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Dillon .38/.357 Seating Die Crimping Case Mouth = Coated Bullet Shaving


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Well,

My first thought

Clean the die out. The seater could be full of crud!

Set the bell to allow you to set a bullet on it.

Back off the seater die stem out and raise the belled round and bullet into the die and then

start lowering the seating stem till you start to seat the die.  Refine the COAL till you

have it right.

 

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I might not be as stupid as I first thought (or maybe just half as stupid). My Dillon seating die (not a combo die) definitely de-flares the casemouth when I flare too much. You can hear the casemouth scraping against the sidewalls of the die before the bullet gets seated. e.g. Test cases flared to .3885 and .3930 got de-flared to .3825, which seemed like the maximum flare the die would accept. ddc's comment lit the little light bulb in my pea-brain. Since the bullets mic at .358 this shouldn't be a problem? So I flared to .3875, but the bullets still got shaved. Why? Well, I think the real issue is that the sizing die does its job too well! The sizing is so aggressive that it looks like the base and sides of the bullets are getting shaved when they're being seated. This, along with the seating die de-flaring the casemouth while simultaneously seating the bullet can't be a good thing. I'm using a MBF powder funnel, so the bullets are centred. I could try a different sizing and or seating die(s) but I think it's cheaper to just give up on the coated bullets and go back to plated bullets.

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1 hour ago, 4n2t0 said:

I might not be as stupid as I first thought (or maybe just half as stupid). My Dillon seating die (not a combo die) definitely de-flares the casemouth when I flare too much. You can hear the casemouth scraping against the sidewalls of the die before the bullet gets seated. e.g. Test cases flared to .3885 and .3930 got de-flared to .3825, which seemed like the maximum flare the die would accept. ddc's comment lit the little light bulb in my pea-brain. Since the bullets mic at .358 this shouldn't be a problem? So I flared to .3875, but the bullets still got shaved. Why? Well, I think the real issue is that the sizing die does its job too well! The sizing is so aggressive that it looks like the base and sides of the bullets are getting shaved when they're being seated. This, along with the seating die de-flaring the casemouth while simultaneously seating the bullet can't be a good thing. I'm using a MBF powder funnel, so the bullets are centred. I could try a different sizing and or seating die(s) but I think it's cheaper to just give up on the coated bullets and go back to plated bullets.

 

The symptoms you are seeing are similar to those that are experienced when people have problems setting up a combo seating/crimping die. That's just an FYI as much as anything... 🙂

 

One thing I'm noticing is that your flare measurements are far in excess of any that I typically see mentioned.

 

I have not done a lot of loading with coated bullets so maybe I'm out of the loop but my recollection is that a flare of .385 is more than I ever needed.

 

For jacketed I'm down around .381/.382.

 

To me a flare of .3930 seems way way big but maybe there is something about coated bullets that I'm not up to speed with.

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@4n2t0:

 

@ddc has given you some great advise.  IMO, if I was loading coated bullets sized at .358", I would swap out my MBF powder funnel for one of these .358 funnels and try again!

 

https://www.photoescapeinc.com/products/9htc-ptu.html

 

And definitely reduce your flare which shouldn't be needed with the correct funnel.

 

HTHS!

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Thanks, I'll take a look at the funnel. It looks exactly like the MBF funnel but I guess with a larger diameter?

 

Just to clear one thing up, I don't flare to those measurements. It was a test to see what the seating die was doing to the casemouth. Now I know that .3825 is the internal diameter of that seating die.

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I had loaded alot of 40's on lee dies, but decided I needed to upgrade and bought a Dillon set.. End result was a seat die thrown in the swamp.. I never could get it to work correctly. I would get failure occassional failure to chamber which would dang near lock up gun.  Best I could tell is it was somehow deflaring and grabbing the bullet before it was fully seated and causing a slight flare.. And this was suppossed to be a seat only die but I dont think it is,,, I backed it out lowered stem,, yadda yadda,, and still had issues with my ammo.. I finally chucked it and put the Lee back in and problem stopped

 

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35 minutes ago, 4n2t0 said:

Thanks, I'll take a look at the funnel. It looks exactly like the MBF funnel but I guess with a larger diameter?

 

Just to clear one thing up, I don't flare to those measurements. It was a test to see what the seating die was doing to the casemouth. Now I know that .3825 is the internal diameter of that seating die.

I think as @Joe4ddid in his post above, you may want to look into trying another seating die.

 

With a .358 bullet, and if your case wall thickness averages .012", then you'll end up with an OD of the round after the bullet is seated of ~0.382".

 

Something to think about.........

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