New Hollow Base Mold Being a Challenge to Cast

I won a 462-420 MP brass with PB and HB pins . I was sooooo disappointed , brass is supposed this wonder mat'l for moulds and MP are supposed to be just all that .........

I cast 9 sessions and as many additional heat cycles before I got a really good everything right bullet . Oddly filling out bases and HB wasn't where I had problems , the noses looked great too , it was bases and the mould side of the skirts that just refused . More irritating than that it seemed to go from cold wrinkles to frost to too hot to even think about band fill out in about 3 pours but only on one side . At 12 casting sessions it cleaned up and we were talking to one another but weights weren't making me too happy . They were within 7-8 gr but didn't seem to have any particular pattern for a why ..... At the same time and alloy I was pouring a 457193 single and a 3 cavity 457132 NOE version 460-543 both at +- 1.5 gr . At 15 I got the pins , mould temp , pace and appearently enough patina on the brass .

Finally I got it all together and was consistent at 417 and 380 gr +- 1 gr , 2 PB ran within 2 gr and closer after I got the base pins paired up right . I really like it now , but I was just about ready to unload it cheap just to get rid of it .

I too have had more trouble then not with MP moulds. Definitely not my favorites because they require a terrible amount of "Lee-menting" under 20x magnification. One I had had raised teats in the meplat that locked the bullets in the cavities. It's a machining impossibility yet they were there until I shaved anthem off and blended with the eraser end of a pencil and Clover compound.

I wanted them to be better than they turned out to be for me as well. My biggest gripe is that I can't keep the top of the mould from heavy scuffing under normal use. I do well with aluminum blocks, but the MPs are a law unto themselves. I guess I'm just not a big brass mould fan. My gunsmith doesn't like the machining on the ones he bought at all.

Have not ben doing this that long and....I am just an idiot, so just ignore me if I am of no help.
But I ran into that problem when first casting.
Doubt if it applies here.
I was pouring a bit too cold as mentioned already, but I was also making my sprues too small so they would not retain a small puddle in the middle, and pull material down into the mold when cooling. I was getting hollow bullets.
Just a thought form the peanut gallery. LOL

I got back to doing some casting with the mold, and had much better results. I slowed the lead flow to a little more than a dribble and then opened it up a little from that flow rate. The void above the core pin is gone and I am getting decent fill out with the occasional slightly rounded driving bands on on maybe half the bullet diameter. A little tin would probably take care that. I will have to see how the shoot before throwing tin at it.

This is the rifle shooting them right at 1000 fps.

Damn. That looks like fun!

It sure does. I have no experience with anything larger than .22 airguns but have been drooling over some of the big bore PCP rifles for a few years now. Almost, almost bought a Sam Yang .45 with the bolt kit but wanted something with a moderator. Turns out from what I read most airgun moderators stink, so I'd be threading the muzzle and using one of my registered silencers anyway.

230 grains of soft lead at 1000 FPS is no joke for putting medium game animals in the freezer.

While back I was at the range talking a fellow with one, skeletinized with external tank 357 IIRC. Sounded puuuh - thunk. He was buying bullets but we talked about casting. IIrc he couldn't tell the difference between solid or hollow base. Sounds like you have it figured out, basically venting.

Loren said:

I got back to doing some casting with the mold, and had much better results. I slowed the lead flow to a little more than a dribble and then opened it up a little from that flow rate. The void above the core pin is gone and I am getting decent fill out with the occasional slightly rounded driving bands on on maybe half the bullet diameter. A little tin would probably take care that. I will have to see how the shoot before throwing tin at it.

This is the rifle shooting them right at 1000 fps.

Click to expand...

1000fps!!!!! In a "45"Caliber Air Rifle? I will defiantly have to add that to my wish list.

www.donnyfl.com is my go to for an AG supressor. Really nice machine work and they work.

Better than baking cookies.

How does PC work with the Air gun? Guy I talked to was concerned.

Loren's a bit modest; he's a wood sculptor like Ian. He did an excellent build documentary over on airgunguild.com of the stock on his airgun.

Inspired me to do some research.. Can not believe how far air guns have came. Some pretty impressive stuff. sure beats my .177 Chinese side charger,
It has benn well used and has evolved into a diesler over the years with the help of some Teflon seals. Most I can get out of it is 780fps and it is a small caliber.

My redneck engineered, jerry rigged, rebuilt, overused 70 Shanghai .177 pellet gun.

The PC works just fine with air guns. I don't think there is much need on the small bore rifles shooting diabolo pellets, but when moving into the mid bore (.25, .257, .30) and the big bore (.308+) shooting cast bullets the PC will keep them from leading up a barrel just like a PB rifle. I made a batch of BLL up and will be doing some testing of it to compare it to PC. The BLL would sure save some time.

Mitty you are still in the dark ages....lol.

Here is a shot string from one of my PCP's shooting a .30cal 46gr cast pellet.

This is right at 98FPE at the muzzle. Does a wicked smack down on squirrels and the like.
Shot count: 10
Low: 970
Hi: 974
Avg: 973
Spread: 4
STD Dev: 1.4
974
974
974
972
974
974
972
970
972
974

For size reference. .30 cal cast AG projectiles

Must resist....

BLL might work. I tried with 30/30 cast and unless I used a GC I got leading. IMHO they lost the BLL early in the bore. 170 gr PB with 10gr unique @ 1450 fps, soft alloy.

With an AG you don't have the powder burn and heat. Makes for an easier trip down the bore for a cast lead bullet. Surveys show 9 out 10 cast bullets preferr being launched from an AG.....lol

Here is some more AG eye candy.
.40 Cal and will produce 275 to 300 FPE.




.257 cal. Shots cast bullets from 60gr to 92gr. Will produce 175 to 190 FPE depending on bullet weight.



Will reloading components being in tight supply and wanting to not burn up what I have, it is a good time for Airguns. Go shoot all day and all it cost is "the lead" so to speak.

^^^^Wow, just WOW.