Wilson seater with micrometer top causing bullet run-out?

[LongRanger]

If you are getting poor run-out when seating bullets in cases with virtually “perfect” necks while using your Wilson seater with the micrometer top, the culprit could be that the seater stem is cocking the bullet to one side.

I have 3 different Wilson seaters with Sinclair micrometer tops and the stems on all three are a loose fit in the die. The “wiggle” can be felt when the micrometer set screw is loose. When the micrometer’s set screw is tightened, it pushes the stem to one side. The result can be easily seen if you hold the die up to a good light source and sight between the top of the die and bottom of the micrometer top. You will see light between the die and top. The top will bear on one spot on the die, and the contact point will move around the die top as the micrometer top is turned. As the top turns, you can see the little sliver of light between the die and top move also.

If the set screw is backed out until it does not touch the stem, the micrometer top fits perfectly flush (but not necessarily square) on the die body. By leaving the screw loose, the stem is free to find a home on the ogive and I get better results. Of course, this means that attention must be paid to keep the micrometer at the desired setting.

It is very important that the bullet be in square contact with the case mouth before trying to seat. This is best done by first putting the case into the die, putting the bullet down the bore, and then putting the micrometer top onto the die. A square mouth with a really good, even, polished chamfer is essential. Wilson would say that this method could cause undue wear on the stem over time, but I think the already sloppy fit of the stem eliminates this concern.

I seat by lowering the arbor press handle until the ram touches the top, give the top 3-4 gentle taps to start the seating, then carefully rotate the top 180 degrees, give a couple more taps then fully seat the bullet.

Frank B.

 

[lrgoodger]

I had the issue you describe on my 6BR Wilson stainless seater. I was able to put enough pressure on the stem to straighten it so that the top surfaces fit together flush. It was not affecting runout, but it was causing slightly inconsistent bullet seating depth (less than a thou). Squaring it up solved the problem.

 

[brian427cobra]

Frank, I too use the Sinclair tops on my 260 and 308 Wilson dies, question is wouldn't the tight fit of the stem in the die negate the pressure the set screw is putting on the stem.

 

[ni man]

I am having the problem of inconsistent bullet seating with my Wilson seater die , when I measure my over all length it is changing by about 2 thou . I had trimmed the meplats so they must be seating square" I thought " really annoying .Will take a better look at the die its self .
I have a lyman turret press should I really be using a single press for 6mmbr

any other ideas whats wrong your thoughts appreciated

northern Ireland man
(ni man )

 

[Leaddog]

Frank - I use a Wilson Mic Top Seater and it is the most accurate Seater I have for my Dasher. It is the mic top conversion. Not the dedicated micrometer Seater. My runout is zero. Yes, zero.

I do not drop a bullet down the Seater bore. I place a bullet on top of the case and lower the Seater body. Seating is done by one smooth move of the arbor. No taps, no rotations. Have you checked the concentricity of your necks before seating?

I use a Redding S FL die with the carbide expander. I resize once fully, rotate the case 180 degrees and do it again. My necks are also turned.

The loaded ammo is perfect and I don't see the problem you mention with the stem.

 

[Leaddog]

I am having the problem of inconsistent bullet seating with my Wilson seater die , when I measure my over all length it is changing by about 2 thou . I had trimmed the meplats so they must be seating square" I thought " really annoying .Will take a better look at the die its self .
I have a lyman turret press should I really be using a single press for 6mmbr

any other ideas whats wrong your thoughts appreciated

northern Ireland man
(ni man )


Seaters don't index off the meplats. They contact the bullet just north of the ogive. Sort your loaded rounds by measuring cartridge base to ogive for consistency.

 

[ni man]

your answer .
Seaters don't index off the meplats. They contact the bullet just north of the ogive. Sort your loaded rounds by measuring cartridge base to ogive for consistency

That would explain things I could not work it out and was wrongly adjusting my die to get the right oal
I will leave alone in future . I am sure I was not the only person did not know the seater contacted just north of ogive
thank you thank you thank you

ni man

 

[rayporter]

if your bullet does touch the bottom of the seater stem you will have a worse problem. the stem will need to be drilled deeper.