when sizing

[white eagle]

lnfp or cast boolits with no shoulder there are times when some of the boolits get sized more on one side than the other and look lop sided or off center.Are these in fact off center or not concentric and will this affect their flight characteristics?

[Mk42gunner]

My opinion: If a boolit looks lop sided, or sized off center, it probably is, and gets tossed into the cull pile to get remelted. Why even load a projectile that you think is not the best you can make?

Robert

[DLCTEX]

That is often caused by using a poorly fitting nose punch IMHE.

[gray wolf]

Sometimes I have found that bullets of the LBT design with no visible front band will do this.
Especially if they are sized a little to much. the lead is pushed up from the bottom using a Lyman type sizer.
It can be exaggerated if the bullet is a little out of round.
I think Tom at accurate molds mentions this and that's why he favors a very slight hint of a front band.
It's early and I just got so so maybe someone can clean up my explanation.

[milrifle]

My brand new Lyman 4500 sizes off center. I sent it back to them minus the set screw that holds the top punch in, because I had been trying to allow the top punch to 'float'. I guess that was all they needed to assume I didn't know what I was talking about and sent it right back to me with a new set screw and told me to use it. Pissed me off! It sizes WAY off center. To get it to work, I have to chuck the top punch up in the lathe and turn the shank down several 1000ths so it can sit off centered in the top ram. I hold it in place with some bullet lube. Seems to work, but it is a shame a brand new piece of supposedly precision equipment has to be modified in such a way just to make it work.

[montana_charlie]

To get it to work, I have to chuck the top punch up in the lathe and turn the shank down several 1000ths so it can sit off centered in the top ram. I hold it in place with some bullet lube. Seems to work, but it is a shame a brand new piece of supposedly precision equipment has to be modified in such a way just to make it work.
If it is only 'a few thousandths', maybe there is paint in the hole for the top punch which keeps the punch 'a few thousandths' of an inch too close to the front.

CM

[cbrick]

It's the nature of the beast of in & out sizers. I did a comparison of RCBS, SAECO & Star sizers on a machine shop comparator and the difference in concentricity was amazing. Yes, this off center sizing will dramatically effect accuracy and of course the longer the range & higher the velocity the more effect it has. Straight thru sizing with a flat punch on a flat boolit base only for me.

Rick

[dtknowles]

If you put a little shoulder on the bullet, ie. a leading band it will cover up the fact that the bullets are sized off center so they will look nice but they will still be off center.

With the bullets where the ogive fairs into the bearing surface you can clearly see when a bullet is sized off center. While I can never get them to be perfect, I work hard with the top punch to get the as good as possible and then scrap the bullets that fail my arbitrary standard. I have carefully sized down bullets as little as 0.001 and still the witness marks on the ogive are not perfectly parallel to the base and grooves. Since the die sized the bullet around the whole 360 degrees and only made the bullet 0.001 smaller the amount of off center must be very small but it still bothers me. I wonder when the bullet starts up the throat and lead that it will contact first on one side and then harder on that side causing the bullet to not launch straight into the rifling. Maybe with a leading band, even if sized a little off center it would launch straighter since the nose of the bullet would be in the rifling and the leading band would hit the throat and lead square.

Tim

[cbrick]

I wonder when the bullet starts up the throat and lead that it will contact first on one side and then harder on that side causing the bullet to not launch straight into the rifling.

That is true and the same with revolvers when contacting the forcing cone.


Maybe with a leading band, even if sized a little off center it would launch straighter since the nose of the bullet would be in the rifling and the leading band would hit the throat and lead square. Tim

It would still off center, not concentric. Worse yet once the boolit clears the muzzle and is in free flight it is still not concentric, IE out of balance, heavier on one side than the other. The more of course the sizing is off center the worse the accuracy.

As with most things with cast boolits the shorter the range and lower the velocity the less effect. The longer the range and the higher the velocity the more effect it has.

Rick

[montana_charlie]

If you put a little shoulder on the bullet, ie. a leading band it will cover up the fact that the bullets are sized off center so they will look nice but they will still be off center.

With the bullets where the ogive fairs into the bearing surface you can clearly see when a bullet is sized off center.

I wonder when the bullet starts up the throat and lead that it will contact first on one side and then harder on that side causing the bullet to not launch straight into the rifling. Maybe with a leading band, even if sized a little off center it would launch straighter since the nose of the bullet would be in the rifling and the leading band would hit the throat and lead square.

Tim
For all of the reasons you mentioned ... it really IS worthwhile to pay the money for a custom mould if you can't find one that produces a bullet you can use 'as cast'.
I have a Lyman 45 lubrisizer, but I only use it to apply lube.
I don't size any of the bullets I use.

CM

[white eagle]

So then what is the most accurate way to size ??
A Lee push through??

[cbrick]

Yep, either the LEE push through or the Star Lubrisizer. A flat punch on a flat boolit base will produce the most concentric boolit.

Rick

[44man]

I hate a lube-sizer even if I don't actually size, just lube. I use Lee dies 99% of the time.
My old RCBS was sizing off center, found the ram and hole was worn or maybe made too loose. I drilled and tapped in 3 places to put brass screws around the boss so I could adjust the ram position and it works.

[Reg]

Used to use a Lyman 45 for years and noticed that sometimes the same bullet would size off center then the next time it wouldn't. It was never much, sometimes so little you really look hard to see it but if a bullet looks off center to any degree, it is.
Made up a push thru type sizer to see how well the system worked and had no more off centers. None !!
This is about the time I was changing my whole approach to using cast bullets and how I made them. Now, I only use my homemade push thru die or Lee dies, sold the old 45 and have gone to pan lubing with various home made lubes and tumble lube with 45-45-10.
End result ? Groups have shrunk to less than half what they used to be. Leading is no more. Best of all, now, when I show someone a bullet I have made, it looks great and I know it will shoot great.