Printing ABS with a PTFE thermal end

sorry if this has been posted elsewhere, i cant seem to find any info about the problem i am having.

I have been trying to build a tech-zone Mendel for a while and after all the rest of the problems handled. I have one problem that constantly causes more headache. I built the thermal hot end with a PTFE barrel and brass nozzle, i set the machine to 220c and after a few minutes the PTFE barrel spit out the brass nozzle, I'm printing ABS and i know that PTFE does some nasty things at 250c, but my question is: can a PTFE thermal break be used for printing ABS or does it get too soft at the high end of its temp scale? or is the tech-zone oak block/ peek barrel tube the only option for this temperature? I wanted to ask the community before i set out to buy more parts to rebuild my failed hot end.
also: does anyone know of a place that sells PEEK barrels pre milled, I dont have access to milling tools, and the only supplier I can find only has the raw blanks.

thank you for any support i can get, and once again sorry if this thread is misplaced or a dupe.

You can use PTFE, but it has to be very well constrained and cannot be used as a load-bearing component. As you have seen, it will get soft when heated and doesn't hold its shape on its own.

If you look at an MK4 extruder on a makerbot, you'll see that they use a washer and nut on the barrel. They then use two bolts to hold the washer. All of this is done to support the barrel when trying to push filament through it. The nut bears the load rather than the PTFE threads, which will strip out when the barrel is heated.

Also, you have to clamp around the PTFE with hose clamps, copper tube, or some similar support structure. The idea behind doing this is that it stops the PTFE from bulging outwards and creating leaks. If it expands radially, plastic will start seeping in between the threads and you'll soon have a giant plug of plastic on top of your heater.

Hybrid insulators (PEEK outer layer and threaded section with a PTFE sealing insert at the core) are another popular way of supporting the hot end.