measuring chambers
- Thread starter scott_r
- Start date
burnt_servo
CGN Ultra frequent flyer
- Location
- right in the middle of b.c.
I try to avoid pushing the shoulders back , if anything I like to only resized 2/3's to 3/4's of the neck , leaving the shoulder untouched .
I measure mine with the Forster datum tool it's great for the belted case brass life and can't hurt the accuracy also . Also got into using the lee collet die , only have too full size after 4 reloads again setting die by the case measured with Forster
Hi Scott,
I've learned a lot from posts here and Mystic Precision on this subject. I now body size when needed and neck size with the lee collet die. I have never full length sized cartridges, just kept the factory ammo shot in our rifles. I too use the Hornady Headspace comparator kit to measure when the cartridge develops noticeable resistance to bolt close.
I measured that as one point, the difficult to close bolt cartridges...then using the Redding body die, turned it in until I could measure a difference in shoulder set back using the comparator. I use a difference of .002 from the first point as shoulder set back and then proved it in the rifles we have. The .002 shoulder bump feels great! The first time setting up to achieve this was interesting because there was a point on my press where nothing would happen to the cartridge and then about a 20 degree turn sized the shoulder back .002. ( I have since learned the reason for that thanks to others here.)
Mystic's tip was to apply a piece of masking tape (around .004 thk) to the base of a shoulder bumped cartridge and then cycle it in the rifle. The bolt should be difficult to close and in some cases not close at all, proving the point that a person has a close fitting cartridge to the chamber. .002 shoulder setback, from other posts here, seemed to be acceptable for our applications on this end which was good for hunting applications and not too far set back to work the cartridge more than necessary. The taped cartridge is now the "go, no-go" guage to set up the process for shoulder set back and comparator is used to sample every once and while...just to audit the shoulder bump process.
This works for us on this end instead of full length resizing.
Hope this helps and I would surf around here for posts. Lots of good info.
Things you should know about our situation here
- bolt actions - 7mm-08 Savage
- hunting application
- have not gotten into annealing yet, to further the life of the brass, and annealing has an effect of how readily shoulder bump back occurs
- I am a sophomore reloader, but am willing to share what's worked for us.
Regards
Ron
I've learned a lot from posts here and Mystic Precision on this subject. I now body size when needed and neck size with the lee collet die. I have never full length sized cartridges, just kept the factory ammo shot in our rifles. I too use the Hornady Headspace comparator kit to measure when the cartridge develops noticeable resistance to bolt close.
I measured that as one point, the difficult to close bolt cartridges...then using the Redding body die, turned it in until I could measure a difference in shoulder set back using the comparator. I use a difference of .002 from the first point as shoulder set back and then proved it in the rifles we have. The .002 shoulder bump feels great! The first time setting up to achieve this was interesting because there was a point on my press where nothing would happen to the cartridge and then about a 20 degree turn sized the shoulder back .002. ( I have since learned the reason for that thanks to others here.)
Mystic's tip was to apply a piece of masking tape (around .004 thk) to the base of a shoulder bumped cartridge and then cycle it in the rifle. The bolt should be difficult to close and in some cases not close at all, proving the point that a person has a close fitting cartridge to the chamber. .002 shoulder setback, from other posts here, seemed to be acceptable for our applications on this end which was good for hunting applications and not too far set back to work the cartridge more than necessary. The taped cartridge is now the "go, no-go" guage to set up the process for shoulder set back and comparator is used to sample every once and while...just to audit the shoulder bump process.
This works for us on this end instead of full length resizing.
Hope this helps and I would surf around here for posts. Lots of good info.
Things you should know about our situation here
- bolt actions - 7mm-08 Savage
- hunting application
- have not gotten into annealing yet, to further the life of the brass, and annealing has an effect of how readily shoulder bump back occurs
- I am a sophomore reloader, but am willing to share what's worked for us.
Regards
Ron
Last edited:
hometownhero
CGN Ultra frequent flyer
- Location
- Toon Town, Sk
I have been doing it for years. I push the shoulder back about .02 where as if you set up the die like the instructions that come with it say you push it back .08 or more I have found. Some of my dies have a big (in reloading terms big) gap between the shell holder and the bottom of the die.
Below a Colt 5.56 Field gauge at 1.4736
Below the field gauge in my adjusted Hornady case gauge
Below a fired case from my AR15 carbine, remember there is brass spring back meaning the case is slightly shorter than chamber headspace.
Below the same case after full length resizing and .003 shoulder bump.
Below on the left is a +.004 Redding competition shell holder that pushes the case into the die .004 "LESS" than the standard RCBS shell holder on the right. The +.004 shell holder is what I used to get .003 shoulder bump with the die making hard contact with the shell holder and press cam over. If I had used the RCBS shell holder and set up the same way the shoulder would have been pushed back .007 and over resized.
With the die making hard contact with the shell holder any slop in the press is removed and the case shoulder location will be more uniform when sized.
Your dies are adjustable up and down and can be adjusted for a custom fit to "YOUR" chamber. Meaning a few thousandths below the red dotted line below.
Below the field gauge in my adjusted Hornady case gauge
Below a fired case from my AR15 carbine, remember there is brass spring back meaning the case is slightly shorter than chamber headspace.
Below the same case after full length resizing and .003 shoulder bump.
Below on the left is a +.004 Redding competition shell holder that pushes the case into the die .004 "LESS" than the standard RCBS shell holder on the right. The +.004 shell holder is what I used to get .003 shoulder bump with the die making hard contact with the shell holder and press cam over. If I had used the RCBS shell holder and set up the same way the shoulder would have been pushed back .007 and over resized.
With the die making hard contact with the shell holder any slop in the press is removed and the case shoulder location will be more uniform when sized.
Your dies are adjustable up and down and can be adjusted for a custom fit to "YOUR" chamber. Meaning a few thousandths below the red dotted line below.
I use the Redding competition shell holders. Once you start using those you will quickly see how big of a joke cranking 1-14" threads on a springy press, with springy brass is. You don't have to measure anything, and can use the same dies on multiple rifles without adjusting them. Between extra dies and measuring tools you don't need, not having the Competition She'll holders is costing you money .
