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Overseating Issues with 40 S/W


kmc

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I recently have been experiencing an "overseating" of bullets into .40 brass. I've reloaded 10s of thousands of rounds but never seen this prior--I'm hoping someone will have an idea. I'm using range brass, Hornady One Shot, 180gr Blue Bullets and reloading on a 650--have been using this combination without change the past two seasons. For reasons I won't get into here, I recently changed out my sizing die (for a Mighty Armory) and my seating die (for a Redding Competition seating die). Prior to that time, I was using all Dillon dies, though I've been known to occasionally use Lee dies. Everything seemed fine after the change and I cranked out 600 rounds without issue. This week, I found 2 rounds out of a 100 where the bullet had seated much deeper than it should. One of the cases was cracked and I blamed the overseating on that and continued. However, in the next hundred I again found two rounds that were overseated. It almost seemed as if there wasn't enough case tension to hold the bullet properly. The powder funnel is not excessively belling the case and the bullet is only overseated after the seating station is complete. I removed and reinstalled the sizing, seating, and crimping dies but didn't notice anything unusual about them. Continuing, I again had bullets seated too deep in two rounds and I tried running each back through the press again using different bullets and both ended up overseating again! I finally got out the micrometer and learned that most brass was .423ish prior to sizing, .417ish after sizing, and .421ish with a finished load. The bullets were consistently 0.399. On one of the brass that loaded overseated, I noticed it was 0.424 AFTER sizing.

For now, I removed my fancy Mighty Armory sizing die and switched back to the Dillon. Nothing wrong so far in the first 200... Thoughts on what might be going on?

First picture shows two overly seated rounds in front with correct one in rear. Second picture shows correctly seated round in crimping station and bullet seated too deeply in the seating station (after seating and crimping.).

IMG_6992.jpg

IMG_6985.jpg

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common issue that's bc your brass has been fired too many times and it's stretched out larger than normal. case wall thickness is thinned out. Those bullets are .400 so they will slide right in. that's one reason why I never buy .400 diameter bullets

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The more a case is reloaded the harder the brass becomes and springs back more after sizing. The Lee under size die will size the case .002 to .003 smaller in diameter to compensate for brass spring back. And if using range pickup brass the Lee and EGW undersize dies are added insurance to prevent bullet setback.

 

Below a 9mm cartridge resized with a Lee undersize die, the case is wasp waisted and showing the increased bullet grip.

 

MfcwIQB.jpg

 

 

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These arguments do make sense but what doesn’t jive I have is I’ve loaded well north of 10k with this bullet and range brass the last two years. I don’t recall having setback issues at any point during this time until now. I’ve now seen ~9 over the last 600 rounds. Seems like there must be another factor too. I’ll use my Dillon die for a few hundred more rounds and see what I find. I think I’ve got a U-die around here somewhere and can try that too.

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Maybe your just running into some brass that’s been loaded to much and if it range brass no idea of how much it’s been reloaded before. I use a ma size die and I have no issues. I switch back and forth sometimes just to use the dillon sizer and no issues. I would chalk it up to fatigued brass. I personally didn’t like the Redding micro seater. I also use 180 blue bullets. My line up is dillon size, seater, crimp. Alpha or mbf funnel and mighty armory sizing die most of the time for my competition rounds. Only time I’ve seen this in my setup is with worn out brass and it was like yours not many per 1000. Now since I have my own private range I can sort the brass by how many times I’ve personally loaded it. 

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6 hours ago, Furrly said:

Get Rid of the MA die!! period 

Can you tell me more? It came highly recommended from a guy running an automated setup (in 9).

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6 hours ago, Guy Neill said:

Were the cases all of the same make (headstamp), or mixed?

 

Did you look at case wall thickness?

 

Have you measured a sampling of the bullets to look for variations in diameter?

 

 

Always has been mixed.

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46 minutes ago, Dirtchevy841 said:

Maybe your just running into some brass that’s been loaded to much and if it range brass no idea of how much it’s been reloaded before. I use a ma size die and I have no issues. I switch back and forth sometimes just to use the dillon sizer and no issues. I would chalk it up to fatigued brass. I personally didn’t like the Redding micro seater. I also use 180 blue bullets. My line up is dillon size, seater, crimp. Alpha or mbf funnel and mighty armory sizing die most of the time for my competition rounds. Only time I’ve seen this in my setup is with worn out brass and it was like yours not many per 1000. Now since I have my own private range I can sort the brass by how many times I’ve personally loaded it. 

I’ll make a few hundred rounds with the Dillon sizer and Redding seater. If I get more of the same, next swap out will be Redding die.

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Get your self a mighty armory sizing die. they are expensive but worth every dollar. It Sizes the case farther then a lee U die.  It’s hard to tell in the pic, but it leaves 1/16th unsized on the bottom of the case. But if you roll size or bulge bust that takes care of that area anyhow.

image.jpg

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1 hour ago, CZGeoege said:

Get your self a mighty armory sizing die. they are expensive but worth every dollar. It Sizes the case farther then a lee U die.  It’s hard to tell in the pic, but it leaves 1/16th unsized on the bottom of the case. But if you roll size or bulge bust that takes care of that area anyhow.

image.jpg

Uh, did you read my original post and the problem I now have? One of the two changes I made was moving to a MA sizing die.

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you have a size issue. weather its under sized bullets, thin brass or a sizing die you will have to determine.

by your measurements your bullets are .001 undersize but that could be your calipers tolerance. you have used these

in the past with no issues.Next you changed to a MA sizing die this is where I believe your problem lies. This die REQUIRES

that you actually crimp not just remove the bell. go back change one thing at a time starting as you already said back to the

Redding sizing die. Then you could try the seating die you used in the past if you still have issues. extremely thin cases could be an issue

but I have not encountered any .   If every thing is back as you started and still have issues then it could be the bullets.

Edited by AHI
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8 hours ago, kmc said:

I’ll make a few hundred rounds with the Dillon sizer and Redding seater. If I get more of the same, next swap out will be Redding die.

This 👆

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MA dies have been know to have out of spec issues.. I myself have ran into those problems.. They are great dies when they are right.. For the sake of process of elimination I would go back to his original set up and start there.. The Redding seating die should not be a problem however if the internal spring is binded or bent there can be a setting problem. 

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3 hours ago, Furrly said:

MA dies have been know to have out of spec issues.. I myself have ran into those problems.. They are great dies when they are right.. For the sake of process of elimination I would go back to his original set up and start there.. The Redding seating die should not be a problem however if the internal spring is binded or bent there can be a setting problem. 

Any idea on how many times this has happened? I’ve had mine for a few weeks and it’s really nice. Just wondering if I got lucky or if it was just a fluke with the out of spec MA dies.

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2 hours ago, CZGeoege said:

Any idea on how many times this has happened? I’ve had mine for a few weeks and it’s really nice. Just wondering if I got lucky or if it was just a fluke with the out of spec MA dies.

There initial offerings of there dies had issues, there version 2, which you should have, appears to have worked out the kinks doesn't mean some don't fall through the cracks. If yours has been working then don't worry.. Kmc may have an issue with his due, that's why I suggested he go back to his original set up.. Process of elimination 

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5 hours ago, Furrly said:

There initial offerings of there dies had issues, there version 2,

Is there a way to distinguish which version I have?

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