can I convert 338 win mag to 300 win mag?

[hillbillydruggist]

I sold my 338, and now I have a lot of brass, can I do this? don't they have the same parent cartridge?

thanks

 

[Doug Beach]

Won’t work. .338wm is shorter than .300wm.

 

[tclaunch]

It can be necked to 7mm for 7 Rem mag

 

[alinwa]

Well, TECH'nically........ "yes"

But;

-You will have to anneal first, not an easy nor free endeavor and,
-your resultant cases will have a wicked gapspace, like 1/8th inch for carbon and crud to collect.
-(OPINION ALERT!!) this gap space is so big that IMO the bullet will expand into the gap upon obturation causing pressure swings.

I make a ton of brass..... I'm cheap, and........ I wouldn't do it.

Unless,




Zombie 'Pockalips......... THEN ya's do what'cha' gotta' do to get'cher WhackaMole on.....

 

[bpd459]

Greetings,
How about the .30/.338?? It certainly won its share in the "old days".
Good luck,
John

 

[ShootDots]

Well, TECH'nically........ "yes"

But;

-You will have to anneal first, not an easy nor free endeavor and,
-your resultant cases will have a wicked gapspace, like 1/8th inch for carbon and crud to collect.
-(OPINION ALERT!!) this gap space is so big that IMO the bullet will expand into the gap upon obturation causing pressure swings.

I make a ton of brass..... I'm cheap, and........ I wouldn't do it.

Unless,




Zombie 'Pockalips......... THEN ya's do what'cha' gotta' do to get'cher WhackaMole on.....

Hello Al! I am quite certain I don't have the experience, especially in larger cases, that you probably have. But I do have a question: I have fireformed many, many cases, albeit 6mmBR into Dasher brass. You have to blow the shoulder forward 100 thousandths AND make a 40 degree out of it. There is no ill-effects from blowing that shoulder a considerable ways forward! The question: After necking the case down and turning the case neck to fit the new chamber, why would blowing the case shoulder forward be any different on the "old" .338 case to the "new" .300 Win Mag case? This one escapes me..

 

[tclaunch]

Well, TECH'nically........ "yes"

But;

-You will have to anneal first, not an easy nor free endeavor and,
-your resultant cases will have a wicked gapspace, like 1/8th inch for carbon and crud to collect.
-(OPINION ALERT!!) this gap space is so big that IMO the bullet will expand into the gap upon obturation causing pressure swings.

I make a ton of brass..... I'm cheap, and........ I wouldn't do it.

Unless,




Zombie 'Pockalips......... THEN ya's do what'cha' gotta' do to get'cher WhackaMole on.....

Not sure I understand where the gap would be. The 338 Win Mag is the parent case of the 7mm Rem Mag, both the same length. I think your a bit confused.

 

[alinwa]

Hello Al! I am quite certain I don't have the experience, especially in larger cases, that you probably have. But I do have a question: I have fireformed many, many cases, albeit 6mmBR into Dasher brass. You have to blow the shoulder forward 100 thousandths AND make a 40 degree out of it. There is no ill-effects from blowing that shoulder a considerable ways forward! The question: After necking the case down and turning the case neck to fit the new chamber, why would blowing the case shoulder forward be any different on the "old" .338 case to the "new" .300 Win Mag case? This one escapes me..

I didn't mention the shoulder, the shoulder isn't any sort of problem. In simple fact, to properly form ANY case you need a headspacing shoulder and in the case of 338WinMag down to 300WinMag this part of the equation is automatic..... you just neck the big 338 down to a tight crush-fit and BaDaBOOM! Perfect cases....BUT,

338 case starts out an eighth inch too short. THIS you can't fix. Winchester did this on purpose. All the companies have to come up with ways to keep ammo from being mixed up and fired in the wrong guns. Another example is the "338 Edge" which, technically IS NOT a 338RUM as it must be made from longer 300RUM cases.

And, being fired brass, it must be annealed before you can neck the new headspacing shoulder into it. If you try just neck it down it'll collapse the shoulder. You might get some of them to work since the move is small, but for brass to be worked properly it need be annealed between moves. Then you'll lose more of them blowing them back out. I've necked cases down from 300 to .22 in a series of steps and found you need to start with new cases, then anneal a couple times in the necking-down process.

This whole shouldering thing is specifically why the original DAsher is so friggin' 'genius...... You start with new 6BR cases, neck them to .22 to form a beauteous crush-fit shoulder and blow them out in one fell swoop..... POP!..... done. DEAD straight cases....

Then the bastard step-child "6MM Dasher" came around and only rarely are they made using crush-fit.

 

[ShootDots]

Oh okay... I did not know the finished case was 1/8th short.. Thank You.. I appreciate it..