I'm a newbie. I just started casting in order to make cheap, low powered practice loads for my 416 Rigby and 470 nitro.
I cast a bunch of 416's using the 350gr RCBS mould, and lubed and sized them with a .417 RCBS die. I'm using wheel weight material.
Started loading some 5744 practice rounds MV should be around 2000fps. I measured one of my bullets with a digital caliper as an after thought. It measures 0.419.
Do I have a problem?

I dunno, not to sound funny, but are you sure it was a sized bullet, and not "as dropped" from the mold?

What happens when you run that same bullet back through the sizer die? do you get the same measurement?

Oh, and are you measuring around the base, the crimp area, or the body of the bullet? I suggest measure each place on the bullet, and rotate the bullet and measure again, to see if the bullet is out of round.

All good thoughts. I know they are all sized, as lubing and gas checks go on in the same operation on my press.
I went downstairs to try your other suggested measurements. I also measured a couple of Barnes banded solids that are on my bench. I suspect an instrumentation problem. Those machined .416 cal bullets measured .418 cal.
Assuming those CNC machined bullets are .416, my cast bullets from a .417 die measuring a couple thousandths over spec is consistant.

I don't see a problem if your barrel groove diameter is smaller then your cast bullet diameter by at least .001 to .002. Also you can shoot the fattest bullet that your chamber neck area will let the brass expand and let go of. If it won't let the case neck expand you can get dangerously high pressures. One quick way to find out is take a fired case (don't resize it) and try one of your cast and sized bullet for fit. It should slip in easy. If it's tight you are in trouble to try to shoot them that way. Have you miked you barrels groove diameter yet?

I can slide them into a fired case, not quite as loose as a 416 cal Barnes solid. Since the sizer says 417, this seems reasonable? Basically, there is slight resistance, but I can manually insert them fairly easily. THe commercial 416's essentially fall in.
The 417 sizing die, by the way, was the only available unit I could find for this bullet.

I'm a bit hesitant to take my steel calipers to the inside of my muzzle for fear of damaging the crown area.

quote:

Originally posted by Marty:
I can slide them into a fired case, not quite as loose as a 416 cal Barnes solid. Since the sizer says 417, this seems reasonable? Basically, there is slight resistance, but I can manually insert them fairly easily. THe commercial 416's essentially fall in.
The 417 sizing die, by the way, was the only available unit I could find for this bullet.

I'm a bit hesitant to take my steel calipers to the inside of my muzzle for fear of damaging the crown area.

IF they are loose then you're safe in that area.

You need to tap a soft lead cylinder that is just slightly larger then the groove of your barrel into the muzzle and one into the breech. Then measure they with a micrometer unless you have a pretty accurate pair of calipers. There are many ways to slug the bore and I'm not going to get into here and I only generalized on the above. The reason for miking both ends is to find out if the breech end is smaller then the muzzle because that's not conductive to accurate cast shooting. Don't feel that your rifle barrel may be that way just alerting you to things to look out for.

Measure bullets with a micrometer. Before dial calipers were common we used vernier calipers.
A common nick name was "very nears" because they were not really considered a precision tool in the sense of a mike.