Put action without bolt in vise. Use strap wrench on barrel. Turn correct direction.

 

I would not put the action in a vise unless you have some type of hard wood block to protect it. I used a mechforce barrel vise(there are others similar) and new leather pads with pine tar rosin on both the upper and lower leather pads, sprayed barrel with kroil everyday for 3 or 4 days, then put it in the vise, tightened the nuts with a lot of torque i used a 3/4 inch drive 6 point impact deep socket and ratchet. The first try the barrel started to spin so I stopped and re tightened the 4 nuts again. I used a 24 inch action wrench with another 25 inch breaker bar it finally broke loose on the second try. The leather was toast after that but it worked. I have done two marlins this way both times I had to use the extra breaker bar to break it loose they a were extremely tight.

 

While I never had to use them, I did buy some lead shims that I was going to use as the next plan. Midwayusa sells them cheap but I think they would work very well also.

 

I would gut the action and put the bottom part of the action back in and tighten the screws to help strengthen it. Also use shims to protect the action.

 

+1. Gut the action and put the bottom plate/trigger mount back in. Leave the breechbolt out. It takes some torque to separate the receiver and barrel, keeping the bottom plate in will stop the receiver from warping. A really stout barrel vise is needed. The 4 bolt vise from Brownell's is strong enough.
Don't forget to mark the barrel and receiver so as to reassemble with the front sight at 12 o'clock high.

 

I've used leather and rosin, lead (chimney flashing), or depending on the type of barrel, aluminum inserts. Make sure you put the trigger housing in as Rob said above and tighten the screws. I haven't yet pulled a barrel on a Remington made Marlin so not sure if they used loctite or rocksett. If so, you need a bit more heat than just warming it up. I've had to heat a few over the years and use an electric heat gun. Some folks use a propane torch but I prefer a more even heat from the electric gun. Not sure what you had for a receiver wrench but it shouldn't have broken. For most of my work, I have a wrench made for the M1 Garand that also works ok on flat sided receivers like Marlins. I use leather on the sides to protect the finish. I haven't lost a battle yet, but I've had a few that ran me to the edge of wanting to surrender. The worst stuck one I ever did was an 1881.
For a penetrating oil, make a 50/50 mix of ATF and acetone. Use caution and don't use heat while it's still soaked and wet unless you want to burn things down. It will creep into the threads way better than Kroil or other thin oils, unless it has loctite or rocksett on the threads.

 

I've used leather and rosin, lead (chimney flashing), or depending on the type of barrel, aluminum inserts. Make sure you put the trigger housing in as Rob said above and tighten the screws. I haven't yet pulled a barrel on a Remington made Marlin so not sure if they used loctite or rocksett. If so, you need a bit more heat than just warming it up. I've had to heat a few over the years and use an electric heat gun. Some folks use a propane torch but I prefer a more even heat from the electric gun. Not sure what you had for a receiver wrench but it shouldn't have broken. For most of my work, I have a wrench made for the M1 Garand that also works ok on flat sided receivers like Marlins. I use leather on the sides to protect the finish. I haven't lost a battle yet, but I've had a few that ran me to the edge of wanting to surrender. The worst stuck one I ever did was an 1881.
For a penetrating oil, make a 50/50 mix of ATF and acetone. Use caution and don't use heat while it's still soaked and wet unless you want to burn things down. It will creep into the threads way better than Kroil or other thin oils, unless it has loctite or rocksett on the threads.

I was reading a discussion on using rosin and one guy said he used powdered sugar instead of rosin. He said it worked better. Just a thought.

 

Make sure the front scope mount screw is removed as that hole goes through to the barrel threads and can lock it in place. I've always just put some Kroil on the inside of the receiver on the barrel threads. Usually pretty quickly you'll see it make it's way through and they come off with much less effort than a Mauser barrel.

 

Cheers guys, there are plenty of things to try.
Soaking for a few more days, then I'll have another crack at it.

 

There is a flat on the bottom of the 1894 barrel near the receiver. Worst case scenario, pour or mold a bushing from epoxy bedding or JB Weld, and make sure you've got a firm grip with the barrel vise on that flat.

 

It may be unconventional, but as the flat isn't visible, and often the finish gets compromised, I have machined the flat larger.
That allows me to fit a large flat block on that side, and there is no problem holding the barrel.
But 24" of wrench is not enough!