56-56 Extraction Problem

[Bead Swinger]

Hi All -
'Took my 56-56 rifle out to my second cowboy match today, and while she was a lot of fun  - I wound up jamming the rifle three times on extraction.
In each instance, the jam was with a Buffalo Arms cut-down 50-70 case, not one of my hand-filed 50-70's.

Has anyone else had this experience? 
Not having measured the diameters of all of the cases, the only really obvious differences in the cases are as follows:

The Buffalo Arms 56-56 cases are based on Starline 50-70 brass, and have been cut down, and had the back rim  (rear face) of the case beveled.  The ones I did by hand  are based on DGW 50-70 cases have the rims rounded, (not beveled), and both the front and the rear face of rim are rounded, not just the rear face.

Ideas of what to look for are welcome - Unjamming the cases was difficult, and left a rough edge on the extractor blade.  Should I replace the blade? (S&S Firearmes, here I come).

Thanks.  Beadswinger

[Arizona Trooper]

Most 50-70 cases have a rim diameter of about 0.67", while Spencers are a lot happier with 0.64" to 0.65". Rounding the rims may not be enough, you might need to reduce diameter a bit. Also, A lot of original Spencers have been dry fired way too much. This will put a dent in the back of the chamber on the right side where the firing pin batters it. Chambering often is not effected, but when you actually fire a round, the case will expand enough to hang up. You can remove the dent with a 1/4 round needle file and the problem will go away. By your serial number, you have one of the 2000 rifles made for the state of Mass. Have fun with it!

[mtmarfield]

   Greetings!

   What was the nature of the jam? If your extractor blade skipped past the cartridge rim, it may indicate that the StarLine rim is a mite too small in diameter and/or the chamber is fouled. If the chamber is fouled, you may {if you haven't} want to anneal your brass to effect a better seal. Is your DGW brass annealed/softer? As long as the rims are small enough to feed through the magazine, clear the receiver cut, and chamber properly, I wouldn't worry about rim diameter. Too small a rim may afford the cartridge too much play, allowing the extractor blade to sqeeze past... Especially if the brass is in a fouled chamber.

   Hope This Helps! & Be Well!

                     M.T.Marfield
                       10-22-06