Alum or Brass mold question

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Joined: Fri Apr 20, 2012 5:33 pm

Alum or Brass mold question

Post by NFG » Fri Apr 20, 2012 7:04 pm

Got a problem...maybe :shock: :?

I have a caster that does my bullets and he uses a 1/3 WW, 1/3 Lino, 1/3 lead alloy mix then adjusts to a BHN of 16.

You made me a two cavity XL alum mold for a 700 gr, 0.625" as cast, 50% meplat, 0.500" nose length, 0.100" front banc that is producing bullets running about 665 gr plus/minus a couple and also producing 0.629-0.630" OD bullets....the description tag went out with the trash and he has the mold so I can't measure it for about two weeks while he makes me another 250 and I see him at the gun show...I THINK I ordered a 0.625" as cast but may have messed up.

The rifle is an NEF 20 ga USH and I slugged the bore at 0.619" and the grooves are ~0.632" using one of the cast bullets, and so far the accuracy isn't doing very well...4-5" patterns at 15 yds, using several powder amounts in new Cheddite 2.96" 20 ga plastic cases both heat crimped and roll crimped.

The best group I got today was a 7/8" CC using bullets I chucked up in my lathe and turned down to a ~70% mep, ~0.800" long, 0.300" nose length and ~600 gr final weight...roll crimped once fired Cheddite cases, AA 2495 powder, chronoed at 1642 fs. I want to use those dimensions and ~735 gr which should cast at 700 gr as far as the present runs are doing...casting about 35gr light with his mix.

I want to order another SINGLE CAVITY mold for a truncated cone nose, 3 grease groove, no crimp groove, 0.300" nose length, 0.110" front band bullet but in BRASS this time, SO

My question is....just HOW/WHICH numbers to use in the design program and WHAT alloy to pick to arrive at an AS CAST 700 gr slug at ~0.623- 0.625 OD using his alloy mix?? :?: :?: :?


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Re: Alum or Brass mold question

Post by mtngun » Fri Apr 20, 2012 8:10 pm

You specified 0.626" which means it probably drops around 0.627" with wheelweight. That assumes the faces of the mold are clean. Very common to get lead splatter on the faces which prevents them from closing completely and throws the diameter off.

Brass blocks are for wheelweight only. Tin can solder itself to brass if the mold is accidentally overheated.

Nor do I recommend anything but wheelweight for a 700 gr. bullet.

My molds are not intended to be cast with any alloy other than the alloy that you specify. I make no claims about diameters or weights with any other alloy.

Furthermore, using the wrong alloy WILL damage the mold. My WW sprue plates have large sprue holes that put a lot of stress on the block with any alloy other than WW.

I cannot help you with your alloy. It is the wrong alloy for a big bore bullet.

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Joined: Fri Apr 20, 2012 5:33 pm

Re: Alum or Brass mold question

Post by NFG » Sat Apr 21, 2012 8:23 am

Thanks for the info...I shoot several 45-50 cal cartridges with "store bought" cast lead and brass slugs I turn myself, but his is my first tentative step into the "DIY" casting world, I have a lot to learn.

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