.308 win to .243??

troy_mclure · December 21, 2009, 01:14 AM

another case conversion question.

how hard is it to convert .308 win into .243?

its awfully big dia difference to do it in one stage.

how about .308 marlin express?

Tom Matiska · December 21, 2009, 01:31 AM

I've run a fired 308 case through a 243 die, possible but difficult. Less difficult if you run it through your 308 die first. Best way is use a 7-08 die to do it in two steps.

All methods result in a 243 brass with a thick neck that should be reamed.

Crusty Deary Ol'Coot · December 21, 2009, 01:32 AM

The conversion of .308 to .243 is very easy, providing you are using a good lube.

One pass in and out of the die!

Otherwise you can end up stove piping a lot of necks.

STP is a great one for hard sizing jobs, but is the pits to clean up after.

Imperial Sizing Wax should do you a good job.

BUT!!!!!!!!!!!!!!!!!!! And this is important, you must inside ream or outside turn the case necks after forming to .243.

To not do so, puts you at risk of personal injury and/or blowing up a rifle.

Years back, I did the conversion for awhile and lucked out with no problems, until I had a friend provide me with an artical telling about someone blowing up a nice pre-64 Winchester 243.

Made a believer out of me, plus I did see a friend's sako bolt come out of his 243 Ackly Improved in pieces. Extractor etc. and we didn't know just what the problem was except it was clear the pressures were over the top.

AS per the .308 Marlin, I have no experience with that case and without looking at the books just don't know.

Providing the case length is OK and head size matches up to the standard 30/06, 308,243,270, etc. etc. dementions, it might (????) be a possibility.

Keep em coming!

Crusty Deary Ol Coot

troy_mclure · December 21, 2009, 02:42 AM

well the .308 me is a bit shorter than the .308 win.

ill just trade them off, i dont have a reamer, or .243(yet).

Crusty Deary Ol'Coot · December 21, 2009, 04:06 PM

Proper lube IS the key!

I use an old RCBS Rockchucker and even with a poor lube, which leads to damaged or stuck cases, it is no trick to form the .308 to a .243.

As I indicated, one quick stroke, in and out.

HOWEVER, Without the proper lube, you are very likely to loose 25% or more of your cases to "stove piped" necks during the forming operation.

Be careful of over lubing which leads to dimpled cases, just use a small amount of something like the Imperial Sizing Wax and you should have no problem.

Just don't forget to ream or turn those case necks!!!!!!!!!!

Personally I turn the necks as the reaming will not take care of case necks which are overly thick on one or more sides.

You will probably be surprised to see just how uneven the neck thickness is, but it is readily apparent when neck turning.

Keep em coming!

Crusty Deary Ol Coot

December 21, 2009, 01:14 AM	#1
troy_mclure Senior Member Join Date: November 17, 2008 Location: gulf of mexico Posts: 2,716	.308 win to .243?? another case conversion question. how hard is it to convert .308 win into .243? its awfully big dia difference to do it in one stage. how about .308 marlin express? __________________ There is only one tactical principle which is not subject to change. It is to use the means at hand to inflict the maximum amount of wound, death, and destruction on the enemy in the minimum amount of time."

December 21, 2009, 02:42 AM	#4
troy_mclure Senior Member Join Date: November 17, 2008 Location: gulf of mexico Posts: 2,716	well the .308 me is a bit shorter than the .308 win. ill just trade them off, i dont have a reamer, or .243(yet). __________________ There is only one tactical principle which is not subject to change. It is to use the means at hand to inflict the maximum amount of wound, death, and destruction on the enemy in the minimum amount of time."

December 21, 2009, 01:31 AM	#2
Tom Matiska Senior Member Join Date: April 12, 2000 Location: Wilkes-Barre, Pa Posts: 1,029	I've run a fired 308 case through a 243 die, possible but difficult. Less difficult if you run it through your 308 die first. Best way is use a 7-08 die to do it in two steps. All methods result in a 243 brass with a thick neck that should be reamed.

December 21, 2009, 01:32 AM	#3
Crusty Deary Ol'Coot Senior Member Join Date: November 19, 2009 Location: Deary, Ideeeeeeho Posts: 531	The conversion of .308 to .243 is very easy, providing you are using a good lube. One pass in and out of the die! Otherwise you can end up stove piping a lot of necks. STP is a great one for hard sizing jobs, but is the pits to clean up after. Imperial Sizing Wax should do you a good job. BUT!!!!!!!!!!!!!!!!!!! And this is important, you must inside ream or outside turn the case necks after forming to .243. To not do so, puts you at risk of personal injury and/or blowing up a rifle. Years back, I did the conversion for awhile and lucked out with no problems, until I had a friend provide me with an artical telling about someone blowing up a nice pre-64 Winchester 243. Made a believer out of me, plus I did see a friend's sako bolt come out of his 243 Ackly Improved in pieces. Extractor etc. and we didn't know just what the problem was except it was clear the pressures were over the top. AS per the .308 Marlin, I have no experience with that case and without looking at the books just don't know. Providing the case length is OK and head size matches up to the standard 30/06, 308,243,270, etc. etc. dementions, it might (????) be a possibility. Keep em coming! Crusty Deary Ol Coot

December 21, 2009, 04:06 PM	#5
Crusty Deary Ol'Coot Senior Member Join Date: November 19, 2009 Location: Deary, Ideeeeeeho Posts: 531	*Proper lube IS the key!* I use an old RCBS Rockchucker and even with a poor lube, which leads to damaged or stuck cases, it is no trick to form the .308 to a .243. As I indicated, one quick stroke, in and out. HOWEVER, Without the proper lube, you are very likely to loose 25% or more of your cases to "stove piped" necks during the forming operation. Be careful of over lubing which leads to dimpled cases, just use a small amount of something like the Imperial Sizing Wax and you should have no problem. Just don't forget to ream or turn those case necks!!!!!!!!!! Personally I turn the necks as the reaming will not take care of case necks which are overly thick on one or more sides. You will probably be surprised to see just how uneven the neck thickness is, but it is readily apparent when neck turning. Keep em coming! Crusty Deary Ol Coot