Lyman 457132 Postell cast weight

[Mr. Reaper]

I have been casting for my handguns for years. Now I am casting for a Shiloh Sharps LRE in 45-70. I am currently as of yesterday, casting the Lyman Postell 457132. Yesterday I cast about 300 of these monsters. I am using 20/1 virgin alloy at 770 degrees F, hand dipping from an 80 lb. cast iron pot. Temp stayed plus or minus degrees 5 F for the entire session. All bullets I kept were well filled out with sharp edges and clean sprue cuts, no tearing and gouges. Nearly all the bullets I cast were within plus or minus .2 grains of 528.4 grains. I read that others are casting this same bullet and alloy combination and getting final bullets at about 536 grains with the exact same mold. I am at a loss as to explain the difference in weight from mine and what others are getting. Could I be getting that same amount of air pockets that consistently or is this difference to be expected from mold to mold? Should I keep them or toss them back in the pot and try again? Any suggestions or ideas would be greatly appretiated.
Thanks!

[Harpman]

If I just fill the mould I get about 527 lowest weight, If I fill the mould and let the remaining full ladle pour into it over flowing I get 536.. (and better bullets). the head weight puts more in.

[bigborefan]

Mr. Reaper,
I brought this subject up on another gun board asking the very same question. I too get 528 gr Postells using a 1-20 alloy. I asked how Lyman comes up with 535 grs when most of their moulds are tested with their #2 alloy which would make them even lighter than our 528 grs. From what I understand, Lymans 457132 moulds have have veried in dimensions slightly since the beginning. Some of the others on the gun board that I asked this question on had cast bullets that were as much as .014" longer than the ones that I cast. Though .014" don't sound like much, it probably makes up the 7+ grs difference that others claim. Tey claim lengths of 1.429" with older Lyman moulds. My bullets measure 1.415" in length.

[38-55]

Hey Ya'll,
FWIW... I cast mine out of 'new wheel' weights and they weigh in at 526 and are 1.410 in length..
May be it's just manufacturing tolerances.... It's a good bullet that does well out of my big browning...
Calvin

[Harpman]

:veryconfu I get 536 with wheel weights !.....go figure:-D

[John Boy]

I cast a lot of Lyman 457132's using a bottom pour and never have been able to get consistent measurements:
Bhn 8.4 - 536gr - 1.424"
Bhn 10.4 - 522gr - 1.432
Bhn 14.3 - 334gr - 1.429
... and I'm anal about a pot temperature of 730 and consistent pouring rhythm

Los Angeles Silhouette Club
Shrinkage - Bullet Diameter, Inches
Alloy .308 .357 .452
Linotype .002 .0025 .003
Lyman # 2 .0025 .0025 .0035
Soft Lead .0035 .004 .005
From the above two tables it can be seen that the softer the alloy and the larger diameter the bullet that more shrinkage will occur.

[38-55]

Harpman sir,
What is the OAL of your bullet ? Fwiw I just ran a bullet through the old lee hardness tester and came up with bhn 13.4 or a .062 indent..
Calvin
Ps I used to think my bottom pour worked ok for this bullet but I seem to get better results with the lyman dipper...

[Mr. Reaper]

Harpman,
I'm going to try your suggestion regarding the head pressure thing and overflow. My bullets spec at 1.418" in length, .460" diameter, and .448" imediately in front of the front driving band. Thanks everybody for the quick responses. I just wasn't sure if it was poor casting on my part with air pockets, or just the differences in one mold to the next. I also have a 457125 I am going to try tomorrow too. Wonder what that will weigh at? Thanks again...

[Harpman]

mine is 1.424, and it is not round at all..the part where the mould closes will jump up to 461 from 458 oposite.....I ended up getting a PJ mould and am very very happy with it..the darn bullets jump from the mould when opened, are perfectly round and cast within 2/10 - 4/10 grain consistently......and, 8 out of 10 rams HATE it !!!!!!!!!!!, Also, for me that head pressure is what gives me more consistent weights more than anything, once I started to pay more attention to detail on every single cast, I got much better results.

[Mr. Reaper]

Cast 150 of these yesterday evening. Followed Harpmans suggestion on the power pour. Most cast between 515 and 516 with a few as high as 517 and a few as low as 512. Diameter is .458 and it is .448 directly in front of the first driving band.