RCBS oversize, now undersize

[Irascible]

I like RCBS moulds. Good quality, BUT I wish their sizes were more accurate. I posted before of a 38-150-SWC which cast too big to get the gas check on. I then read the directions and it said handgun sizes were based on 1 in 10 alloy. I started adding pure lead when finally at 8ww/2lead, the gas checks fit. Thats OK, It doesn't lead and it's accurate.
NOW, I bought a 44-250-K mould because it said it would be .430 with 1 in 10, and I figured a WW alloy would give me the .431 I needed. HA! Using the same 8/2 alloy the bullets didn't even make .430. OK, I'll go to wheel weights + 2% tin. Now it JUST BARELY makes .430. What Gives?

[beagle]

It seems as if the mass producers of iron moulds (RCBS, Lyman and Saeco) will not listen to their customers. As much as we have bashed them over the years because of undersize moulds, we still get 'em and they use the old saw that it's not the specified alloy that causes the undersize. Bull!

Let them make all the .44s to drop .433s with WWs and we'll resize. Guess we need to get up petitions to all of them and get this changed. Like trying to change the government./beagle

[462]

I had an RCBS 30-180-SP that was dropping less than .307". I sent it to them, along with some smaple boolits, and they replaced it with a new one that drops right at .310". Still, I would prefer .311".

[Ben]

Like trying to change the government./beagle

UUUmmm, then we really are in trouble.

[runfiverun]

i hesitated for over a year before buying my last mold hoping to find an older used one [no joy there]
i finally broke down and ordered the 4 cavity i wanted knowing it would be small.
sure nuff 428 barely.
one week later i now have then pouring to 430 barely [lapping and cleaning and pouring and lapping and cleaning]
i shoulda just spent the extra 20 bucks and got one made.

[44 WCF]

Undersize current moulds sure have been a nuisance of the past recent years, and one reason I went with Magma 2 cav moulds and a Master Caster. It's only 44 mould that dropped over .431 other than couple of older Lymans I had.

[Dan Cash]

I recently got a .38-55 1893 Marlin. A friend loaned me his Saeco mould that he uses for his modern gun so I could cast some until I got a mould of my own. They worked OK but droped a .376 with my desired alloy. I took the pllung and bought a 4 holer from Accurate moulds specifying a .381 base band. That is exactly what I got from all 4 holes and the bullets fit the throat in my rifle. To me, the custom mould was worth the money as it works and I am saved the frustration of tinkering with it to make it work. A word of caution, though; if you order from Accurate, be certain of your measurement as you get what you ask for.

[pdawg_shooter]

Last Lyman I bought was a 311284. With WWs the driving bands were .3085 and the nose was .297. Totally worthless to me. Took it to a gun show and got most my money back. I dont mind tweeking a 20 dollar Lee mold but for 66 bucks it better be right outta the box. Come to think of it my last 6 Lees have been right outta the box.

[Irascible]

Interestingly, I have an old Lyman 429421HP, Keith style, which I had Eric Ohlen redo the pin so I would have a choice of an original HP or a cup type. Anyway, this mould, using the 8ww/2lead + 2% tin casts at .432. So, why their same (new production) mould casts smaller is beyond me. I also have a 429244 which I had hollow pointed and had to have the bands opened to produce .431 with that same alloy?

[Mal Paso]

I like RCBS moulds. Good quality, BUT I wish their sizes were more accurate. I posted before of a 38-150-SWC which cast too big to get the gas check on. I then read the directions and it said handgun sizes were based on 1 in 10 alloy. I started adding pure lead when finally at 8ww/2lead, the gas checks fit. Thats OK, It doesn't lead and it's accurate.
NOW, I bought a 44-250-K mould because it said it would be .430 with 1 in 10, and I figured a WW alloy would give me the .431 I needed. HA! Using the same 8/2 alloy the bullets didn't even make .430. OK, I'll go to wheel weights + 2% tin. Now it JUST BARELY makes .430. What Gives?

If RCBS said 1 in 10 they were referring to Tin/Lead. A 10% tin bullet will tend to cast larger than Wheel Weights.

[Irascible]

I had to go check my CB references, I thought that only antimony controlled expansion. Tin does also, but not to the extent that antimony does. I'm not sure how 1/10 will work at 357 mag velocities. We'll see!

[stubshaft]

It works great at 357 velocities. IIRC - Elmer used 1 in 16 to develop the 44 mag.