What size and grade rod would be best to expand a Belisle 330 into a 660? I can drill out the ends myself and weld, but want to make sure I use a quality rod that doesn't flex or bend easily.

You can use the same size high carbon rod (7/16"?) and braze short sections of 3/8" brake lines to splice them together. Using the same size allows you the convenience of not having to modify the triggers much. I use heavy wire from electric fence for replacing the triggers but wire from yard sings works too. Done this with a few of my 330 Belisles and have had very good luck with it.

Or just lay your spreader rod next to the original jaws and tac In place.

I have used the brake line method with wire weld. I do like Beav's idea

I did that with a Duke and liked how it closed up the jaws like that on a Belisles but prefer to splice them on my Belisles. I find it easier to splice them as its less of a hassle in lining things up properly before welding things together.

I'm no help, I bought mine ready to go.
I figured it up and it only costed 8.00 per trap. More
Than I could of made them, so that was fine by me.
You will like got ten of them and use on every job.

I think scout must have meant putting 5/16”rod into 3/8” brake line.So I’m going to modify a couple this summer any more advice?What exactly is high carbon rod?Thanks in advance guys or gals.

Metal isn't my strong suit but my understanding is that cold rolled is tougher that hot rolled.

High carbon steel will respond to a normal heat treatment to harden and strengthen. Hot rolled and cold rolled metals most commonly come in very low carbon when heat treated it will only be case harden. The low carbon steel has to go through a much different heat treatment process to introduce more carbon during the heat treatment and is how most tool steels are made.
Cold rolled steel is a little stronger the hot rolled but really only it’s outer case is for it’s formed cold and the material is left under stress. But once you cut, grind, weld, or heat cold rolled you relieve the stress it’s under and is no stronger then hot rolled at that point.

Mad Scientist is right, it's 5/16" round stock but you want to use high carbon steel or it will be soft and bend possibly preventing a clean catch. Rebar is high carbon but not ideal for this application due to the exterior surface being textured and not smooth like regular round stock.

Just watch what rebar you get most rebar is made of a lot of recycled metal and junk and doesn’t contain proper amounts of carbon to be harden. Rebar is not hard steel just stock you can bend it easier than 1018 round stock. Metal behind high carbon doesn’t mean much unless it’s been through it’s proper heat cycle first 1070 or 1080 steel rods bend very easy but after proper heat treat good luck bending it.

So I asked the guy at fab shop if they had high carbon 5/16 rod and I got that are you from a different planet look and he said they have cold rolled and hot rolled.So can I heat treat myself and what would I buy to start with.I see a 1018 and 4041 steel rod online and the 4041 seems to be a very hard steel.Anyone know about the the steel numbering system and which one would work for these traps.

Nope, you got it backwards!

If I were placing BGs In wide channels I would just use 2 330s and just stagger them a bit so they weren't right next too each other.
Seems like a better option then re building some 330s into 660s

1035 - 1045 ... First two numbers are the alloy class, the last two numbers are the percent of carbon.

Benefits of Cold Rolled Steel

Compared to hot rolled steel, cold rolled steel offers a variety of advantages, such as:

Greater strength: Cold rolled steel can exhibit strength up to 20% greater than that of hot rolled steel, which makes it more suitable for use in high-stress applications.
Better surface finishes: Parts and products made from cold rolled steel generally have a smooth and shiny surface that is free of rust and scale.
Higher precision: Unlike hot rolled steel, cold rolled steel does not shrink after the forming process. This quality allows for the creation of highly precise components that require little to no secondary processing.
Applications of Cold Rolled Steel

Cold rolled steel is often used for applications that require tighter tolerances and better surface finishes. Typical parts and products include:

Aerospace structures
Home appliances
Metal furniture
Strips, rods, bars, and sheets
Mechanical Components
Key Differences Between


https://www.grobinc.com/blog/hot-rolled-steel-vs-cold-rolled-steel/

Maybe we should define “tough”. When you start bending/pressing steel, cold finish will crack and break long before hot rolled, so in that sense hot roll is “tougher”. Cold finish is more resistant to bending, so if we are talking stiffness and keeping shape without bending under stress, cold finish is “tougher”.

I’m seeing the harder rod priced at $5-10 a foot so I’ll try the cold rolled and see what happens.

The softer rod will bend and sometimes will not give you a clean kill. Nothing worse than a very upset XXL otter in your BG! Sometimes you can salvage some harder materials off of old farm equipment, much cheaper.

I agree with the beav.Why limit yourself to one catch at a location when you can make two or more catches on one check.