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Thread: Revisit - 9mm Brass to .308 Jackets

  1. #21
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    Mustang,

    Very familiar with the RBT die set, I have many of them. Fun fact you might not know and Corbin isn't anxious for others to figure out. The RBT2 die is the same as an ordinary core seat die, except that it has a RBT internal punch. So, it's not necessary for you to spend $250 for a new die, just get on Corbin's website and order a $50 flat based internal punch, and it will work perfectly with your RBT2 die. When I order a new set, I get the extra punch straight out of the gate. When you order, just put in the instructions that you want the punch to go with an existing RBT2 die for seating flat based bullets. They will hook you right up!

    Further, I think you are approaching the limits of what can be done with a hand press. On a hydro, with the proper rounded punch and draw die, that 9mm brass would be completely drawn, perfectly centered and ready for the next reduction. How many draws are there in your kit? Does it draw it down in one pass, or are there several? Conventional wisdom Corbin uses is you can draw down 80% from one pass to the other. So, a 9mm base, in theory could be drawn from .391 to .312 in one pass, so I'm guessing this is done with two draws.
    Last edited by Zbench; 07-03-2018 at 10:53 AM.
    Zbench

  2. #22
    Boolit Master



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    The 9mm to .308 is accomplished in One Draw on the Corbin die set (there is only one draw die). I use the CSP-1 hand press for my Swaging operations. As you mention; this is much more difficult than their hydro press would be. To accomplish the drawing down of the 9mm to .308 jackets I do the following.

    (a) Anneal each case in the flame of a 1lb propane tank with the small screw on torch; heating until the entire case is bright glowing orange (15 to 25 seconds depending on how far open the valve is). This is critical - under annealing makes it almost impossible to draw the 9mm into a jacket; and could result in damages dies and significant wear to the press.

    (b) Place an annealed and lubed case onto the bottom punch and light lube on the punch top area. Screw the die into the top threads ~ 6 full turns. I have an index mark scratched into the top Punch Holder so I can count turns when setting dies (Supports rapid set up when I change to different dies. I keep a spread sheet with # of turns required for different die operations, different weight cores, different nose punch setting, etc... Works great to immediately get to a set up - then if required a 1/16 turn up or down to tweak the setting to "Just Right"). I cycle the swage press; which runs the 9mm case into the die and it remains "Stuck" inside the die with the bottom punch pulling out as the ram returns to the down position.

    (b) Turn the die in 2 or 3 turns; cycle the press driving the 9mm case further into the die.

    (c) Turn the die another 2 or 3 turns, driving the case further into the die.

    (d) Continue until the die is as low as it will go; cycling the press after each 2 to 3 turns into the threads.

    (e) Unscrew the die back to where ~ 6 turns of thread is engaged. (You need about 6 full turns into the threads to make sure one does not damage/rip out the threads of the press).

    (f) Repeat. The 1st case will be pushed out the top as one continues to cycle the 2nd case through incremental sizing.

    The resistance in sizing this way is much, much easier than trying to draw the case with one cycling action.
    Mustang

    "In the beginning... the patriot is a scarce man, and brave and hated and scorned. When his cause succeeds, the timid join him, for then it costs nothing to be a patriot." - Mark Twain.

  3. #23
    Boolit Master



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    Dropped by the range this afternoon. I had seven .308 Winchester PMC brand cases, primed with Remington 9 & 1/2 Rifle Primers, 44.5 grains of BLC-2 powder. The seven bullets were 148 grains, swaged from the 9mm to .308 jackets. All appeared to be ~ square visually inspected. Bullets are an 8S ogive. Seven round group was just slightly less than 3MOA Grouping at 100 Yards (2.947 MOA):

    Click image for larger version. 

Name:	9mm drawn to 307 jackets - squared base - compressed - Group Size.JPG 
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    Mountain Prepper provided what appears to be a three shot group using bullets made from 9mm to .308 jackets which appears to me to be about 3.5 MOA. The picture of the group s found at post #15, link: http://castboolits.gunloads.com/show...to-308-jackets .


    The best (Only other) published group I have found for bullets made from 9mm Brass was from Cane_Man's thread on making dies for a 7mm. He was able to achieve a 0.642 MOA group in his self made dies using a 7mm Bullet made from 9mm brass, see post #179 in the following thread.
    http://castboolits.gunloads.com/show...Cal-Dies/page9

    Based on the long thread by Cane_Man; it appears to me that a different approach may still yield a 9mm to .308 jacket that will shoot much better (than what I achieved this afternoon) is possible; but will take additional efforts and different punches in the drawing process.
    Last edited by MUSTANG; 07-03-2018 at 10:16 PM.
    Mustang

    "In the beginning... the patriot is a scarce man, and brave and hated and scorned. When his cause succeeds, the timid join him, for then it costs nothing to be a patriot." - Mark Twain.

  4. #24
    Boolit Master tiger762's Avatar
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    I used to do this for sizing down 45acp to make 458 and sizing down 380 to make 9mm bullets. Instead, what I do now is set the die such that the first throw of the handle will size the first 3/8" of brass length, sufficient to size down the case head. Then, I withdraw the ram and sit various length ground dowel pins on top of the punch, guiding them up by hand until it is inside the die, then push the ram the rest of the way in. By doing it this way it eliminates having to keep adjusting the die.

    45acp brass takes a total of three throws of the press handle (punch, punch plus 3/8" ball bearing, punch plus 2" dowel pin)
    45acp aluminum takes two throws of the press handle (punch, punch plus 1.5" dowel pin)
    9mm brass takes three throws
    380 brass takes two throws

    Quote Originally Posted by MUSTANG View Post
    (b) Turn the die in 2 or 3 turns; cycle the press driving the 9mm case further into the die.

    (c) Turn the die another 2 or 3 turns, driving the case further into the die.

    (d) Continue until the die is as low as it will go; cycling the press after each 2 to 3 turns into the threads.

  5. #25
    Boolit Master



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    Yes; I've used the steel dowel concept also. Found my fat fingers, coupled with difficulty in catching the steel dowel before it fell to the floor was a problem off and on. It was easier to simply screw the die in and out as described. Takes longer; but... We all adapt processes that are easier (or seem so) for our own purposes.
    Mustang

    "In the beginning... the patriot is a scarce man, and brave and hated and scorned. When his cause succeeds, the timid join him, for then it costs nothing to be a patriot." - Mark Twain.

  6. #26
    Boolit Master


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    Mustang

    Cannot offer any advice but a 3 MOA group at least shows promise!

    Good luck
    Don Verna

    NRA Endowment Member

  7. #27
    Boolit Master

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    I shot a 10 round group yesterday. Remington R-25 (ar-10) solid rest, decent scope.
    The group was five minutes high and wide.
    Eight rounds went into three minutes.
    This rifle has never been a tack driver like a couple 700 remingtons hanging around here.

    If swaging the perfect bullet was easy, it might be boring.
    To lazy to chase arrows.
    Clodhopper

  8. #28
    Boolit Man
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    More Observations:

    I am starting to think my Dies have just as much personality as some of my Guns. But I am still a long way from the Accuracy Dept.
    Punching out a bunch of 9mm cases for 357 projectiles, with absolutely no problems. If there is any angle to the base after I cant see it with my readers on. But I notice that as long as I can get the primer flash hole over the nipple on the end of the reducer punch, it does not matter weather I straighten it or let it hang crooked. When the case enters the Die, it straightens itself out like it hits a shelf before pressure reduces diameter. This in not always the case with my 9mm-308 Die. So I am wondering if the geometry of the die is partly to blame for crooked bases after reduction. And sometimes, the primer hole is too small for my punch to enter so I just insert the case into the die ahead of the punch and let the die center the case on the punch. Have you tried that ?
    Another thing that came to mind is that I once accidentally dropped one of my dies and bent the extractor punch and had to get a new one, is that a possibility for you. That could explain crooked bases if the punch isn't straight with the Die.
    Also, I did a little experiment and took half a dozen of the 9mm-357 case/jackets and ran the through my 9mm-308 die, with very little to no angle on the bases. That looks very promising for me, the primer being the only issue because it does not reduce like the rest of the case and protrudes. Looked good enough to pull the trigger and at least try a few that way to see how they shoot.
    Have you contacted Corbins ? Dave or BT Sniper would be good places to ask question. Both Dave and Brian have been good sources of information for me.

    Don't Stop now, I'm still interested in how you work out the bugs.

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check