Long Range Hunting Online Magazine


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


Reply

Reamer design for 338 Norma Mag for 250gr Berger

 
LinkBack Thread Tools Display Modes
  #1  
Old 03-05-2013, 06:55 AM
Junior Member
 
Join Date: Aug 2011
Posts: 26
Reamer design for 338 Norma Mag for 250gr Berger

Hi guys

Can some perhaps assist me with a reamer design for 338 Norma Mag for 250gr Berger? I have no luck getting hold of the guys at PTG or Manson to assist me.

Regards
Reply With Quote
  #2  
Old 03-05-2013, 08:03 AM
Platinum Member
 
Join Date: Jul 2004
Location: Texas
Posts: 5,624
Re: Reamer design for 338 Norma Mag for 250gr Berger

Quote:
Originally Posted by Machann View Post
Hi guys

Can some perhaps assist me with a reamer design for 338 Norma Mag for 250gr Berger? I have no luck getting hold of the guys at PTG or Manson to assist me.

Regards

Why not just buy a SAMME reamer and adjust the round for the chamber instead of building
the chamber around a Bullet.

If the barrel does not like the Berger your stuck. with a standard chamber that has been tested
by the designer you have the best chance to have an accurate rifle with several different bullets.

I prefer the extended magazines that allow a round to be seated long instead of having to single
load them.

Just an opinion,

J E CUSTOM
__________________
"PRESS ON"
Reply With Quote
  #3  
Old 03-05-2013, 08:42 AM
Junior Member
 
Join Date: Aug 2011
Posts: 26
Re: Reamer design for 338 Norma Mag for 250gr Berger

Thanks JEC!

Please help.

The reason why I'm asking is because according to me the difference in length between the 300gr and 250gr Berger is .22 which wil require me to seat the 250 gr bullet outside the optimum range in the case or have a massive jump? If you consider the Lapua and Sierra and Berger they are all approximately the same length and result in the same COAL. My assumption is that you will still be in range for the the other 250gr bullets? Please, I'm no expert and some expert help will really be appreciated

Thanks
Reply With Quote
  #4  
Old 03-05-2013, 09:50 AM
Platinum Member
 
Join Date: Jul 2004
Location: Texas
Posts: 5,624
Re: Reamer design for 338 Norma Mag for 250gr Berger

Quote:
Originally Posted by Machann View Post
Thanks JEC!

Please help.

The reason why I'm asking is because according to me the difference in length between the 300gr and 250gr Berger is .22 which wil require me to seat the 250 gr bullet outside the optimum range in the case or have a massive jump? If you consider the Lapua and Sierra and Berger they are all approximately the same length and result in the same COAL. My assumption is that you will still be in range for the the other 250gr bullets? Please, I'm no expert and some expert help will really be appreciated

Thanks
I don,t consider my self an Expert ether, just with 50 + years experienced and know that Free bore is not the enemy, chamber dimensions are. I don't have a SAMME spec. for the new 338 Norma mag but if memory serves me you should have about .200 thousandths free bore.

The 250 grain bullet has a long enough body to reach the lands and still have plenty of bullet
engagement in the neck the 300s will have to be seated deeper if you shorten the free bore.

I don,t want to talk you out of a custom reamer, just warn you about the problems that come with it.

For velocity, free bore is your friend, for accuracy with free bore the chamber, especially the head space
is also your friend.

You don,t have to touch the lands to get accuracy.

J E CUSTOM
__________________
"PRESS ON"
Reply With Quote
  #5  
Old 03-05-2013, 01:11 PM
SPONSOR
 
Join Date: Mar 2010
Location: on the Southern Plains
Posts: 1,205
Re: Reamer design for 338 Norma Mag for 250gr Berger

Quote:
Originally Posted by J E Custom View Post
I don,t consider my self an Expert ether, just with 50 + years experienced and know that Free bore is not the enemy, chamber dimensions are. I don't have a SAMME spec. for the new 338 Norma mag but if memory serves me you should have about .200 thousandths free bore.

The 250 grain bullet has a long enough body to reach the lands and still have plenty of bullet
engagement in the neck the 300s will have to be seated deeper if you shorten the free bore.

I don,t want to talk you out of a custom reamer, just warn you about the problems that come with it.

For velocity, free bore is your friend, for accuracy with free bore the chamber, especially the head space
is also your friend.

You don,t have to touch the lands to get accuracy.

J E CUSTOM
+1 at that!
__________________
"Shoots real good!": definition; it didn't blow-up in my face. Not everything can be fixed on an internet forum!
Reply With Quote
  #6  
Old 03-05-2013, 10:42 PM
Platinum Member
 
Join Date: Dec 2009
Location: NW MT
Posts: 2,668
Re: Reamer design for 338 Norma Mag for 250gr Berger

why not the 300 gr. for which it was designed.And will out fly it and out energy it at long range
Reply With Quote
  #7  
Old 03-06-2013, 12:13 AM
Junior Member
 
Join Date: Aug 2011
Posts: 26
Re: Reamer design for 338 Norma Mag for 250gr Berger

JEC I would consider +50 years of experience a expert.

The amount of experience you guys are blessed with over there is huge compared to what we have over and thanks for sharing. We don't have the powder over here to push the 300gr bullets fast enough, will be able to get 2650fps max out of the 300gr vs. 2950fps on the 250gr. That is a 7MOA drop difference at 1500m.

Iím looking to build this rifle as accurately as possible. An old bench rest legend over here designs all his reamers so the bullet kisses the lands with the base of bullet bearing surface between 0.02-0.07 above the intersection of the case neck and shoulder. Thus my thinking behind the reamer design. If you seat the Berger 250gr correctly you have close to a +0.22 jump in a chamber designed for the 300gr Berger kissing the lands. Is this too much jump to get optimum accuracy out of the rifle?


Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes



All times are GMT -5. The time now is 03:07 AM.


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