Lyman question

[Sixgun]

I have been useing this Lyman mold for several years.  When I first got it I just plinked with the bullets with a 4 inch revolver and never worried too much about accuracy.  I figured if I hit someting once in awhile, I was ok.  

Well, now I am shooting Cowboy Silhouette and got out all of my .358 molds and started getting serious.  First thing I noticed was that the bullets from my Lyman mold shoot a shotgun pattern at 50 yards.  By the way, it is a 2 cavity, 150gr Keith style SWC.  The bullets that I cast from this mold look good so I decided to weigh them.  I found that I have two different weghts of bullets from this mold.  Out of 160 bullets I have two distinct weights of bullets.  One group of 80 weighs 152gr + - .7 gr and the other group of 80 weighs 150gr + 0 .5 gr.  They shoot different too.

I have two Lee molds also.  A 166 gr SWC and a 148gr WC, both two cavity molds.  From both of them all of the bullets weigh in at a + - .3gr.  

Are Lyman molds really that bad or do I just have a bad one?  Also, are the cheap Lee molds really that good, or do I have a pair of really good examples?

The groups from the Lee molds are pretty good also.  The 166 gr mold will group under 2 inches at 100 yards, all day.  The 148 WCs group under 2 inches at 50 yards but at 100 yards are all over the paper.  I know 2 inches is not real good but this is done with 55 year old eyes and metalic sights.  I don't expect my groups to be any smaller on the target than my front sight covers up on the target.

If you have any thoughts or experience on these things I would like to hear them

Thanks, Sixgun

[Leftoverdj]

I would not expect a three grain variation in bullet weight to result in "shotgun patterns". Undersized bullets will, so your next step is to measure your bullets.

Lyman has been in business a lot of years and some of those years have been better than others. Some moulds have come out their their doors that were cut by cherries that had been sharpened one time too often. Sometimes they even did it on purpose. Check your mould to see if there is a "U" stamped at the end of the model number. That would stand for "undersized".

You have your bullets weighed and sorted by cavity. I'd try them to see if the segregated bullets would group. An oldtimers trick is to file a small notch into the nose of one cavity. This produces a little flashing so that bullets from that cavity can be visually identified without weighing. You just flick the flashing off with your thumbnail as you size.

You can also just go with what you've got. There ain't a lot of room for improvement over the groups you are getting with 166 grain. Two inch groups at 100 yards with cast bullets and an iron sighted carbine are cause for celebration. Treat that mould tenderly, though, because Lee does not list it any more.

The only other thing I can think of is for you to do some swapping with the fellows on this forum to find  bullets that work for you. Once you've found one that works you can buy that mould.