Fire forming new brass

[King Medallion]

I have 100 new Jamison 45-75 brass cases, my new-to-me rifle has the larger Uberti chamber. Do I have to do anything special to fire form or will using a regular load do the trick? I've loaded up a box with 24.0 gr. of 5744 to start with. Rifle arrives tomorrow.

[Sir Charles deMouton-Black]

That sounds like a perfect case-forming load. It can also help you get familiar with your rifle and sight it in.  When reloading, just neck size.

[larryo_1]

I must toss in my 25 bits worth here.  when I first got my '6, I noted that it has the larger chamber.  When I fire-formed my brass, I used 17 grains of Bullseye and then filled the case with cornmeal ( out of Ma's stash) and topped that off with a Beeswax plug.  Stepped out of the Shop door and went bang.  Then I had to trim the brass a bit and other than that--that was the way I did a whole bunch of brass from WWW-348's to Bertram and to Jamison.  Never had any problems.  There are most likely other ways to do this but this is how I did it.

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[Sir Charles deMouton-Black]

I have used separate fireforming loads, but only when I need to blow out a tapered neck, like .30-30 to .38-55 or .30-40 Krag to .375 Flanged Nitro Express.  If the purpose is to effect a fairly minor change, why waste the primers, powder and time spent stuffing wadding over the powder?

I load for my Brno 304 7 x57R combination gun. I have RWS cases for full bore loads, but like to have cast bullet small game loads in my pocket. For these I use .303 Brit cases. I run them through a 7 X57 die to bring the neck to size and load them. They are a bit skinny for the first shot but blow out considerably upon firing. The next reload is with a fully formed case. Either way, the results are exactly the same.

[dusty texian]

I have 100 new Jamison 45-75 brass cases, my new-to-me rifle has the larger Uberti chamber. Do I have to do anything special to fire form or will using a regular load do the trick? I've loaded up a box with 24.0 gr. of 5744 to start with. Rifle arrives tomorrow.

Congrats on getting you a 76  45/75  , King Medallion! Cant help you with the load , you know I'm a charcoal burner .Look forward to hearing how your new rifle shoots and seeing a pic. ,,,,,,,DT

[Silver_Rings]

When I got my Chappy 76 in 45-75, I didn't think it would have the Italian (large) chamber.  So I just loaded up a bunch of different smokeless loads and shot them.  Found out after firing that the cases had expanded.  I would just load regular loads and have fun shooting the.

Comment on the larger chamber.  This chamber results in a shorter neck on the case.  I find the 300 grn. gas check bullets I got from Lead Heads barely fit in the neck so they do not intrude into the powder area of the case.  I have read that having lead bullets protrude in to the powder area of a case is bad for accuracy.  My 400 grn. loads seem to bear this out.  I could not neck size my fired cases with my Lee 45-75 dies with out setting the shoulder back some, so I ordered Lee's custom neck size die.  Problem with that is after neck sizing with the Lee custom die, when I seat the gas check 300 grn. bullet, the bullet will slide in and out of the case.  Not enough neck tension.  Called Lee and they recommend annealing the cases.  Have not tried this yet.

Silver Rings