Shoulder Bumping & Neck Sizing

[kvd]

If you seat the bullet into the lands you could be causing high pressure spikes. If you are loading hot and jamming the bullets into the lands you are most assuredly running pressures well above the maximum for the round and possibly the rifle.

Seating -0.020 off lands but I have been loading 195 grain Berger EOL's and 180 grain Berger Hybrids in my 7 RSAUM pretty hot. I've been annealing after every firing. May try every other firing for the annealing operation. Thank you for the response SheepDog.

Ken

 

[kvd]

Actually it may not. A body die gives you the same sizing that a bushing FL die would without a bushing in place. One thing that you might want to check out is whether there is any gap between the plates that function as a shell holder on your press and the bottom of your body die when a case that is being sized is in the die at its highest position. I have not checked this on a Forster press but on a Rock Chucker you can adjust a die to touch the shell holder with no case in place, and then with one in place, in the process of being sized there will be a slight gap, because of material stretch in the press linkage. In the instance where I discovered this, the gap was about .006, which effectively gave me some room for further adjustment. Don't take this too far because beyond the point where it eliminates the gap, all that happens is that excessive stress is put on the press.

Appreciate the additional comment BoydAllen. Elaborating further on my efforts to resize my 7 RSAUM brass in the Redding body die - after doing all I felt comfortable doing with the Co-Ax press without bending something, I put the die in a single stage press and adjusted the die down to just touching a Lee No 5 shell holder. The case still was not making contact with the shoulder of the body die. Next I tried a Redding No 6 shell holder - still - no joy. My hope is that the Redding bushing full length sizing die will be shorter than the body die and allow shoulder contact before it is bottomed out on the shell holder plates of the Co-Ax press. Are you or do you know of anyone using this set up for shortening the case a few thousandths?

Ken

 

[BoydAllen]

One thing that I mention a lot is that fellows seem to want to bump back from a shoulder to head dimension that is not maxed out, sometimes even from a single firing of a new case. We bump to create clearance when we need it. It usually takes a few firings for the head to shoulder dimension to reach its maximum. If you do find that you need to bring the die shoulder lower in the press (closer to the surface of the shell holder that the case head touches) the easiest way is to shorten the shell holder, by removing some material from its top. You can do this on a lathe, but lacking that, a flat surface and some 320 wet and dry will do, just turn the holder after each stroke across the paper, and measure as you go to keep things as parallel as you can. With some chambers and some dies, the problem is not the shoulder but the diameters of the chamber body and die body. If this is your problem you can take a lot off of a shell holder only to discover that your bolt close is still not what you are looking for. What are your diameters, sized and unsized at the shoulder, and just above the extractor groove where the sizing of the die stops? If these are not being reduced by sizing, you will need another die. Some manufacturer's dies are smaller than others, or you can order a custom FL die. Hopefully your die is reducing the diameter of the body of the case along it entire length.

 

[LHSmith]

In order for a brass case to have drag when it is removed from the chamber the pressure has to be high enough to expand the chamber more than the brass can spring back. This can be exacerbated with soft or over-annealed brass because soft brass has less spring.

Not to be a contrarian, but my opinion based on reloading for both SR BR and varmint hunting experience differ from the above statement. IMO it is brass that has become work-hardened by repeated firing without FL resizing every time that causes bolt function difficulty on beginning of extraction. Over-annealed brass does not have any inherent energy while work-hardened brass DOES continue to build up energy -i.e. it eventually resists sizing attempts because it has lost it's memory to do so. I used to neck size varmint rounds and informal target rounds and have always found it necessary to eventually FL size to eliminate extraction problems. This was with moderate loads and before my practice of routine annealing and ran the gambit of a multitude of bolt rifles in many calibers. IIRC, before Lapua brass which kept competition load pressures much lower than they are today, there was a practice of some SR BR shooters that used cases with annealed necks to the dead soft region and simply "soft" seated the bullets with zero neck tension. They had no problems in chambering or extraction using neck sizer only dies. This was back in the days when the only dies commonly available for BR were generic Wilson neck sizers that were called upon to fit a plethora of non-standard SAAMI match chambers.
From Ratigan's book "Extreme Rifle Accuracy" -"You should not wait until the cases get tight before getting out the full length die. If the cases are allowed to work harden at the larger size they will not want to go back to the smaller size and will need to be replaced. In order to get the most life out of your brass you need to be proactive about the full length sizing process."
For Ratigan's process to work you need a FL die that is a relatively close match to your chamber. Without this "match," accuracy and brass life will never optimum.
Having said the above, if you are getting satisfactory accuracy and brass life by NS only .....by all means continue that process. All I am saying is NS never worked for me for my accuracy demands.

 

[fguffey]

Are you or do you know of anyone using this set up for shortening the case a few thousandths?

Lee #5 and Redding #6: If I was sizing a case and was curious if I would gain anything by using different brands I would measure. All of my shell holders have a deck height of .125", if the deck height is .125" that is it; with exceptions. My favorite shell holder is the RCBS shell holder. RCBS shell holders fit like a hand-me down shirt, it fits only where it touches. Rather than change shell holders I raise the deck of the shell holder, meaning I reduce the deck height of the shell holder by adding shims between the deck of the shell holder and case head. I am able to reduce the deck height of the RCBS shell holder by at least .010".

I know, that is so confusing but reducing the deck height increases the ability of the shell holder to reduce the length of the case from the shoulder to the case head. It was not that many years ago reloaders ground the top of the shell holder or bottom of the die; it was never necessary to grind the shell holder or bottom of the die. If I ever decided to grind on my tools I would first want to know how much grinding/material removal was necessary. Adding the shims between the deck of the shell holder and case head increases the presses' ability to overcome the cases' ability to resist sizing.

I have a tool that is design to precision grind, I do not use it to grind shell holders and dies but if I ever found it necessary I have 2 of them JIC.

Bad thing? I have shell holders that fit and have little to no room for a shim between the deck of the shell holder and case head. I also find those shell holders useful.

F. Guffey

 

[kvd]

If you do find that you need to bring the die shoulder lower in the press (closer to the surface of the shell holder that the case head touches) the easiest way is to shorten the shell holder, by removing some material from its top. You can do this on a lathe, but lacking that, a flat surface and some 320 wet and dry will do, just turn the holder after each stroke across the paper, and measure as you go to keep things as parallel as you can.

Isn't it odd the one can buy Competition Shell Holders with will lengthen the distance between the base of the shell holder and the die body when all that is required is to back out the die but one can not find (or at least I haven't found) shell holder that will shorten the distance between the shell holder base and the die body. I noticed Bullets.com has RCBS shell holders on closeout for $4.33 each. May be a good time to pick up a few to modify. Thanks for the response.

Ken

 

[fguffey]

I have arbor presses that have been modified to size cases, I no longer use them for that purposes but when using one of them I never considered the cases ability to whip the press, if the case refused to be sized/swaged it collapsed, crushed or was turned into a case with bellows. If your press refused to size the case consider the press; there is a possibility the case has more resistance to sizing than your press can overcome.

F. Guffey

 

[kvd]

Rather than change shell holders I raise the deck of the shell holder, meaning I reduce the deck height of the shell holder by adding shims between the deck of the shell holder and case head. I am able to reduce the deck height of the RCBS shell holder by at least .010".

fguffey,
Not confusing at all - I see where you are coming from. Thank you for the tip.

Ken

 

[fguffey]

Isn't it odd the one can buy Competition Shell Holders with will lengthen the distance between the base of the shell holder and the die body when all that is required is to back out the die but one can not find (or at least I haven't found) shell holder that will shorten the distance between the shell holder base and the die body.

Strange? I am the only reloader that sizes/forms cases for short chambers. All that I have ever found necessary for sizing cases for short chambers is a feeler rage. When I cut a chamber I start by forming short cases, to keep me from starting over the next day I save the short cases. I have no problem starting with a long gage to accomplish the same task, as the old saying goes, check the length of the chamber often; I want to know the length of the chamber in thousandths.

F. Guffey