The Original CZ Forum
GENERAL => Ammunition, questions, and handloading techniques => Topic started by: Clint007 on July 04, 2016, 11:22:40 AM
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What's the core value of an undersized resizing die for pistol calibers like 9mm? I reload just for me for a variety of 9mm pistols - no Glocks - and for a 9mm carbine. I reload a variety of bullet styles and weights. I don't have much problem with chambering. Is this undersized die really intended to ensure that the round will go into battery in typically more finicky chambers? That's the sense I get from what I've found online. Would it tend to improve accuracy by making neck tension more uniform? At least, for whatever that's worth for a 9mm pistol...
C
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I agree with sp01 Shadow.
My "regular"9mm Lee sizing die does this. Some say the FCD does this, but that's just not so with mine.
After seating the fmj .355 bullet with or without taper crimp and without the FCD, mine have this distinct coke bottle shape and good neck tension .
Added: aliber and "regular size"
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The best thing about under sizing is neck tension and the ledge formed just behind the bullet to stop a possible setback. A lot of people complain about the "Coke Bottle" effect but I demand it. If a sizing die does not bring the case down small enough so I cannot see the base of the bullet in the case after seating, it goes directly in the green box. It may not look sexy but I am reasonably assured that I have good neck tension and a large enough self made cannelure that the bullet is not going to back up in the case on feeding.
Same here.
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I first obtained a "U-Die" when shooting .45 and picking up range brass for reloading. Some of the range brass would not chamber after loading. A buddy told me that the brass that would not load had probably been fired through a Glock which has loose chamber dimensions allowing the brass to expand too much. If you only reload your own brass and not range pick-ups, you may not need U-Dies.
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The point being made was about adding neck tension and prevention of bullet set-back, not bad cases.
I believe the biggest Glock unsupported chamber problem was 40 cal. and several generations back. (https://www.reddit.com/r/reloading/comments/2n4hy4/what_glock_bulge/)
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I agree with SP01. Standard dies have done fine for me in 9mm so far. I did have problems in 45 auto with adequate bullet tension with a Hornady sizer. It was ok with most brass but thinner wall brass wouldn't be sized down enough for a tight bullet fit. I went with a Redding dual carbide which really sizes down the upper portion of a case so that even the thinnest brass (Starline 45 auto rim) has good tension and a nice coke bottle look.
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I did have problems in 45 auto with adequate bullet tension with a Hornady sizer. It was ok with most brass but thinner wall brass wouldn't be sized down enough for a tight bullet fit. I went with a Redding dual carbide which really sizes down the upper portion of a case so that even the thinnest brass (Starline 45 auto rim) has good tension and a nice coke bottle look.
That sounds like an expander issue, not a sizing die issue.
;)
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I use the EGW (made by Lee) undersized dies on 9 mm, 40 s&w and 45 acp. Would never go back to standard dies.
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The point being made was about adding neck tension and prevention of bullet set-back, not bad cases.
I believe the biggest Glock unsupported chamber problem was 40 cal. and several generations back. (https://www.reddit.com/r/reloading/comments/2n4hy4/what_glock_bulge/)
You may want to reread the OP's original post if you are responding to my post...
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Some may say to not work the brass more than necessary. I try not to "bell" the neck, only enough to consistently seat a bullet with out damage or changing its size. 9mm is cheap and plentiful, not to worry about wearing out my supply.
My completed rounds often look slightly hourglass shaped. "Normal" Lee sizing die. This reduces bullet setback without over crimping. I never had any problems with used brass or discovered any particular reason to size smaller than what my dies already do. Again, 9mm is plentiful enough, either free or cheap enough to not hesitate to throw an undesirable headstamp or questionable case in the recycle bucket. I certainly would not spend time or money to "repair" a 9mm case.
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Absolutely in agreement with vwpieces findings.
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Thank you for the info. I use used the Dillon resizing die, never had an issue. I was just curious what everyone's opinion on this was.
C
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I use a Lee U die mostly on mixed 40 range brass (when my brass is mixed with folks nearby) to protect against Glocked brass... so far, so good
I have and have used the dies on 9 mm, but have had fairly clean brass
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Never heard of U dies for 9mm.
I use one for .45 Auto.
All my brass is Remington, which is a bit thinner.
Sizing with the U die gives more consistent neck tension.