Author Topic: Basic question (Read 582 times)

Doctor Sam · « **on:** September 09, 2003, 07:27:11 AM »

I read in the RCBS 1st edition cast bullet manual that cast bullets should not be seated deeper in the case than the length of the case neck. A similar note here regarding what happens to a gas check in that situation was discussed.

What is the reason for this? I understand that pressure will be increased but it should still go out the path of least resistance, i.e., the bore.

I have bullet molds in two calibers that cast very long bullets and a lot of lube rings are going to be "naked".

You guys educate me. What are the consequences of deeper seating?
Thanks.
Doctor Sam

John Traveler · « **Reply #1 on:** September 09, 2003, 08:36:50 AM »

Hi, doctor Sam!

That's a good question!

1. Seating a cast lead bullet deeper than the neck exposes grease grooves and grease to the powder charge. Not good. Possible contamination.

2. Seating a gas-checked bullet deeper than the neck GREATLY increases the chance of the gas check coming loose and forming a bore obstruction. Also not good. A loose gas check usually causes "ringing" of the bore, ruining it.

HTH
John

Doctor Sam · « **Reply #2 on:** September 12, 2003, 06:54:09 PM »

Thanks, John. I understand. This then begs the question: How many lube grooves need to have lube in them? One of these long bullets (8mm) has four and the 6.5 has three. Not counting the last one on the nose for crimping if crimping is done.

They would get pretty nasty in my coat pocket. Have to keep them in a box.

Doctor Sam

Cat Whisperer · « **Reply #3 on:** September 13, 2003, 02:03:33 AM »

One finds out how many lube grooves NEED to be lubricated by experimenting. It's a function of velocity, alloy and lubricant. Some low velocity boolets only require ONE groove to be lubricated. Check both accuracy and leading when you build your set of experiments.

John Traveler · « **Reply #4 on:** September 13, 2003, 02:34:54 AM »

Cat Whisperer is correct. Experiment to find optimum number of grease grooves to be filled.

The American Rifleman Technical Advisor documented that for some loads (.38 WC and .45 ACP SWC target loads), OVER LUBRICATION and reduced accuracy can occur. Most lube-sizers can have die and punch adjusted to control the number of grooves filled with grease. I always go with the minimum needed for best accuracy and NO barrel leading. Saves refilling grease reservoir time.

John