Re-sizing .243win to .308win

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  • Re-sizing .243win to .308win

    Gday,

    I own both cal's listed but have had my .243 for over 15 years... Over those years I have accumulated a heap of .243 brass but not so many .308 cases.

    Is it worth me re-sizing .243 to .308?

    If so what are the appropriate steps in re-sizing the cases other than running them through a .308 FL die...

    Is fire forming necessary?
    Annealing the necks?
    Neck Reaming?

    Cheers....

  • #2
    Hi never done the 243 to 308 but do the 308 to 243 I use heaps of lube on the case and size it in sections and slow just try a few sound like you have been reloading for a while trust your skill

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    • Guest's Avatar
      Guest commented
      Editing a comment
      I used 243 Lapua cases in my 7mm-08 and you could not size them up in one pass even with a tapered neck expander, every time I tried I would just push the neck into the shoulder of the case trashing it. I had to go from 243(6mm) to 6.5 to 7mm for it to work and even then some of the necks would end up pushed in.

      The only way to do it is to fireform those 243 cases using the cream of wheat method.

      That involved priming the 243 case adding 5 grains of really fast powder(I used an old shotgun powder), carefully filling the rest of the case with cereal. I used a fine baby cereal at first but uncle toby's oats works(its really only a filler) Then you seal the case necks with candle wax and fire them in your rifle and I got perfectly formed 7mm-08 cases formed to my chamber.

      That method would be the only way I would go from 243 to 208.

    • Spurious
      Spurious commented
      Editing a comment
      Yeah, it can be done. Plenty of lube on the inside of the neck, and take it easy. You may find the neck thickness a little on the low side, and the number of reloads you get may be less than desired.

      But you've got to consider selling the 243 cases as they are, and buying 308s as they are. It would be easier.

      And I like the idea of Tumbo's with the cereal/wax method.

  • #3
    You must have a lot of 243 cases to go to that much trouble. I would sell or cash some in as Spurious said.

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    • Spurious
      Spurious commented
      Editing a comment
      Yep. Once fired 243 cases are quite sought after.

  • #4
    Originally posted by butta9999" post=16926
    Gday,

    I own both cal's listed but have had my .243 for over 15 years... Over those years I have accumulated a heap of .243 brass but not so many .308 cases.

    Is it worth me re-sizing .243 to .308?

    If so what are the appropriate steps in re-sizing the cases other than running them through a .308 FL die...

    Is fire forming necessary?
    Annealing the necks?
    Neck Reaming?

    Cheers....
    Have you tried one or how do you plan to go about it.

    Not something I have done or interested in but I thought after a quick look at the cartridge diagrams ....is the expanded .243W case going to be way short in length of the .308W case, hard to work out since the shoulder angle is so different. I know that the .243W was developed from the .308W but also might have had it's length trimmed so that's something you can't get back and you don't want cases that are short of proper length.

    If I was going to do one I would use my K&M 6mm to .30Cal Expander Mandrel that I use to produce 30BR from a 6mmBR Case.

    I would certainly think they would have to be Fire Formed since the shoulder angle goes from 20-40 degrees . Would be interesting to see the results.

    I have old .243W cases I could expand and try but I do not have a .308W FLS Die to adjust the case body and shoulder angle nor anyone I know I could borrow one.

    If I can be of any help let me know.

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    • Guest's Avatar
      Guest commented
      Editing a comment
      Thanks Lindsay i'll be sure to let you know and thanks others for weighing in on this topic...

      I might run a couple through the .308 die and see what the measurements come out like.

      It's more of something to do for learning purposes rather than needed the .308 brass. Yes it does make sense to sell or swap some cases but I like seeing peoples ideas and then learning from them...

      One question "Tumbo" whats it like later cleaning out the barrel from all the cereal and candle wax?? Do you fill the case to the top with the cereal then put a blob of wax on top?

      Cheers..

  • #5
    Gday,

    Here is a picture of my attempt of running a .243 case through a .308 FL die. First case which is split down the middle was Winchester Brass.

    Second Case is Federal Brass and sized quite easily using graphite powder on the inside of the case mouth and using case lube on the exterior case wall. Where I am pointing with the Allen key there is a slight bulge on the bottom of the neck. Will Fire forming the case remove this bulge?

    I measured the case and it measures exactly 2.015 inches which is 10 thou off recommended trim length of 2.005 inches for the .308win case.

    Mega: I am little confused on the angle of the shoulder you quoted in your post. In my book it shows the angle of the shoulder for the .243 and .308 to be 20 degrees. Am I missing something here?

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    • #6
      Sorry, I was in a hurry reading cartridge diagrams. Yes they are both 20 degrees. The .243W Diagram I have shows 20 degrees but the .308W was both sides of the shoulder so read 40 degrees. I should have tweaked earlier that the .308W didn't look steep.

      I tried an old .243W case but it was really old and the neck did exactly the same as your first one even though it was well lubricated inside. A case from back in the 1970's so I didn't expect much. It should have been freshly annealed to soften the neck.

      The bulge might blow out or at least even out after fire forming. Only one way to find out as long as it chambers okay.

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      • #7
        I have some trail boss powder and some cast bullets my mate uses to reload subsonic rounds for his .308. I might load 5 of them with 5.5gr of Trailboss and see if I can rid of that buldge...

        I was surprised of the case length after sizing to .308 so that's a plus....

        Or I could try the cereal method.

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        • #8
          I think you may need a rather stiff load, not mild load in order to create enough pressure to blow the case out properly for fire forming.

          Not quite the same but I had a bit of drama recently fire forming my 6mmBR expanded to 30BR as the first one's I did had not formed at all. I made two mistakes by not seating bullets on the lands and too small a powder charge (only 2gr under) to enable pressure to build up enough to blow the case out. BTW, the 30BR is very kind on cases and they do not show any change in dimensions after multiple firings.

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          • #9
            I think I might start light first and if that does not work then i'll re-visit and see whether its a viable option....

            I don't see how the cereal method could work then if I am suppose to seek higher pressures for fire forming.

            Anyway experiment time.

            Results to follow...

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