Headspacing for 7mm stw?

Quote:
Originally Posted by dirtball View Post
What happens to the cartridge case design ahead of the belt has no bearing on the headspace gauge of a belted case. The gauge only measures the depth of the belt.
Virtually all cartridges from the 257 Weatherby thru the 416 Rem Mag are .532 base dia and are 513 just ahead of the belt.
PTG lists ALL belted mags as being interchangable. See line 2.
http://www.pacifictoolandgauge.com/p...t_12_15_08.pdf
If you look at a headspace gauge for a belted case you will see that they are much smaller ahead of the belt that the case would be.
PTG Headspace Go Gage 6.5mm STW - MidwayUSA

Dave
A 257 weatherby is .511 in front of the belt as are 7mm and 300wm and many others. The 300 H&H being the parent case. The STW is off of an 8mm case which is .513.

Last edited by Loner; 04-25-2010 at 10:27 AM.
Reply With Quote
  #11  
Old 04-25-2010, 10:32 AM
Gold Member
 
Join Date: Apr 2010
Location: NW Mt.
Posts: 600
Re: Headspacing for 7mm stw?

Quote:
Originally Posted by tackdriver10 View Post
You would want to go one full turn, so that the engraving ends up in the same place. It will make things so much simpler when you set the headspace. I'm not sure what thread pitch on the weatherbys are because I have yet to do one myself. However if it is 16 TPI, (just like the remmys) then that is only .0625 of material that you would remove from the end of the barrel. Not very much at all. I don't think you will notice any difference in cosmetics or in velocity.
To Add, most barrels (if not all) are not straight, the curve is usually indexed up by
the gun builder. You want that to remain the same if possible. I have had barrels not
turned a full turn because of other constraints and everything was fine, but that is not always the case.
Reply With Quote
  #12  
Old 04-25-2010, 12:32 PM
SPONSOR
 
Join Date: Mar 2010
Location: on the Southern Plains
Posts: 1,091
Re: Headspacing for 7mm stw?

Quote:
Originally Posted by Loner View Post
To Add, most barrels (if not all) are not straight, the curve is usually indexed up by
the gun builder. You want that to remain the same if possible. I have had barrels not
turned a full turn because of other constraints and everything was fine, but that is not always the case.
The case for custom barrels. I just can't see putting money for rechambering into a production barrel, I just wouldn't be satisfied. As far as the caliber designation, I think I would rather have none at all verses the wrong one on there. Picture this! The 7mm Rem. Mag. will chamber in the 7mmSTW, and fire! I don't want to be the shooter or the guy that did the work in that case. If there's no caliber designation at least it says (to me, anyway) that 'something' has been altered, investigate before firing (all barrels should have the proper caliber designation imprinted or engraved on them). I measured a barrel tenon on a Howa 'take-off' barrel, 1.018" dia. , which translates to 25.85mm (a strange number) x 1.5mm. (most likely 26 X 1.5mm).The barrel would advance .0591" per complete turn. The STW really needs a 26" barrel and most factory built 7mm Rem. Mag.'s have 24"barrels. As for the headspace being the same, yes, it is. In theory it sounds good to just "run that STW reamer in until the part that cuts the belt starts to cut. Unfortunately, in practice, you have gone too far by then and the bolt will close on the 'NO-GO' gage and you will be setting the barrel back to correct for proper headspace. If you did stop cutting in time, would the old chamber be completely removed by the STW reamer. Maybe, maybe not. I can't see a manufacture taking the time to install a barrel to its 'curve'. Time and skill cost money, and they need to sell as many rifles as they can for as much profit as they can (they are publicly traded companies). I think they are more interested in profit and liability than quality these days.( my JGS chamber prints show both the 7mm STW and the 7mm Rem. Mag. to be the same diameter, .513", just ahead of the belt)
Reply With Quote
  #13  
Old 04-25-2010, 02:37 PM
Platinum Member
 
Join Date: Jul 2004
Location: Texas
Posts: 5,384
Re: Headspacing for 7mm stw?

Quote:
Originally Posted by shephem View Post
What is the best way to check the headspace when I chamber for the 7mm STW? I was told by a gunsmith that I do not have to set the barrel back, but this is where I get confused. How will I check the headspace since the are both belted mags and would use the same gauge.

Also if anyone has a mag go gauge for sale let me know I need one for another project also.
I would recommend setting the shoulder back 1/4 turn to place the barrel ID under the stock
and re stamp the new caliber correctly.

This will also help clean up the old chamber and throat better.

The head space should be set buy the smith and if you want to buy a go gauge they are only 35.00
to 40.00 dollars and can be used on most standard belted magnums. ( a good tool to have ).

This is also a good time to have the action trued if it has not been done before assembly and head
spacing.

J E CUSTOM
__________________
"PRESS ON"
Reply With Quote
  #14  
Old 04-25-2010, 05:46 PM
Gold Member
 
Join Date: Apr 2010
Location: NW Mt.
Posts: 600
Re: Headspacing for 7mm stw?

You can rent headspace gauges pretty reasonably.


http://www.reamerrentals.com/SearchResults.asp?Cat=26
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Headspacing for 7mm stw?
Thread Thread Starter Forum Replies Last Post
Headspacing 338 Edge nrar15 Gunsmithing 2 08-23-2009 05:59 AM
Need some help with headspacing for a .300 WBY Mag. NorthernWeatherby Reloading 7 06-11-2009 11:03 PM
Headspacing FL Dies? bowhunthard Reloading 10 12-22-2008 02:44 PM
Headspacing ? for Gunsmiths bailey1474 General Discussion 12 06-17-2005 08:33 AM
Headspacing ruger red Rifles, Bullets, Barrels and Ballistics 1 10-24-2003 09:18 PM

Current Poll
In the last 12 months, what was your longest rifle kill on big game?
0 to 200 yards - 25.93%
1,531 Vote
201 to 400 yards - 32.13%
1,897 Vote
401 to 600 yards - 23.10%
1,364 Vote
601 to 800 yards - 10.01%
591 Votes
801 to 1,000 yards - 3.91%
231 Votes
Over 1,000 yards - 4.91%
290 Votes
Total Votes: 5,904
You may not vote on this poll.

All times are GMT -5. The time now is 08:27 PM.


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