Molding and casting real firearms

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DrewSmith007

Well-Known Member
RPF PREMIUM MEMBER
I've got a few less than common guns that I would like to make some molds of. Has anyone done this, and if so, what problems did you run into and what tips can you share?
 

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robstyle

Master Member
It depends on how far you want to get into it and how much prep time you want to take. For the Man With No Name 1851 Colt Navy revolver I did for Halloween the entire gun was disassembled and cast in separate parts. Not a rare gun by any means but ive yet to see anyone offer castings of one especially a cartridge conversion.

For an automatic I mold the slide and bottom section separately as well as the bottom of the magazine. This allows a cleaner end part when assembled.

Keep your seam lines in mind as well as any undercuts. The casting material is also to be considered when doing the mold prep. If its a slower setting material will it hold up to being dropped or typical handling by someone. A faster setting material may not fill the trigger guard so vents may need be cut into the mold...

One thing that always bugs me with castings is a lazy clay up job where the lines are flush. Push that clay in a little and cut that line deep enough to keep the visual alive. No reason to have a final casting thats in dire need of its lines being sharpened. This is an example of what im talking about. Most people would clay in a cylinder near flush where I clayed it in deep enough that when the final part is completed and the cylinder mated to the gun nothing more need be drilled out minus the center hole thats necessary to install it. If need be all holes can be drilled out and shells could be loaded. Since the base plastic its cast in is black no further color/paint work would need be done either.

Original in the middle.
 

jasonw2112

Sr Member
RPF PREMIUM MEMBER
Nice info here! I've been wondering about this as well, but have not found the time (nor place) for
casting.

Not to mention I would love to get one of the revolvers you have been working on!
 

Mr Webber

Master Member
I've got a few less than common guns that I would like to make some molds of. Has anyone done this, and if so, what problems did you run into and what tips can you share?
Very interested in less than common guns in plastic, can you let us know about some of your collection?

Excellent work robstyle.
 

robstyle

Master Member
Also the trigger is the most prone to breakage part and the very first thing people want to make move even as you look them in the eye and say "please dont pull the trigger its solid and you will break it", they do it anyways. If you know how to tear the gun down and rebuild it, remove the trigger and mold it separately. They are simple to install on a casting with a pin, screw, carpet tape or buytl... anything that will hold it in place. That way when its broken it can be replaced.

The hammer is another area on many guns that is broken due to the same with the trigger. People just want to make something move that doesnt.

Some handguns will have details in the grips that could result in air bubbles on the surface. This is normal with something like a .45 Colt 1911 or similar. When possible mold the grips separately as well. It is more work but very simple work. You will thank yourself compared to the potential parts failure and wasted material of air bubbled parts.


For anything molded as a solid piece (revolver or automatic where you wont mold the slide separate) I assume youll be pouring material into a closed mold. The pour spout needs to be on the tallest part of the mold where air pockets have the least chance to build and material high enough to fill any voids. This is typically the barrel tip. You can make a smooth and flush spout by either casting in a dowel into the barrel and out a few inches or removing the silicone material with a sharpened hollow metal rod when the mold is completed. The sharpened metal rod is the same principal as a hole punch yet will be sharp as a knife. You can sharpen brass tube with an xacto knife (inside not the outside), fingernail file, bench grinder... I also polish the exterior tip so it doesnt get caught up on deep cuts.
You will need to add another small vent for air to escape or else your going to get burped. The vent doesnt need to be very large but just enough for excess air to escape when pouring material in. Can be off the trigger guard or lower slide/frame.

Its a small learning curve with any mold. Start with the most simple one you have and work up from there.
 

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robstyle

Master Member
Thats way beyond my concentration threshold. I cant walk and chew gum much less work and take pictures.
 

DrewSmith007

Well-Known Member
RPF PREMIUM MEMBER
Wow, thanks for all the advice Rob.

Unfortunately, I may have misrepresented what I'm doing. The guns I have aren't exactly rare, they're just not commonly reproduced in replica forms like airsoft.

The three I'm planning on casting are a Smith & Wesson SW990L, a Walther PK380 and a Taurus Model 92 22LR revolver.

I want to use the 990L to make a BSG style service pistol with a custom rocket tube like the five-seven has.

The taurus will be used as a test piece for a Mal pistol base. I will (eventually!) be cutting the handle off to weld on the cowboy style grip frame and I don't want to do my test cuts on the actual pistol.

I don't have a reason to mold the walther, but I just like it.
 

robstyle

Master Member
Its not cheap to mold and cast parts so spend wisely. You can still get cheap resin for abut $30 a gallon but its just that, cheap resin. I dont touch the stuff myself. Its brittle, tends to leach or hold air bubbles, cant withstand a short fall... I use a high impact plastic but its about $100 a gallon, but you get what you pay for.
Same with silicone, cheap is cheap.
 

DrewSmith007

Well-Known Member
RPF PREMIUM MEMBER
Yeah, I've noticed just how expensive this stuff is. All I've used is the stuff from hobby lobby. It seems expensive, but it's hard to know with Hobby Lobby prices being as inflated as they are. What is a quality resin and how does it compare to the Hobby Lobby stuff?
 

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robstyle

Master Member
Ive never used anything from Hobby Lobby so I cant comment. What I have handled before, dealing with resin, is as before mentioned. Just not worth the end result.

Here is a picture of the sharpened brass tube. Just cut the inner out to a point with the x-acto blade and you can stick it through a turkey. Once polished its extra cutter'ific. Everyone uses an x-acto to cut vents and channels in molds yet this is what I use. Polished with a dollar store nail file.

 

Noeland

Master Member
Yeah, I've noticed just how expensive this stuff is. All I've used is the stuff from hobby lobby. It seems expensive, but it's hard to know with Hobby Lobby prices being as inflated as they are. What is a quality resin and how does it compare to the Hobby Lobby stuff?
Smooth-on is a great place for beginners to start. They sell some great starter packs, and have many how-to videos, and tutorials online to help you take the plunge.

My current favorite resin from them is Black Onyx.

Smooth-Cast® ONYX® Black Plastic Product Information | Smooth-On
 

robstyle

Master Member
You can use a better plastic from MPK, also available in black.
Casting Resins, cast, resin, hobby  clear resin, hobby, professional, high quality resins

Smooth On is the larger vendor, has many website tutorials and such. First hand, after having some bad batches of plastic from them and leeching issues on larger parts I just cant recommend their product. Most vendors dont take into account prior shelf life or possible moisture contamination when they take in a product as it may have sat on a shelf or in a warehouse for a period of time, even on their own dime. A few smaller vendors are on top of these issues. Id rather deal with a person face to face than mail order anyways.

That being said ive had issues with Burman's products over the past year. Issues with inconsistent rubber and foams more specifically. Always stick with what you know and trust until its time for something new. With materials change isnt always good but when it does happen it can be the light at the end of the tunnel.
 

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