Anyone have a secret formula to free up a rusted screw. I've been applying auto transmission fluid to an old martini breechblock for 3 weeks and no shift. I even tried gently heating the thing then pouring on the ATF but still won't budge.

Going to try Lanotec HD-15 next.

I wouldn't bother with this one except the receiver has the clearest markings VR 1880 Mk1. The external surfaces are excellent but the guts must have been dipped in brine at some time.

Yesterday I found a MH 577/450 that is all pitted externally BUT has a great bore, $150 with 1885 bayonet(no scabbard). The owner was going to hand it in during the gun amnesty starting June 30.

Have you tried some penitrene (sp?)Comes in a little yellow bottle.

second the penetrenne(sp) Bunnings don't sell it you may have to go to a bearing or bolt supply.
You could also try tapping quite firmly the screw, like as in hitting the end of the screwdriver, you could also then try hitting and twisting at the same time although a proper impact driver is best for this. Impact driver is a relatively cheap item you can usually buy at auto parts joint.
You could also try asking this Q over on the gunsmithing forum.

diesel fuel is the best penetrant I have come across. put it in a tin of fuel & leave it for a week. If you dont mind damaging the screw head an impact screwdriver is a big help but make sure the driver fits well

An old dude that I know who referbishes old engines says that either Brake Fluid or real Iodine works quite well. Up and over here I use a product called "Fluid Film", contains teflon and bubbles and froths as it works to lift off the rust and dirt. derf

I'd go for brake fluid too , soak it for a while - like days - then impact driver and a little heat on the surrounding area , but just a little .

For really stuck screws ,I use 1/2 brake fluid and 1/2 brake cleaner,then if need be,I use a square shanked screwdriver and small wrench.Dip the screwdriver tip in valve grinding compound and it will not slip out of the slot.Valve grinding compound works well with Phillip's head
screws also.

WC

Ballistol, and Kroil

Aleko

BAW,
The thread may have an adhesive on it (like lok-tite). Use an electric soldering iron applied to the head of the screw, put a finger on the metal beside the screw so you can tell if it's getting too hot. Works even if there isn't lok tite on the thread.

The valve grinding paste on the tip of the screw driver is an excellent idea.

nothing unsticks rusted metal parts like coca cola


cheers