Convert GC mold to PB?

[RG1911]

Many years (decades) ago I bought a Lyman 358156 SWC gas check mold for my revolvers. It has never applied gas checks correctly using either my original Lyman 45 or my Star. Having unearthed my revolvers, I wanted to cast some boolits and did some online research into applying gas checks correctly.

The result is that I either need to buy a plain base mold or convert my GC mold to PB; something I've heard can be done.

If this is correct, what is the preferred method to use? In addition to Dremel and Fordham tools, I have a 1946 Delta drill press and a used Taig micro mill that I have been using on another project.

Thank you,
Richard

[fc60]

Greetings,

The best method, in my opinion, would be to index the cavity in a 4 jaw lathe chuck and carefully bore the step away. This way, the hole will be square and round at the base.

Trying to index the cavity on a stout milling machine and boring the step away would be a second idea; although, the lathe would be best.

Might be ideal to sell the mould and apply the money towards a Lyman 358429 or the RCBS 38-150-WC. There are other plain base moulds that can be considered.

Cheers,

Dave

[country gent]

This can be done but is a touchy operation. The cavity can be opened up thru boring or reaming. I think the mill is the easier way but that is personal opinion. Lathe will also work. Set up is the key and most important step. a decimal hand reamer can be bought to remove it also. Another way is to mill face the blocks down to remove the gas check base. Whatever you do the work has to be square and true.

I would try shooting them with out the checks as is and see if its worth the work

[GregLaROCHE]

I have an aluminum Lee mold I’ve been thinking about doing the same thing to for a couple of years. After thinking about it I decided a four jaw chuck would be best. I haven’t done it yet partly because shooting without GCs seems to work well enough for me. I’m taking about a 45/70 boolit.

[nicholst55]

Or you can send it to Eric at Hollow Point Mold Service and have him do it.

http://www.hollowpointmold.com/

[derek45]

A few years ago a member here offered to mill my LEE 430 310 to a flat base 270

It came out very nice, but I have to admit, . . . I like my Arsenal 503 Keith mold better

https://i.imgur.com/4JMQu17.jpg

[Gewehr-Guy]

If using a four jaw chuck on an aluminum mould, be sure to shim under the jaws with some flat stock, as a jaw over the center of a cavity, will easily distort the cavity out of round.

[Ed_Shot]

Or you can send it to Eric at Hollow Point Mold Service and have him do it.

http://www.hollowpointmold.com/

+1 Eric does outstanding work.

[GregLaROCHE]

If using a four jaw chuck on an aluminum mould, be sure to shim under the jaws with some flat stock, as a jaw over the center of a cavity, will easily distort the cavity out of round.

That’s a very good point. If I do it one day I will be sure to remember it.

[imashooter2]

-snip-

I would try shooting them with out the checks as is and see if its worth the work

The best advice in the thread.

[Larry Gibson]

"I would try shooting them with out the checks as is and see if its worth the work"

Definitely good advise.

Or, you might just sell the 358156 mould on the for sale forum and buy a PB mould.

[Green Frog]

Another vote for trying them without the gas checks. I can’t remember when I last actually used gas checks on one of my gas check design bullets. Think of it as a sort o large, square sided beveled base! :bigsmyl2:

Froggie

[RG1911]

Since I don't have a lathe or a professional-level mill, I'll either buy a PB mold, such as the Lyman 358429, or check out hollowpointmold.com. Shooting them without the gas check isn't the problem; it's the mess made by the lube when it isn't contained by a groove. (A possible problem associated only with push-through dies, such as my Star.)

Cheers,
Richard

[georgerkahn]

I'm a bit confused -- perhaps I've been doing "something wrong" for the past 40 to 50 years... I never was concerned with the gas check step. The way I viewed it then -- and still do -- is that I have the ability to apply a gas check, primarily (if not solely) based upon my shooting performance. I'll shoot maybe 20 without a gas check applied. IF they group OK on target, and leading is non-existent or little enough to enable me to shoot more in a session before lead becomes a challenge -- then I simply stay with it.
If "????" -- lead too soft for load; or, velocity to high sans a gas check; or, "???(I have no idea)??? -- then I'll apply a gas check. For what it's worth, too, I have those little Gizmos Lyman makes and sells for the 450 family lub-sizers, and that's what I exclusively use. I've had zero problems in adding a gas check to a previously sized and lubed bullet, as well.
geo

[imashooter2]

Since I don't have a lathe or a professional-level mill, I'll either buy a PB mold, such as the Lyman 358429, or check out hollowpointmold.com. Shooting them without the gas check isn't the problem; it's the mess made by the lube when it isn't contained by a groove. (A possible problem associated only with push-through dies, such as my Star.)

Cheers,
Richard

I thought the whole point of the Star was the system allowed you to fill only the grooves you wanted to?

[Springfield]

If you are filling the gas check groove with lube then the problem is improper use of the Star. Assuming the die has the proper holes opened up, then you either have too much pressure to too warm a lube, or both. I lube/size hundreds of bullets a week for the 4 shooters in my family, and don't have this problem if I do my part.