I was trying a new load for my 4 inch .357 M520. I went out with a batch of handloads to try out. I leaded up the barrel in just ten rounds which, was the ten rounds that I used to chrono the load. I was trying out the following load.
Winchester case
Winchester SPM primers (unique's website listed mag primers for this load)
Hunter's Supply 158 gr. Hard cast bullets
6.3 gr. unique.
I was getting around 1150 fps with this load. After shooting the string I checked the barrel and noticed a good amount of leading in the barrel. These bullets are supposed to be rated to 1600 fps without gas checks. My crimp is a little on the heavy side with the pimers flattened. Extraction wasnt's too difficult. What can I change? Do I need gas checks, lighter crimp, non-mag primers or go to a 158 JSP which, are just about as cheap as the hard cast bullets I'm using?
Thanks, Flip.
Winchester case
Winchester SPM primers (unique's website listed mag primers for this load)
Hunter's Supply 158 gr. Hard cast bullets
6.3 gr. unique.
I was getting around 1150 fps with this load. After shooting the string I checked the barrel and noticed a good amount of leading in the barrel. These bullets are supposed to be rated to 1600 fps without gas checks. My crimp is a little on the heavy side with the pimers flattened. Extraction wasnt's too difficult. What can I change? Do I need gas checks, lighter crimp, non-mag primers or go to a 158 JSP which, are just about as cheap as the hard cast bullets I'm using?
Thanks, Flip.