I hope someone here is able to help me.  The problem I am having is with a Thompson Center Contender.  It is a stainless from not the Armor Alloy.   I have been using it with a blued 7mm TCU barrel and all has been good.    I recently bought a used blued barrel in 22 Hornet.   I put the new to me Hornet barrel on my frame and it locked on and would not open.  To get the barrel off the frame I had to disassemble the entire working mechanism which was a precarious pain with the several tiny springs that could easily get lost.  I now have the barrel off the frame and the frame re-assembled.  I am guessing the problem is with the locking lug on the barrel.  It is a solid one piece not the split type. It appears to protrude out slightly farther that does the 7mm TCU barrel that gives no problems.  I have an idea that the fix might be to replace the solid lug with a split lug. Does that sound about right ?  Is there a way to modify the current solid lug to get it to work ?  I can also see that the small divot at the rear center of the lug is noticeably smaller in the offending barrel than in the trouble free barrel.  Is that something that needs to be addressed ?  Sure would appreciate some helpful advice on this issue. If I can do something to fix it for free it will get done much sooner than if there is cost involved. If I know what I need maybe I still have time to drop hints to Santa !

That is what I was thinking the answer would be. I found them at EAB co. but $60.00 plus shipping will have to wait for next years budget.

Excellent! At one time many years ago, TC would change out locking lugs on early barrels for free. Those days are sadly gone though. I’m glad you were able to work out a solution

In this situation even with the hinge pin removed from the frame the barrel would not release from the frame. There was simply not enough clearance for the lug to pass once it locked in.
Dissembling the frame was the only way I could figure out to get to the lug and compress its spring enough that the lug could pass and the barrel open. The lug was just too long maybe by only a few thousandths but that was enough to hang it up.
Disassembly is not too complicated but there are three tiny springs in there that can easily be lost if not paying close attention. Loosing parts tends to complicate the repair and adds expense. This time I got lucky and the only cost was about an hour of my labor which must be pretty cheap because my wife says I am worthless.  If she is right then I fixed it for free.