Can u re-size a 7.62 mm to .243

Question

i got a heap of used shells with the markings MF 70 L2A2 im quite sure their Australian army 7.62x51 mm re sized to .243 but i want to be sure

Answer 1

The other answers are correct, but need a few details added. First, be sure the cases aren't Berdan primed, which isn't worth the trouble to deal with. Second, resizing down this far probably means the neck thickness is too thick, and needs either reaming or outside-turning. Google "Forster" for a good reaming jig. If things don't work out, buying a big "lifetime supply" of new brass mailorder gets the piece-price down, and that is probably the cheapest way to go overall. Regards, Larry.

Answer 2

That's how the originals were done. As usual with reloading military cases, capacities may be smaller than the civilian counterparts, so work up loads carefully.

Answer 3

I am a ballistics technician

Yes you can.  No - you do not want to.  Unless civilization has totally fallen and you happen to have all the proper tools and dies handy.......  

Military brass is thicker than standard civilian brass.  You would need to re-form the case - and - then ream the case mouth.  This being military brass - thicker - it will require more force to re-form and more work to ream.  Good chance you will need to anneal them as well with a torch.  You will probably ruin 40-90 cases before you get it right.

The second issue with military brass is the requirement to also remove the primer crimp.  Another die set, another process.

Best to either sell the brass on ebay for what it is and put the $$ toward new 243, or, find somone to trade with.

Hope this helps

Answer 4

The parent case of the .243 Win is most definitely the .308 Win, aka 7.62x51mm NATO.

I believe you can form the cases with a single pass through a .243 Sizing die.  I form .358 Win bras vrom .308 Win brass with a single pass and lots of case lube.  BUT, it might be a better idea to use an intermediate step between .308 and .243.

I'd suggest you check with RCBS about forming .243 from .308 brass.  Another option would be to call the Sierra bullets reloading hotline, the can give you plenty of info on reloading at no charge.

Doc

Answer 5

I think RCBS makes a forming die to do it, but they are like $600 last I heard. Otherwise, numerous sites confirm that .308 is the parent case for .243

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"The Handloader's Manual of Cartridge Conversions" says you can form .243 cases from .270 cases, and in theory the .308 Winchester should work, too

http://www.thehighroad.org/showthread.ph...

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"The 243 (6mm) Winchester is nothing more than the 308 Winchester case necked down."

http://home.swipnet.se/longrange/SNIPER%...

. . .  . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  ". . . and because it was created by simply necking down the 7.62mm NATO case."

http://www.chuckhawks.com/243_service_ri...

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . "The 243 (6mm) Winchester is nothing more than the 308 Winchester case necked down."

http://www.reloadbench.com/cartridges/24...

Answer 6

The 7.62 NATO (AKA .308) is the parent cartridge of the .243 so the case can be resized to .243.  From the shoulder to the base, the cases are exactly the same including the angle of the neck.  All you would need to do is to reduce the size of the neck to .243 and trim to the proper length.  I am pretty sure that you can do this with the regular .243 sizing dies.  The secret is to first resize them to .308 caliber.  This will take less force and gete them started on their journey to becoming .243 rounds.  Next, you will need to resize the necks to .243.  Check to see that each case is properly lubricated but not over lubricated.  This is important!!!  If the case does not have enough lubricant, it can become stuck in the die and be a problem.  Be sure to have a stuck case remover on hand whenever resizing cases.  Without a stuck case remover, if a case becomes stuck in the sizing die, you will be shut down until you can remove it.  If you try to pry it out, you can damage your resizing die beyond repair.  Anyway, once you have made sure that the case is properly lubricated, run it up into the resizing die until it makes contact, then ease it on inot the die until significant resistance is felt.  Draw it back and restart.  Keep this incremental insertion until you have run the case  fully into the resizing die.  The secret is to resize the neck in several steps instead of trying to do it all in one stroke.  The single stroke method often results in wrinkled, dented or stuck cases.  Once all of the cases are resized to .243, you will need to trim them to length and chamfer the mouths.  Wipe off the left over lube and you have a pile of new .243 cases.  Whenever I have resized cases to another caliber, the first thing I do before loading them up for use, is to put a light load in them and shoot them to fire form them to your rifle chamber.  It is a good way to get rid of any old bullets (who cares of they hit the target, you just need to fire form the shells).  If you don't have any old .243 bullets, you can buy some cheap bulk bullets or use some cast bullets (with the proper load, of course).

I hope this helps.  Good luck to you.