Inconsistent concentricity

joelkdouglas · Dec 12, 2018

kraky1":25ehzlpk said:
I will throw out what I believe to be the culprit in your seating process...at least a good chance. I have a feeling that the seating stem in your die is not a match to that profile of that bullet. I would check very closely and see if the tip of the bullet is bottoming in the seating stem before the cup is contacting the outside of the bullet. If that is what is happening there is no seating die in the world that will keep you from getting random goofy run out. I have had this happen in several different calibers with different brands of dies the bottom line is when you go to a really Sleek profile bullet sometimes the push from the seating die is right at the tip of the bullet and that will cause it to go off- line pretty easily.

Thanks for your post, I’m going to check one of my bullets vs stem and see what there is to see! Makes complete sense.

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thatguySHM · Dec 12, 2018

I did check that quite early on. From my experience, newer quality dies are made for the increased bullet length past the ogive making it more difficult to seat off the tips.

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Finaddictions · Dec 15, 2018

I’ve experienced almost exactly what you’re going through, and it came down to using a VLD chamfering tool and doing more than just “touching” the case. When I put a good smooth chanmfer on the case mouth my concentricity got very consistent.

ElmerThud · Dec 16, 2018

Finaddictions":2wsowpr9 said:
I’ve experienced almost exactly what you’re going through, and it came down to using a VLD chamfering tool and doing more than just “touching” the case. When I put a good smooth chanmfer on the case mouth my concentricity got very consistent.

A very desireable addition the VLD chamfer tool, . .. helps considerably.

truck driver · Dec 16, 2018

This has been a very interesting and informative post.
I must admit I'm as dumb as a box of rocks concerning a lot of reloading techniques that have been discussed and used on this forum.
I mostly use Redding dies and buy the Micro seater stem separately.
The last set was for my 300 Win and when buying the stem I opted for the VLD model just in case I wanted to try the bullet.
I could never get the stem to stay tight in any of my seating dies so I got an O-ring that would tightly slide over the stem and fit in the groove, when the stem is screwed into the die and tightened the O-ring provides enough friction to hold the stem snug and cushion the bullet when seating.
Does it help with concentricity I don't know but it sure helps to keep the stem from coming loose and screwing out when adjusting seating depth.
I also use the O-ring under the sizing die to stop spring back when sizing brass.
I think this has a lot to do with consistent loads or at least it has helped me.
One trick I learned here and one I found on the Bench Rest forum.