Modify plain base mold to take a gas check?

[gzig5]

Curious if anyone has modified a steel plain base mold to produce a boolit that will take a gas check. Going the other way is straight forward, just open the gas check base to the nominal bullet diameter in the lathe or mill. I want to shrink the base, which means adding material. The only way I've thought of would be to silver solder or braze half-rings into the base of the mold halves, file/stone till flat, and then remachining the base bore to the GC dimension and perhaps the first groove. I've searched and only found going GC > PB. Obviously a lot of work, but I have a couple molds I won't use as PB and it would be a fun exercise if there is a decent chance of success. Hardest part would seem to be the solder/braze operation, keeping excess material from flowing forward into the mold and filling grooves. Most silver solder solders don't flow until above 1100+ degrees so should stay put at lead melting temps.

[country gent]

Depending on bullet dia a thin buhing could be machined and split. thenn turned back to completely round with a pilot hole in it. It would have to be very square and parallel. O.d. to have 3/8-1/2 width around hole when finished. These could be held in with 4 small ( 6-48 or 4-48) flat head allen screws installed hot with red or green loctite. Let cure and then stake heads in place. machine top surfare lightly to bring together and faces to blend edges. Now you have your starting point to cut the gas cheeks area and blend to cavity. You cant thread this in as a bushing due to the 1/2 dia and split that needs to be maintained. 2 flat heads in each half and a soft dowel pin will maintain the alighnment good. Done right you could have inserts for plain base and gas check both. I would also ID each side together with a prick or number stamping, so you always know which one goes where. soldering brazing or welding could be done but at those temps you might risk warping the blocks. Ive seen some very good welder who could tig a ring around the top in each half and then machine it. Someone with that skill and preccision isnt cheap.It might be easier and cheaper to just buy the gas checked version if available.

[.22-10-45]

A thin plate of same material as mould blocks could be fitted to both block bases using small dia. flat head screws. mould set up in say a Bridgeport mill..indicating hole & replacing plates & drilling hole for G.C. I.D. The flat head screws will self center plate when re-installing. or small dia. dowels could also be used to maintain alignment.

[enfield]

Buy a new mould. You can NEVER HAVE TOO MANY MOULDS

[williamwaco]

Buy a new mould. You can NEVER HAVE TOO MANY MOULDS

+ 1

Not counting time, you are going to spend more money than a new mold would cost.

[Larry Gibson]

Buy a new mould. You can NEVER HAVE TOO MANY MOULDS

+1.

However I have been involved in making a GC'd bullet out of a PB'd bullet. Done correctly you'll end up with a bit lighter weight and shorter bullet. Mill off the base of the bullet to the beginning of the first lube groove next to it. The drill/ream or mill the lube groove part of the mould to be a GC shank of the correct dimensions for the GCs to be used. Of course the lube groove portion of the mould must have enough metal to allow this but most older FB'd cast bullet designs do. Refit the sprue plate and cast away.

Easier and probably just as cost effective to just buy the right GC'd mould to begin with, especially in this day with all the custom mould makers and standard designs commercially available.

Larry Gibson

[475AR]

Just use plain base gas checks, they work great. You can get them pre made or get the dies to make them.

[Mk42gunner]

There was a thread several years ago with pictures, where a member converted a mold much as .22-10-45 suggests. I do not remember who it was, but he did a good job on it. It did add about 0.050" to the length of the boolit, and a few grains to the weight.

So while it can be done, it isn't cost effective, even if you can do the work yourself.

Robert

[longbow]

My opinion... it is unlikely that you would get anything silver soldered or brazed in place accurately enough so would wind up having to machine after which is no easy task.

I hadn't thought of Larry's approach, that is one way of getting there and depending on lube groove style and size could work well.

PB gas checks is the first thing I thought of and for handgun boolits the reports are good. Not sure about rifle boolits at higher velocities.

As Mk42gunner mentioned, there was a thread a few years ago where one of the members here added plate to the top of the mould then machined it to provide a gas check shank. I can't recall if he milled the mould down by the thickness of the plate to keep weight the same or if he just added to the top of the mould as is. If memory serves it worked well for him but would be a lot of work and difficult to get the GC shank dead concentric with the cavity.

I think the advice given so far on trying PB gas checks or simply buying the appropriate GC mould are the best.

What mould is it? Handgun? Rifle? Intended velocity? Just curious why PB is no good.

Longbow

[gzig5]

I'm glad you all are so eager to spend my money. I have a pretty complete machine shop and since I've invested so much in machines and tooling, I tend to try to use it to solve whatever problem I'm looking at. So far the addition of a plate on the bottom seems like the simplest and most straight forward method. I'm not good enough with a TIG to build it up. Centering a mold in a lathe or mill is standard machine work, no different than setting a barrel up for chambering, so no problem there. FWIW the first mold I was going to play with is a Herter's 45300. It kinda looks like a tumble lube with multiple shallow grooves and it has a bevel base and a big flat point. Here's one that sold recently on ebay http://www.ebay.com/itm/Herters-4530...p2047675.l2557 I bought it to use in my Shiloh Sharps 45-70 but thought it would be a fun "express" bullet in a 458 Win Mag. I planned to remove the bevel anyway and it looks like a good candidate for a hollow point conversion too. I also have a couple mid-wieght 35's but no revolver anymore, so I thought I would check them so I can run them a little faster in my 35 Rem. The plain base checks are a potential option, depending on the alloy I end up with.

[MT Gianni]

Even a bottom plate will change oal. If you don't have a load worked up it is one thing but add the extra length and it will shoot differently.

[gzig5]

Even a bottom plate will change oal. If you don't have a load worked up it is one thing but add the extra length and it will shoot differently.

I would expect nothing else.

[w30wcf]

Years ago I was given a single cav. 311241 plain base mold. When I looked closer at it though, I found that someone had done a very nice job of silver soldering what appeared to be sections of a gas check or gas check thickness material into the back of the mold. The mold produced nice gas checked versions of the 311241 plain based bullet.

w30wcf

[dragonrider]

Add a plate to the bottom, mill the appropriate amount off the die, drill and tap to attach the plate equal in thickness to the appropriate amount you milled off the die. Keep the screw as close to the cavities as you are able. I would also drill and ream for pins for solid locating. The rest you know.

[Mk42gunner]

I'm glad you all are so eager to spend my money. I have a pretty complete machine shop and since I've invested so much in machines and tooling, I tend to try to use it to solve whatever problem I'm looking at. So far the addition of a plate on the bottom seems like the simplest and most straight forward method. I'm not good enough with a TIG to build it up. Centering a mold in a lathe or mill is standard machine work, no different than setting a barrel up for chambering, so no problem there. FWIW the first mold I was going to play with is a Herter's 45300. It kinda looks like a tumble lube with multiple shallow grooves and it has a bevel base and a big flat point. Here's one that sold recently on ebay http://www.ebay.com/itm/Herters-4530...p2047675.l2557 I bought it to use in my Shiloh Sharps 45-70 but thought it would be a fun "express" bullet in a 458 Win Mag. I planned to remove the bevel anyway and it looks like a good candidate for a hollow point conversion too. I also have a couple mid-wieght 35's but no revolver anymore, so I thought I would check them so I can run them a little faster in my 35 Rem. The plain base checks are a potential option, depending on the alloy I end up with.

No problem, I find it easier to spend other peoples' money than my own.

From the looks of the bevel base on the mold in your link, you are halfway to a gas check shank as it is. Since you have the machinery and knowhow to do it, I would say go ahead.

You do realize that pictures will be requested of the progress, don't you?

Time spent doing a hobby is something that may not make monetary sense; but it can give a wonderful sense of personal accomplishment.

Robert

[Motard]

Here it is the one I bought used and I waiting it to come. It is a vintage lyman 311241 suppose to throw out some 150/155 pb boolits. Withe the two plats screwed in place it throws 190 GC boolits. The nice thing is the modd is fulli reversible and the gas check shank can be fitted or removed as per needs. The bad thing I coul'nt yet try it and dunno if it waors or not. But must say that for the amount it cost me it was worth gave a try

[dudel]

How about a Harvey protexbore style gas check? cast with a zinc washer in the base. the lead acts like a rivet to keep it in place, the mold centers it on the boolit.

http://www.cornellpubs.com/old-guns/...hp?item_id=424

[45-70 Chevroner]

+ 1

Not counting time, you are going to spend more money than a new mold would cost.

Another +1 this sounds like an expensive proposition.

[gwpercle]

If you want to see a mould so modified, check out Motard's post, Lyman Mould W & W/O gas check, today 7:29 AM, looks like a nifty way to do it !
Gary

[Catshooter]

Is this what you're looking for? http://castboolits.gunloads.com/show...-check-feature


Cat