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357 mag dies all the same????

Discussion in 'Handloading and Reloading' started by MGK, Feb 8, 2003.

  1. MGK

    MGK Active Member

    I bought RCBS dies (18212) to reload .357 mag and .38 and these dies are driving me nuts.

    Sized case mouth is .372 OD and .355 ID for a PMG case.

    LSWC bullet diameter = .358

    The cases are different length 1.383 - 1.390"

    The RCBS expander die plug starts out @ .356" and has a length of approximately 1/2" that inserts into the case, then it flares rapidly to .464" over a distance of .300". When you are trying to flare a case mouth from .372" to ~.380" with the way the die plug is configured it is really easy to overexpand the case mouth and endup with a trumpet look and not a nice flare. The crimping die will not accept a case mouth greater than .385", so I have a number of case that need to be resized back to .372".

    Is there something I am missing? Are all 357 dies this way? Do I need to use the expander die? To reload 357, do all cases need to be exactly the same length? What do the rest of you use and do?


  2. braindead0

    braindead0 Well-Known Member

    I'm using RCBS .357 dies with no problems. I do make sure all my brass was at the proper size-to length. I don't bother re-trimming them unless necessary (haven't had to yet).

    You might want to make sure that your sizing die is seating properly as well. Are you using a progressive or single stage press?

    In general, I always expand just enough to just set the bullets into the case straight prior to seating. This cuts down on wear and tear for your brass.
  3. MGK

    MGK Active Member


    I am using a single stage press to get use to reload.

    What type of case length are you using?

    How do you set up your expander die? How much do you expand your case mouth to?

    Any tricks that I should use?

    Thanks MGK
  4. braindead0

    braindead0 Well-Known Member

    I don't recollect the case length, I used the cheat sheet that came with my calipers.

    As I said, I expand just enough, probably about a 16" of an inch of the case is belled.

    If you're getting inconsistant flaring (sounds like you are), make sure the seating surface of the press is clean and the expander plug is firmly secured with the lock ring. Then trim your cases, there should be information in your loading manual(s) for proper case length.

    The cases need to be the same length, and within the min/max for .357.
  5. coonan357

    coonan357 Well-Known Member

    to make it easier to control the adjustment on the belling die I Filed a notch so I can see how far I turned the knob when I set up I have been using these dies for about 4 years now and the only problem was in the initial setup . just like you I overbell some then ground the notch and was able to tune the belling out .
  6. MGK

    MGK Active Member

    Thanks for the suggestions, I'll try getting the case length closer and notching the die for better control.

  7. ArmaLube

    ArmaLube Active Member

    Reloading Dies All The Same?

    It is good reloading practice to try to maintain fairly uniform case length. Keeping the case length consistent allows the expander die to produce uniform results. Belling of the case mouth should be kept to a minimum and usually should be just visible. This will allow bullet seating, without shaving of cast bullets and will place minimal stretching damage to the brass.

    For revolver ammunition, exact case length is not usually critical. But uniformity of case length is important. If you do not have a precision dial caliper, you should obtain one. Then, you will be able to accurately trim cases to the desired length. Some reasonably good dial calipers, accurate to 0.001" are commonly available for under $20.00. Many dial and digital calipers are much more expensive than this, but the high cost models are not really necessary for reloading.

    Simply set the expander die for a minimal amount of case mouth belling, and secure the locking nuts so the setting will be retained (assuming the main die nut has a set screw, or you could lock the main die body using two nuts if necessary). When removed from the press, the adjustments will be retained. Otherwise, the adjustments must be repeated if the die is removed from the press and later re-installed.

    Overall length of .357 Magnum brass is 1.290". There are many places to obtain this information. A source that I like is here:

    The bullet should be a tight fit in the expanded brass case. But, a distinct roll crimp at the case mouth will ensure secure holding of the bullet in the case. The bullets should remain secure under the influence of heavy recoil.

    RCBS makes good reloading dies, as do various other manufacturers. Carbide dies are good for longer die life, but they cost more than the non-carbide variety. Redding dies are highly regarded by most reloaders.

    Good luck!

    "ArmaLube Hits The Mark"

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