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Form fitting a7mm brass to 338 win mag

splatacaster
Has anyone heard of form fitting a smaller caliber like the 7mm mag to a 338 win mag?
I have heard of form fitting before I.E. Ackley Improved and re-chambering in the same caliber etc...but never a smaller caliber to a larger caliber. Is it possible, Is it safey? can you use the brass more than once? What problems dose anyone think could come up.
I would think thining brass, cracks, splits, etc...
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Comments

9 comments

Date Votes
  • llama
    You'll need an expander die, and probably go thru a couple of intermediate steps...

    But then... I gotta ask why? I've seen 338 win mag on the shelf at wally world and many many local gun shops...

    So do you want to do it just because you can? Or do you have a real need?
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  • tsr1965
    Yes it is possible. However, the best way to do this is to neck up the case first, then FIRE FORM. I am not sure why you would need to use 7mm brass for the 338, though, or why you would even want to.

    Best

    EDIT 1

    As other's have said..."If I didn't make it then I don't shoot it".

    I would pass on it.

    Best
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  • splatacaster
    I guess in my efforst to try to keep it short and sweet I left out one important detail. I was looking for brass to reload some 338 win mag and came accross someone on G.B. that has an auction up for 338 win mag brass made from 7mm brass. Hince the questions, is it possible and the main question, is it safe?

    Thanks

    quote:Originally posted by llama
    You'll need an expander die, and probably go thru a couple of intermediate steps...

    But then... I gotta ask why? I've seen 338 win mag on the shelf at wally world and many many local gun shops...

    So do you want to do it just because you can? Or do you have a real need?
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  • charliemeyer007
    Should be fine and safe but Bubba is out there. If the price is good I'd go for it but 200 rounds of new 338 is lots of shooting, years perhaps.
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  • bpost
    quote:Originally posted by splatacaster
    I guess in my efforst to try to keep it short and sweet I left out one important detail. I was looking for brass to reload some 338 win mag and came accross someone on G.B. that has an auction up for 338 win mag brass made from 7mm brass. Hince the questions, is it possible and the main question, is it safe?

    Thanks


    caveat emptor
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  • mrbruce
    If I didnt make it, I sure wouldn't shoot it...
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  • jonk
    It's perfectly fine to open up the neck of a smaller diameter cartridge, so long as the head size is the same, length is close, and if applicable, belt is the same size. I turn scrap 270 Winchester brass into 30-06, 8mm Mauser, etc. all the time- find it by the bucket at my range. I've never done this particular example, but it should work fine.

    I would question the seller as to HOW he did it though- I wouldn't want him to say "oh I heated the whole case red hot and then resized it!"
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  • nononsense
    splatacaster,

    The belted magnum cases make the process of reforming (fire forming) new cases super simple. The belt is the headspace feature for all of these no matter what caliber you want the cartridge to be as an end result. Yours is a good example but it can be as complex as getting .300 Weatherby Mag cases by fire forming .300 H&H cases.

    I personally enjoy case conversion since I work with many more wildcats than standard cartridges. But in the long run, buying case conversions from an unknown source could be problematic. Not always but on occasion. I suggest buying new cases in the caliber or cartridge wanted and let these go to someone else.

    Best.
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  • Riomouse911
    As was posted, yes you can. You can turn any simiar-sized or longer-length belted magnum into another one, either through resizing or fire-forming, and then trimming to proper length. I've seen .375 H&H cases turned into .300 and .358 Norma mags (long case into shorter case), .458 win into .338 win (same length case), etc. I've also shot .300 H&H in a .300 Weatherby, and gotten fire-formed Weatherby cases for Dad's Mark V with no further effort. Some cartridge-case makers even sell full-length unsized belted magnum cases for just this type of stuff.

    Like anything else gun related; if you do it yourself you know how it was done and you take the risk and responsibility. If you buy someone elses' stuff, you're on your own.
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