Sizing unfired Starline brass
Quote from EGGS on May 3, 2025, 11:56 pmI recently started reloading for a S&W 460 revolver, and several things have happened that has never happened to me before. Most notably is very dirty brass after the shot. I am using 46.2 grains of H110, ignited by a CCI 250 LRM primer behind a Hornady 240 Gr. XTP Mag. bullet, using a heavy roll crimp from Hornady crimp dies. Velocity average for 10 rounds is 1,924 fps. and SD of 22. Accuracy was acceptable for me. Nothing to really brag about, but acceptable.
My question to many other friends who reload was, why the very sooty, dirty brass? I even called Hodgdon and inquired there. The person I spoke to, suggested that it was because I either did not have enough pressure, or probably because the bullet was not held tight enough, long enough in the case to combust most of the powder inside the case. I am thinking that maybe my new Starline brass is not holding the bullet tight enough, and I am depending on the crimp to do all the work. If this is the case, should I need to size the brass as if it were once fired. I ran a couple cases through my Hornady Custom Die, and measured the difference between sized, and unsized. There is a .006 difference, with a .0015 longer case. This initial sizing of unfired brass seems unnecessary as it was to specs., .478.
What are your thoughts, seasoned reloaders, both about resizing new brass, and very dirty, sooty cases?
I recently started reloading for a S&W 460 revolver, and several things have happened that has never happened to me before. Most notably is very dirty brass after the shot. I am using 46.2 grains of H110, ignited by a CCI 250 LRM primer behind a Hornady 240 Gr. XTP Mag. bullet, using a heavy roll crimp from Hornady crimp dies. Velocity average for 10 rounds is 1,924 fps. and SD of 22. Accuracy was acceptable for me. Nothing to really brag about, but acceptable.
My question to many other friends who reload was, why the very sooty, dirty brass? I even called Hodgdon and inquired there. The person I spoke to, suggested that it was because I either did not have enough pressure, or probably because the bullet was not held tight enough, long enough in the case to combust most of the powder inside the case. I am thinking that maybe my new Starline brass is not holding the bullet tight enough, and I am depending on the crimp to do all the work. If this is the case, should I need to size the brass as if it were once fired. I ran a couple cases through my Hornady Custom Die, and measured the difference between sized, and unsized. There is a .006 difference, with a .0015 longer case. This initial sizing of unfired brass seems unnecessary as it was to specs., .478.
What are your thoughts, seasoned reloaders, both about resizing new brass, and very dirty, sooty cases?
Quote from The Human Manual on May 5, 2025, 3:41 pmIt is a good idea to size new brass, at least to ensure that case mouths are round. In your case, the carbon on the outside of the case indicates that the case mouth is not expanding enough to obturate the front of the chamber. Try sizing some cases before loading to see if that helps. A heavy roll crimp is recommended for the 460. As an aside, a 240 grain bullet is light for this cartridge. It is intended for heavier bullets.
It is a good idea to size new brass, at least to ensure that case mouths are round. In your case, the carbon on the outside of the case indicates that the case mouth is not expanding enough to obturate the front of the chamber. Try sizing some cases before loading to see if that helps. A heavy roll crimp is recommended for the 460. As an aside, a 240 grain bullet is light for this cartridge. It is intended for heavier bullets.
Quote from EGGS on May 6, 2025, 6:30 pmReally appreciate your reply. I had to look up the meaning of "obturate" though. If I understand it correctly it means to "close up". I can also understand that my cases must not of been holding the bullet tight enough to complete the combustion. What I do not understand about your reply is you say the case mouth must expand enough to "obturate"/"close up the front of the chamber". In this case are you referring to the cylinder hole? If this is the case, then my load is not generating enough pressure to "expand" the case mouth, is that possible when I am two (2) grains from MAX. in Hornady's book, and three one half (3.5) in Lyman's? Do I need to load heavier?
As far as using the 240 gr. I thought I was in a comfortable range above the 200 gr. many forums speak about that causes "flash cutting", and is also coming apart on deer when shot within 35-50 yds. Yesterday I loaded some Barnes 275 XPB, and am waiting for an opportunity to get out and try them. I am also considering getting some Swift A-Frame 265 gr. Would appreciate you input on these, if you have ever used them. I went ahead and resized 25 new cases, and also began using a Lee Factory Crimp die, after seating the bullets to the proper depth using the Hornady seating die, with crimping backed off. BTW, I forgot to mention that my first experience firing this revolver was using factory ammo, prior to getting dies. None of the brass showed any signs of being dirty, but sure had flattened primers.
Again, I am thankful for your expertise, and welcome any other advice you can give. Pray for peace.
Really appreciate your reply. I had to look up the meaning of "obturate" though. If I understand it correctly it means to "close up". I can also understand that my cases must not of been holding the bullet tight enough to complete the combustion. What I do not understand about your reply is you say the case mouth must expand enough to "obturate"/"close up the front of the chamber". In this case are you referring to the cylinder hole? If this is the case, then my load is not generating enough pressure to "expand" the case mouth, is that possible when I am two (2) grains from MAX. in Hornady's book, and three one half (3.5) in Lyman's? Do I need to load heavier?
As far as using the 240 gr. I thought I was in a comfortable range above the 200 gr. many forums speak about that causes "flash cutting", and is also coming apart on deer when shot within 35-50 yds. Yesterday I loaded some Barnes 275 XPB, and am waiting for an opportunity to get out and try them. I am also considering getting some Swift A-Frame 265 gr. Would appreciate you input on these, if you have ever used them. I went ahead and resized 25 new cases, and also began using a Lee Factory Crimp die, after seating the bullets to the proper depth using the Hornady seating die, with crimping backed off. BTW, I forgot to mention that my first experience firing this revolver was using factory ammo, prior to getting dies. None of the brass showed any signs of being dirty, but sure had flattened primers.
Again, I am thankful for your expertise, and welcome any other advice you can give. Pray for peace.
Quote from The Human Manual on May 7, 2025, 6:56 pmYou are correct in that your current powder charge is not at high enough pressure to expand the case neck enough to fully seal the front of the chamber. It could be that either a heavier powder charge or a heavier crimp would resolve this.
While I have not loaded either of the bullets you name, both are heavier, which takes up more capacity in the case, forcing the powder to burn more completely.
Please keep me posted on your results.
You are correct in that your current powder charge is not at high enough pressure to expand the case neck enough to fully seal the front of the chamber. It could be that either a heavier powder charge or a heavier crimp would resolve this.
While I have not loaded either of the bullets you name, both are heavier, which takes up more capacity in the case, forcing the powder to burn more completely.
Please keep me posted on your results.