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 Seating die causing ring around the plated bullet
blake-b  [Team Member]
1/4/2009 8:48:59 AM
I could have sworn I saw a thread about this a while back but couldn't find it after much searching.

I'm using a Dillon 550B with Dillon .40 die set with 180 gr bullets. The seating die is creating a ring around the bullet during the seating process, it's not going through the plating, just indenting a circle. If I back the die out I don't get the bullet seated deep enough but the ring disappears. I've never had this problem before.

While trying to figure this out, I also noticed the bullets are bulging the top part (1/3) of the case almost as if the bullets are just a little too big for the casing. I will try and get a picture but the best way to describe it if you have seen the bulge at the bottom of casing known as the glock bulge, it's the same thing but at the top like the bullet is stretching the casing slightly around itself. As I type this, I realize I should have measured the bullets to see exactly how big they are.

What would cause these two things?

ETA: Just read on dillonprecision.com that the bulge is normal as long as it goes all the way around the casing, which mine do, and the round chambers.
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ebrm4  [Member]
1/4/2009 9:03:56 AM
I don't know about Dillon, but when RCBS seating plugs do that, if you send them the seater plug & a bullet or two you are using, they will fix it for you. For free! Call Dillon, I guess they will do the same.
xdmikey  [Team Member]
1/4/2009 9:22:50 AM
I get that as well. The bullet doesn't mind & the barrel doesn't mind & the target doesn't mind so why should I mind?
It's been so long I saw that that I forgot about it.
DanaHillen  [Member]
1/4/2009 10:13:33 AM
"The seating die is creating a ring around the bullet during the seating process, it's not going through the plating, just indenting a circle. If I back the die out I don't get the bullet seated deep enough but the ring disappears."

I've cured this in .45 ACP (using semi-wad cutter bullets) by SHORTENING the seating end a bit so that the bullet goes in the opening far enough to hit the inside BOTTOM of the seater and does not contact the circumference of the bullet.
You might take a look and see if this might work for you....
Dana
NA_Wreckdiver  [Team Member]
1/4/2009 10:53:24 AM
Originally Posted By blake-b:

I'm using a Dillon 550B with Dillon .40 die set with 180 gr bullets. The seating die is creating a ring around the bullet during the seating process, it's not going through the plating, just indenting a circle. If I back the die out I don't get the bullet seated deep enough but the ring disappears. I've never had this problem before.




I am NOT familiar with Dillon dies... but assuming they work like every other die (RCBS, Hornady, etc)
then based on you description, then this is what I am fairly sure is happening.

You probably have a "roll crimp die"... the die is screwed down to far & is over crimping an uncannalured
bullet... thus creating the ring in the bullet & bulging the case. Take a new round (factory), back the seater plug
up into the die, screw the die down onto the loaded round just until you feel it touch the brass. Then screw the
seater plug down until it hits the bullet. This will get you VERY close. You will have to fine adjust for your loads.
918v  [Team Member]
1/4/2009 12:46:56 PM
No manufacturer makes a .40 S&W seater die with a roll crimp feature. They all taper crimp.

Plated bullets have a soft core and a thin jacket. If case tension is high, the bullet is hard to seat and the seater plug molests the bullet.

I will parrot the suggestion of indexing off the flat bottom of the seater plug. That way the sides of the seater plug will not exert any force against the bullet nose.
ARinKCMO  [Team Member]
1/4/2009 12:48:53 PM
I'm in the camp of 'this is normal, don't worry about it'. Especially on thin plated bullets like Rainers and berrys, the 'ring' is completely normal.
COSteve  [Team Member]
1/4/2009 1:11:10 PM
While the finished case bulge sounds normal, if you haven't had this problem before. I'd suggest a few easy things to try before you start grinding on your dies:

1st - Clean your die set with brake cleaner. Over time they can get dirty and maybe that is leaving a ring round the seating die which transfers to the bullet.

2nd - If you are seating and crimping with a single die, back the die body out just a bit and screw in the seater a bit. It could be that you are starting your crimp early and that is making the bullet harder to seat.

3rd - Try belling the case mount just a tad bit more.
rg1  [Member]
1/4/2009 1:15:34 PM
You can help this a little by polishing the seater stem that contacts the bullet. Remove any sharp edges. You can use a bullet as a guide and by placing a flexible piece of fine sandpaper over the bullet and twisting it against the seater stem. Some die makers make a seating stem for a particular bullet and will do that for you if you send them sample bullets and your stem or call and ask for a stem for a particular bullet.
You can help the stem a lot by just polishing and removing sharp edges.
callgood  [Team Member]
1/4/2009 5:28:43 PM
Did Dillon send another seating stem? With some calibers on the Square Deal they include multiple stems for different type bullets. Look in your kit and see if this is so.

I am also in the "What, me worry?" camp.
tenmikemike  [Member]
1/9/2009 12:02:06 AM
Originally Posted By blake-b:
I could have sworn I saw a thread about this a while back but couldn't find it after much searching.

I'm using a Dillon 550B with Dillon .40 die set with 180 gr bullets. The seating die is creating a ring around the bullet during the seating process, it's not going through the plating, just indenting a circle. If I back the die out I don't get the bullet seated deep enough but the ring disappears. I've never had this problem before.

While trying to figure this out, I also noticed the bullets are bulging the top part (1/3) of the case almost as if the bullets are just a little too big for the casing. I will try and get a picture but the best way to describe it if you have seen the bulge at the bottom of casing known as the glock bulge, it's the same thing but at the top like the bullet is stretching the casing slightly around itself. As I type this, I realize I should have measured the bullets to see exactly how big they are.

What would cause these two things?

ETA: Just read on dillonprecision.com that the bulge is normal as long as it goes all the way around the casing, which mine do, and the round chambers.


Yeah, you got two bullet seating plugs (at least with RCBS you do). One is for round nose bullets, the other is for flat point. Using the RN to seat FP bullets will leave a ring in the jacket.

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