Misfires & Problemswith 45-70 marlin 1895

This afternoon, I shoot about 20 rounds with 5744 30 grains
and had two misfires with federal large rifle primers. I rechambered thede rounds and they fired properly. I did notice some unburned powder in my rifle barrel.
I have using the RCBS priming unit that fits on my Rock Chucker with a primer tube feed.
Now i am beging to question the powder 5744 , partial fill,
priming technique,bullet crimping( used the Lee crimp).
Also, I got some erratic velocities on my Pact chronograph.
The volicities ranged from 1270 feet per second to 680 feet per second.
I have used the same chronograph before with consistant velocities. I shoot several rounds with my 375 H7H mag
whic seemed to be consistant.
I called Accurate powder company on Friday.They assured me that 5744 would perform properly with a partil filled cartridge.
The rounds printed well on a 50 yard target.Its just that I got some misfires, unburned powder, and eratic velocities.
Comments or answers will be appreciated.