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Steven66
03-13-2018, 06:52 PM
I used an LBT slug to make my pound cast. It was about 0.020" less than the bore size. I went through the procedure and the slug came out easily, but no rifling marks appear. I need to have it long enough that rifling shows, correct?

I made some slugs much closer to bore size by casting them in drilled holes in a block of wood (sassafras) . They didn't come out smooth. I've been thinking about making some more using plaster of paris and using the drill shank to make the slug holes. I'm a little concerned about any residual moisture contacting molten lead. If not plaster of paris, is there some other way to make a disposable mold? Maybe use denser wood instead?

Grmps
03-13-2018, 06:59 PM
http://castboolits.gunloads.com/showthread.php?356251-Pound-Cast-instructions-(for-rifle-chamber)

Tom Myers
03-13-2018, 07:20 PM
I used an LBT slug to make my pound cast. It was about 0.020" less than the bore size. I went through the procedure and the slug came out easily, but no rifling marks appear. I need to have it long enough that rifling shows, correct?

I made some slugs much closer to bore size by casting them in drilled holes in a block of wood (sassafras) . They didn't come out smooth. I've been thinking about making some more using plaster of paris and using the drill shank to make the slug holes. I'm a little concerned about any residual moisture contacting molten lead. If not plaster of paris, is there some other way to make a disposable mold? Maybe use denser wood instead?

Steven,

I do this and it works quite well.

Hard-wood Slug Mold for Chamber Impact Impressions (http://www.tmtpages.com/draw/HelpfilesUlt-5/hs155.htm)

You can use a file or sand paper to dress down the portion that will imprint the throat and leade a little smoother.

Hope this helps.

Steven66
03-14-2018, 11:21 AM
Thank you. I had read the pound cast thread and had made wood-mold slugs before I posted. The LBT slugs I bought are just too small. The slugs I cast from holes drilled in wood were a snug slip fit into the bore. I made two slug impressions and I can't get the rifling to show clearly (I can see one partial groove). The drive rod is extruding the slug around it and still no rifling marks. I'm frustrated and ready to give up and I don't want to damage the barrel. Is it even possible to get a well-fitted mold without making a chamber cast? I want is one that will make a 158-ish grain (using COWW metal) round flat nose/wide flat nose gas checked boolit. I'm more than willing to try a brand other than LBT if there's a way to do it. I don't wish to imply anything negative about LBT; I just can't get a decent pound cast to send along with my mold order.

Tom Myers
03-14-2018, 12:50 PM
Thank you. I had read the pound cast thread and had made wood-mold slugs before I posted. The LBT slugs I bought are just too small. The slugs I cast from holes drilled in wood were a snug slip fit into the bore. I made two slug impressions and I can't get the rifling to show clearly (I can see one partial groove). The drive rod is extruding the slug around it and still no rifling marks. I'm frustrated and ready to give up and I don't want to damage the barrel. Is it even possible to get a well-fitted mold without making a chamber cast? I want is one that will make a 158-ish grain (using COWW metal) round flat nose/wide flat nose gas checked boolit. I'm more than willing to try a brand other than LBT if there's a way to do it. I don't wish to imply anything negative about LBT; I just can't get a decent pound cast to send along with my mold order.

Steven,

What caliber and chambering are you working with?

The end of your drive rod should be as close to bore diameter as possible without possibly damaging the bore.

If the end or your rod is significantly smaller than the bore, maybe you can use a small caliber empty case to slip over the rod and then file the case rim to just slide into the bore.

Or you could start a gas check of the same caliber as your bore into the muzzle, then place a small wad of paper in the cup of the check, then the rod should be able to give a good impression without piercing either the check or the lead slug.

This link will give some more detail on the process

Chamber Impact Impression (http://www.tmtpages.com/draw/HelpfilesUlt-5/hs40.htm)

Getting a well fitted mold without knowing your chamber neck, throat and leade dimensions will be, at best, a cut and try method.

If just can't get the impact impression to work, You could do a Cerrosafe casting of the chamber. If you do go the casting route, remember that the CerroSafe shrinks for about 30 minutes after casting and then begins to expand at a steadily declining rate for a long period of time. The casting expands back up to chamber dimension in about an hour and 20 minutes.

You can learn more about it here. Cerrosafe Chamber Casting (http://www.tmtpages.com/draw/HelpfilesUlt-5/hs30.htm)

Hope this helps.

Larry Gibson
03-14-2018, 12:55 PM
I also prefer to use cerosafe. When used correctly as per the instructions it works very well, better than the pound impressions I used to make. Nice thing is the cerosafe can be used over and over. It also is excellent to remove a separated case stuck in the chamber.

Steven66
03-14-2018, 06:22 PM
Steven,

What caliber and chambering are you working with?

The end of your drive rod should be as close to bore diameter as possible without possibly damaging the bore.


Cartridge is .357 Magnum in a Ruger 77/357. I used a 5/16" cold rolled rod covered in masking tape to be a snug slip fit in the bore (per LBT instructions). It sounds like cerrosafe would be a lot easier at this point; guess I'll order some. That said, where do I need to measure after the cerrosafe casting has come up to chamber size (about an hour after casting I guess)? Just in front of the case mouth and at the rifling? The nice thing about the pound cast is that I can just send it to the mold maker.

Tom Myers
03-14-2018, 07:54 PM
Cartridge is .357 Magnum in a Ruger 77/357. I used a 5/16" cold rolled rod covered in masking tape to be a snug slip fit in the bore (per LBT instructions). It sounds like cerrosafe would be a lot easier at this point; guess I'll order some. That said, where do I need to measure after the cerrosafe casting has come up to chamber size (about an hour after casting I guess)? Just in front of the case mouth and at the rifling? The nice thing about the pound cast is that I can just send it to the mold maker.


Steven,

Make a sketch of the chamber with, at least, the dimensions outlined in red in the first image below. Also send along a fired case or two.

The mold mfg. should then be able to design a bullet to fit the fired case and free-bore, with sufficient length to contact the rifeling when crimped in the crimp groove.

The second image below is entirely computer generated using the Cast Bullet Design & Evaluation ~ Ultimate (http://www.tmtpages.com/#ultimate) software using chamber dimensions and generally accepted, optimum cast bullet design parameters but could be modified as desired.

http://www.tmtpages.com/LinkSkyImages/forum_images/Chamber%20Impression/Chamber&Case.bmp


http://www.tmtpages.com/LinkSkyImages/forum_images/Chamber%20Impression/Chamber&CaseDimensions&Bullet.JPG

GhostHawk
03-14-2018, 09:15 PM
I have been known to slip 2 slugs into the bore in order to get far enough in some cases.

My .357 handi rifle was one.

Bored long enough to accept untrimmed .360dw brass and still I have to crimp in the top lube groove to get close to the rifling.

Hang in there!

MGySgt
03-16-2018, 12:32 PM
I want is one that will make a 158-ish grain (using COWW metal) round flat nose/wide flat nose gas checked boolit. I'm more than willing to try a brand other than LBT if there's a way to do it. I don't wish to imply anything negative about LBT; I just can't get a decent pound cast to send along with my mold order.

You really need to be using pure lead, not COWW. The stick on WW will work also. COWW is jst to hard to make a good pound impression.

blackthorn
03-17-2018, 12:04 PM
I prefer to use Lead wool to do a chamber pound impression. Lead wool is hard to find here likely due to the Chicken-little Greenie-Weenies. An alternative to a Cerosafe cast is to use Graphite/Sulfur.

An alternative to using Cerosafe or the pounded slug method is to make a sulphur or sulphur/graphite cast. To do this, make up a mixture containing a ratio of approximately two-thirds sulphur to one-third powdered graphite. Sulphur requires a much higher melting temperature than Cerosafe but it has the advantage of neither growing nor shrinking significantly once the cast has set. Sulphur chamber cast info in an old Dixie catalog provided a measurement of -0.003” shrinkage at 48 hours, but if you mix 1/2 a tablespoon of powdered graphite with 1/4 cup sulphur, the shrinkage reduces to -0.0015” to -0.0017” at 48 hours. Once this initial aging has occurred, no further change to the casting takes place. As noted, a chamber cast can be made using just sulphur but these casts tend to be somewhat hard to remove and they tend to be brittle. The addition of graphite in the casting makes it less brittle and easier to remove once it has hardened.

A container of sulphur can be had cheaply at the garden center. Clean and degrease the chamber, put a paper plug about one half inch into the rifling, drop a piece of cotton string into the chamber, do not use synthetics, have a wood dowel longer than the barrel and of smaller but as close as possible to the inside diameter on hand. Alternately, you can make a barrel plug out of cork or other stiff material, attach the required cotton string through the plug and push it into the chamber/barrel. Place some sulphur in a small pan with a pour spout, using, preferably an electric hot plate, slowly heat the sulphur until it melts, do not let it catch fire, the smoke is () poisonous. Stir in the powdered graphite and pour in enough of the liquid mix to just fill the chamber, wait until the cast is completely hard, this will depend on how large the chamber is, which governs the mass that has to cool down. Carefully push on the cast with the dowel while firmly pulling on the string; it should come out easily once it starts to move.


As noted, unlike Cerosafe, Sulphur cast dimensions of the chamber do not change at all over time, even after many years, so how soon after casting you measure the cast is not important. Sulphur is one of the few elements that do not change dimensions when going from a liquid to a solid state. Molten Sulphur can also be used to set machinery anchor bolts in concrete.

The inclusion of graphite allows the casting to release very easily after it cools. While not critical, the best ratio, is somewhere between ten and thirty percent graphite. Use a piece of poly tube through the receiver, pressed firmly against the rear of the chamber to keep from spilling it all over. Stick a funnel in it and pour until you see it in the tube. These castings can be remelted for re-use or they can be marked for identification and kept for future reference.

Steven66
03-17-2018, 12:51 PM
You really need to be using pure lead, not COWW. The stick on WW will work also. COWW is jst to hard to make a good pound impression.

Sorry, wasn't clear on that. I used pure lead (from purchased BP roundballs; hope it's pure) for the chamber slug. I want to use COWW as the boolit alloy.

Possibly a factor: I held the rifle by the barrel in my left hand while using my right hand to pound with the maul head. I just couldn't see whacking on the drive rod with the stock butt resting on the floor for fear of hurting the stock. It seems to me that the lead slug should fill out anyway because it should deform each time it gets pounded, up until the chamber is completely filled. When I try it again, I guess I'll take the action out of the stock and rest the rear tang on the floor.