shoulder bump 0.002 , case-chamber fit
- Thread starter walchi
- Start date
dgeesaman
Gold $$ Contributor
I agree the sizing is a bit more than I want when it’s a chamber cut with a specific reamer. Then it’s possible to get the body sizing down to .001 or .002. Going on memory, Tony Boyer uses .001 sizing on the body of his PPC cases.
For a factory chamber, or chambers cut from different reamers, getting that close might require different dies for each chamber. .004 might be the best you can do in that situation without having a new die made for each barrel.
For a factory chamber, or chambers cut from different reamers, getting that close might require different dies for each chamber. .004 might be the best you can do in that situation without having a new die made for each barrel.
thank you all for your opinion. so i was not that far off with with my feeling that the amount of play is a bit much. since my barrel is pressfit in the reciever and i am only loading for this one i have no problem with having a die for each barrel any soon 
one last question. in my situation with out buying a new or custom fit die, would it be better to dial the die back a bit to get less bump so the case gets centered via the shoulder due to the bolt pushing it more against the chamber? stiffer bolt would be the result but a less loose fit too.
one last question. in my situation with out buying a new or custom fit die, would it be better to dial the die back a bit to get less bump so the case gets centered via the shoulder due to the bolt pushing it more against the chamber? stiffer bolt would be the result but a less loose fit too.NorCalMikie
Gold $$ Contributor
Does you fired brass fit back in the chamber and bolt close WITHOUT resistance?
Neck size, reload and go shooting. ONLY full length resize when the brass starts getting snug in the chamber, then just enough so the bolt closes easy.
You full length resize and you're moving brass that doesn't need moving.
I shoulder bum/neck size and only full length resize when needed.
Got BR brass sized that way maybe 20/25 times with no issues.
Might do a body die size and reload.
Neck size, reload and go shooting. ONLY full length resize when the brass starts getting snug in the chamber, then just enough so the bolt closes easy.
You full length resize and you're moving brass that doesn't need moving.
I shoulder bum/neck size and only full length resize when needed.
Got BR brass sized that way maybe 20/25 times with no issues.
Might do a body die size and reload.
Here's my input on this never-ending story based on my experience.
1. There is nothing wrong with neck sizing if you are willing to accept that at some point your reloaded rounds won't chamber or is creating excess wear of the bolt lugs. Or you don't mind chamber checking each time after you load detect chambering issues - a tedious exercise for sure. If you're strictly a recreational shooter this is a plausible approach, I guess but not one I'd choose.
2. I neck sized for many years, often getting several loadings before chambering became an issue. Why did I neck size? Two reasons, I believed that full sizing reduces case life, and you could achieve better accuracy by neck sizing. At least that's what the "experts" claimed in the late 60's and 70's. I now believe both of those assertions are myths.
So why would I change to full sizing 100% of the time. Because I'm primarily a varmint hunter and I wanted 100% functionality in the field without having to verify the chambering of each round before going afield. And I met some bench rest guys who shot tiny groups that convinced me that proper full sizing will not reduce case life and will not degrade accuracy. Then then taught me how to properly full-size cases.
3. So, several years ago, at my age it's hard to remember when but it's been a long time, I switched to full sizing BUT learned how to do it properly. This means using a bump gauge to compare fired case head space with sized case head space and adjusting my die so that the shoulder is slightly pushed back about. .001 to .002". I can attest to their claim that if done properly, full sizing does not reduce case life or result in degrading accuracy. I base this claim on loading and shooting thousands of rounds. When I get a case failure is almost always in the neck area. Accuracy wise, I can detect no differences at least at my level of precision which is in the 1/2 moa range.
4. Because full sizing also sizes the radial dimension of the case, this aids in chambering also.
Bottom Line: I choose the full size with a minimal shoulder bump because it produced 100% functional ammo and does not reduce case life or degrade accuracy, at least in my experience. If a round won't chamber it ain't any good to me.
1. There is nothing wrong with neck sizing if you are willing to accept that at some point your reloaded rounds won't chamber or is creating excess wear of the bolt lugs. Or you don't mind chamber checking each time after you load detect chambering issues - a tedious exercise for sure. If you're strictly a recreational shooter this is a plausible approach, I guess but not one I'd choose.
2. I neck sized for many years, often getting several loadings before chambering became an issue. Why did I neck size? Two reasons, I believed that full sizing reduces case life, and you could achieve better accuracy by neck sizing. At least that's what the "experts" claimed in the late 60's and 70's. I now believe both of those assertions are myths.
So why would I change to full sizing 100% of the time. Because I'm primarily a varmint hunter and I wanted 100% functionality in the field without having to verify the chambering of each round before going afield. And I met some bench rest guys who shot tiny groups that convinced me that proper full sizing will not reduce case life and will not degrade accuracy. Then then taught me how to properly full-size cases.
3. So, several years ago, at my age it's hard to remember when but it's been a long time, I switched to full sizing BUT learned how to do it properly. This means using a bump gauge to compare fired case head space with sized case head space and adjusting my die so that the shoulder is slightly pushed back about. .001 to .002". I can attest to their claim that if done properly, full sizing does not reduce case life or result in degrading accuracy. I base this claim on loading and shooting thousands of rounds. When I get a case failure is almost always in the neck area. Accuracy wise, I can detect no differences at least at my level of precision which is in the 1/2 moa range.
4. Because full sizing also sizes the radial dimension of the case, this aids in chambering also.
Bottom Line: I choose the full size with a minimal shoulder bump because it produced 100% functional ammo and does not reduce case life or degrade accuracy, at least in my experience. If a round won't chamber it ain't any good to me.
Deleted member fkimble@charter.net
When the firing pin hits the primer it pushes the whole round forward til either the case taper or the case shoulder taper stops forward motion The case taper or the shoulder taper will center the round in the chamber. With a factory chamber you will have a slight clearance. A custom chamber cut to minimum will always be a little tighter than factory. Chamber a full length sized round, shake the gun sideways and front to back. Is there any sound to indicate the round is loose in the closed chamber?
Frank
Frank
Coyotefurharvester
Silver $$ Contributor
I don't think I could feel 0.002 movement of the cartridge in the chamber, in the receiver. You would have to cast the chamber to really know it's dimensions.
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