Sizing to a Specified Size

[Farmall 1066]

Anyone else have sizing dies that don't size as specified?

I have some Lyman's that do (or don't). Marked .429, sizes .4275-.428. A 452 that sizes .451. A buddy has a Star that is supposed to size .452, but averages .4505!

Do you think hardness of the bullet, or manufacturing tolerances are to blame?

I have had undersized Lee's too, but they are easily fixed by lapping. I'm afraid I'll create a mess if'n I try this with the Lyman's!

Anyone else have this trouble? I have verified these measurements with 2 micrometers and a Brown & Sharpe digital caliper. All QC verified, to make sure I'm not going nuts(er)!

Andy

[runfiverun]

what size do the boolits come out of these sizers measure?
i cast and size in one of my 452 star sizers the same day, so that the soft 454 boolits will measure 453 when i am done.
there is some springback to some alloys.
i have also seen some sizers get build up of lead in them and measure undersized when they aren't.
if you want to make them a bit bigger.
take out the rod that lifts them up,so you have a pass through sizer put some lapping compound on about 6 boolits and pass them through then run a regular boolit through and measure it.
continue till you are happy.

[Farmall 1066]

The second set of numbers is the actual size of bullets passed through them. The .429 sizes .4275-.428", and the 452 sizes bullets at .451"

They arent leaded at all, and the bullets don't seem to spring back at all! My .459, .358, .359 and .357 Lyman dies all size as marked. So do the .309, ..311 and .314. At least I think the .314 would, if I could get Lyman to make a 314299 mold that'll cast to that diameter!
Not much luck there so far!
Andy

[mooman76]

I have a Lyman .430 that does .431, but no complaints there!

[ANeat]

Most companies base the size off of a standard alloy, 92/6/2 probably. A softer alloy will spring back less and come out smaller than spec. A harder alloy will spring back more and be larger than spec.

In most cases that would be my first guess. If its several thou off then it may be off a little plus the alloy.
Try casting a few from lino and see what size they come out at.

[lathesmith]

This is a subject that comes up frequently when ordering sizer dies, I have been thinking of starting a new thread to address this very subject.
Several factors can influence final sized dimensions, with alloy hardness and bullet size before sizing being two of the most critical. Bullet shape and amount of bore contact are also factors.
Please read the Lyman Cast Bullet Handbook, pages 53-64, with special attention being paid to the chart on page 58. Sizing dies are generally made to get closer to size for the harder alloys; if your alloy runs softer, or you are using some special hardening or heat-treating process, expect some variation mostly to the smaller side.
lathesmith

[montana_charlie]

Sizing dies are generally made to get closer to size for the harder alloys; if your alloy runs softer, or you are using some special hardening or heat-treating process, expect some variation mostly to the smaller side.

I concurr...
My Lyman 459 die sizes 'soft lead' to 0.458", and my 458 sizes down to 0.457".
If I were using Lyman #2 alloy, I expect they would come out at the 'claimed' diameter.
CM

[cbrick]

Alloy is the culprit here. Increasing anitmony will increase the final sized diameter. It's not the die makers fault, any change in alloy will result in a change in final sized diameter.

Bullet alloy as-cast & final dia. sized (.308 sizing die)

---------------Lead-------Wheel Weights-----Lyman #2----Linotype
As-cast dia.--.309"----------.3095"-----------.310"---------.3104"
Sized dia.----.3078"---------.3079"-----------.3084"-------.3084"

Larger diameter bullets give larger results. Example, this .308" was .0001" smaller sized diameter with WW in this example but the same alloy in a 45 cal bullet would size to around .4518" from a .453" die and a 22 caliber bullet would be only a few tenths under actual die diameter.

The chart is from my web site and if I remember correctly it's from the NRA Cast Bullet book.

Rick

[Buckshot]

..............In my blurb I send folks inquiring about Lyman-RCBS and Lee push though dies, I state I use WW alloy to 'proof' them, and then include the slug with the die when I ship them. WW serves for probably 90% of the cast shooting being done. However I add that if the die is for very soft or hard lead, they need to send me 3 slugs to proof their die. They get exactly what they want that way.

...............Buckshot