Brass won't chamber

[2flasargent]

I' posted a while back about the acquisition of a 65 Spencer and received great information.  I"ve since purchased the plastic blanks and they work well with my centerfire block.   The person who had the weapon before me fired hundreds of cut down and crimped Kapritchek cartridges in it.  I wanted to live fire and bought 10 of the starline brass from Track of the Wolf but they refuse to chamber.  they go in about a quarter inch and no further.  While I don't have dies at this time to try resizing, this seems like much too far off to ever work.  Attached are the dimensions of the respective rounds.  I'd have to guess the chamber is badly built up from the kapritchek rounds, but tried to brush the tar out of it with a brass brush and bore cleaner w/o any noticeable change.  Barrel serial number matches the breach, and what I can see of the chamber looks smooth.  Bore is tolerable with good rifling.  Am I missing something here?  Thanks for all advice.  This is a great site.  (picture too big)
                 Dia. at Base     Dia at top
Kopratchk    .539              .511
Plastic blank .548              .522
Brass           .557              .535

Respects to all, Stay safe

[Arizona Trooper]

If it was dry fired a lot, the rimfire firing pin can put quite a dent in the right side of the chamber, which will cause the problem you are having.

[Garret]

Good Day,
I found myself in a similar situation a couple of years ago trying Starline in a Sporting Rifle built with an original receiver and new barrel chambered to the original 56-50 specs.  The problem is that this brass is made to fit the reproduction Spencers and will not chamber in any originals.  After some searching I found that Buffalo Arms offers brass altered for Spencer that's made from .50-70 brass.  The mouth of the case is relieved internally back a bit to allow seating your bullet.  I ordered up some and they work just fine!
It was also pointed out to me that whatever dies you get, make sure they're for original chambering, not the repro!  You'll also need to experiment with bullet diameters, because if too large, they'll bind in your chamber and you'll feel like you were back with the Starline brass issue!

Good luck with your Spencer!  They're really fun to shoot. 
Continue safe and well,
Garret

[2flasargent]

Humble apologies for not responding sooner.  Life gets in the way of hobbies sometimes.  I had checked the chamber for any distortion on the edge w/o finding anything obvious.  Garret's response seems to be spot on, and I'm only out the 10 rounds I got from Track of the Wolf.  I'll investigate Buffalo Arms for brass.  Fortunately the plastic blanks chamber and cycle well, and most of what I'll be doing is reenacting cavalry.  ( under the fervent prayer that the events are allowed to happen again).  Sincere appreciation for the feedback.   

[2flasargent]

Out of stock at Buffalo arms currently.