Got over to the range to shoot my brother's Stevens 414 Armory, High Wall musket and Winchester 1890 .22 short yesterday. Had the 1890 barrel lined for him as a B'day gift and it shoots great. With original iron sights was easy to hold 2-3" group @ 50yd. 

The High Wall also shoots very accurately, but the chamber needs some help as was necessary to use needle-nose pliers to remove the casing. Extractor/ejector works fine, but the chamber does not want to let go of the case. Likely needs some brushing with Kroil to get it 'slicked up'.

The 414 was a really pleasant surprise. Very straight shooter and wonderful action and trigger. It is in the best overall condition with 98-99% finish. And, that trigger........... zero creep, breaks like glass and pull is under a pound. Ejector/extractor works perfectly. Think I'm going to have to find one to build as my next .22 single-shot. I was highly impressed.

Have you checked the fired cases that will not extract
easily from the Highwall to see if they indicate a ringed chamber?
That ring can cause them to form to the chamber and
not want to come back out after firing.

Keep on hav'n fun!
MikeT

Yep, Brownell's tool is called a "chamber iron"

SSShooter wrote on Dec 6^th, 2011 at 8:16pm:

What actually happens is that the shorts fired in a long rifle chamber will gas cut the chamber wall at the case mouth if the barrel is one of the typically soft steel early (or cheap) ones used on many rimfire rifles.  It's essentially the same situation that happens with a .357 Magnum with a lot of shooting with .38 Special ammo.   

David