I'm looking for a mould picture

358156 hp

At large, whereabouts unknown.
I'm looking for a picture of a specific hollowpoint bullet mould. I think I originally saw it in one of Glens articles or posts. but I don't remember exactly when. It was either a two or four cavity (Lyman?) mould that had been converted to hollowpoint on all cavities, similar to one of Erics "inset bar" design. The major difference was that the bar that carried the hollowpoint pins was square, and the mould had been milled out at the bottom for it in such a manner as to be flush with the base of the mould. The bar could very well have been made from key stock.

I'm not 100% certain that this pic was even on this site, but if I saw it somewhere, there is a high probability someone else here saw it too. Any help with this would be greatly appreciated.
 

Brad

Benevolent Overlord and site owner
Staff member
Got any detail on how that was done Keith? Looks like it would work quite well.
 

KeithB

Resident Half Fast Machinist
It works great, the bullets weigh about 210-212 grs. I have an identical two cavity that casts about 228grs with my alloy. The HP pins are stainless steel bolts with the heads cut off. The cross pins are retained by the HP pins. I did not put any C-clips or anything on the cross pins, it is free to slide all the way out for cleaning. Here are a couple of shots of construction.

By having the pins buried in a fairly large block and since I keep the mold shut to retain heat the pins stay warm and I can cast as fast with it as I can the non-HP version.

I didn't do it expecting to get expansion, mostly I just wanted a little lighter bullet with a round nose that would feed in any .45.

I've seen prettier jobs, I think by Erik Ohlsen(?). He rounds the ends of the pin retaining bar and leaves a rounded end on the underside slot so it does not show from the ends. This was my first so I was just happy to get function, the next ones will be prettier.

hpmold1.jpghpmold2.jpg
 

Brad

Benevolent Overlord and site owner
Staff member
Interesting how you used the threaded section of the HP pin to hold the cross slide pins. Neat construction.

How did you index for the milling for the bar?
 

KeithB

Resident Half Fast Machinist
I wanted to minimize the number of parts so making them interlock accomplishes that.

I think I put the mold in the mill vise upside down and cut the slot first. Then I drilled the cross holes in one mold half and the pin holder bar, inserted the bar and pins in the mold. and put the whole assembly upright in the vise. I used a centerfinder to find the center of each cavity and drilled the mold, pin holder bar, and cross pins all in one setup. I think I enlarged the pin holes in the mold to the OD of the pins because I must have used the tap drill to drill the initial holes. I'm pretty sure the pins were made from a #10 (10-24?) bolt with a nominal OD of about 3/16 (.188)"
 

Brad

Benevolent Overlord and site owner
Staff member
And now I have another project. I have a Lyman 429421 I have messed with some already so it would be a good candidate for experimentation.
 

KeithB

Resident Half Fast Machinist
Sound like a great project, with a magnum you can get enough velocity for reliable expansion. You will learn to decide what surface you want to line up off of. the ones I've measured sometimes aren't very square. I think I used a dial indicator on the top surface as a final check, hoping that would be the way Lyman did it.
 

Brad

Benevolent Overlord and site owner
Staff member
Not being square is something Buckshot mentioned when he was doing Hp conversions. First thing will be doing some checking of the mould.
 

358156 hp

At large, whereabouts unknown.
That actually appears to be the mould I was remembering. A friend of mine is looking for a winter project and I thought of this HP method. Keith, you're a genius, and an inspiration!
 

KeithB

Resident Half Fast Machinist
No genius, just a pretty good copier of good ideas. Lots of folks have done much prettier work. Love to see what Brad and your friend come up with. I have made molds from scratch and I've altered several existing molds and I understand first hand why HPing molds is a time consuming PITA. If I'm already lined up to make the cavity in a new mold I'm also lined up to drill the HP hole and have it come out centered and straight. Not so on some existing molds, getting the cavities straight so the HP pin hole is straight AND concentric can be a real challenge.

Not to offend anybody, but some of the same people that will take a dull twist drill to gnaw on a mold to cut out a bevel base or GC shank are also the ones that will b***h if the price of a professional HP conversion costs more than a Big Mac or if the HP pin is .001" off center. Trust me, nobody that does professional HP jobs on your molds is getting rich. I know I won't do that kind of work for anything besides my own amusement.
 

358156 hp

At large, whereabouts unknown.
Ironically, most of the people who holler about an HP pin being .001 off center are incapable of measuring anything that precisely, much less a production bullet mould cavity in a block that doesn't have square, perpendicular sides, nor a cavity that was never perfectly centered in the above mentioned unequal parallelogram to begin with.
 
F

freebullet

Guest
At home inset bar hp conversion...priceless.

Something I have thought about but lack the tools to do. That is a labor of love there. Thanks for sharing.
 

KeithB

Resident Half Fast Machinist
This could easily be done on a table top milling machine. I used a lathe to turn the pins but the shaping of the pins was done with a file and could be done in a drill chuck or collet in a mill. I know, if you don't have one that's no consolation, just pointing out that it wouldn't take a full size knee mill, it is a project that is within the realm of smaller hobbyist type equipment.
 

Ian

Notorious member
I did a hollow point conversion on one of the newer Lee 2C moulds....using a drill press. It was centered pretty well in the nose, but slightly crooked. If I attempt it again, I will turn a 2"-long drill bushing on my lathe to pilot off of the mould's driving bands and ogive and drill/ream with that using the drill press. The only other thing I can see to do that would indicate the cavity itself true rather than guessing which of the 12 surfaces is true to cavity center-line is make an indicating rod to fit the cavity in the same manner and bump the mould blocks around in the 4-jaw lathe chuck until the rod indicates true and straight, THEN spot, drill, and ream the hole.