Bumping sholders
- Thread starter Oldboy55
- Start date
Probably too much bump, but if you been doing it for that long and are satisfied with how long your brass lasts, carry on the way you have been.
I check "bump" by adding layers of scotch or masking tape to an unfired cartridge case head until the bolt won't close. The setting that gave easy bolt closure is the proper size dimension. If you can remove firing pin spring from bolt it has a more pronounced effect on bolt closure effort. The "plus" side to doing it this way vs. the generic method explained in reload manuals is longer brass life. Also note the reload manuals differ in their method- some say "until s/h touches ram" while others say "touch plus 1/8 turn".
No matter the maker or brand of dies used, that a person buys for reloading. I often wonder, with so many questions asked about how to use/adjust them, show up on the various sites, does anyone read the instructions that come with the dies and what the maker advises on how to set up and adjust the dies for proper use and results ?
Yes Ive read the instructions from RCBS and follow them to a tee. Just was wondering if that was giving me more bump than necessary.
Those instructions are notoriously generic, the only way to know for sure is to measure base to a datum line before and after sizing.
L.Sherm
Silver $$ Contributor
You might as well throw the instructions in the garbage, you can have zero to .010 following those instructions, take jfranks advice.
I've got 2 Redding dies that bump zero touching the shell holder and camping over.
Last edited:
Think I might just do that. Thanks
Bob in WI
Silver $$ Contributor
I use a setup like this for everything I reload whether target rifles or hunting.
Caliper base and shoulder stub. Very precise measurements to bump of about .002 . Most times that's all I need for easy feeding and bolt closing.
Attachments
Dimner
I do believe in Captain Crunch.
I have found that the amount of shoulder bump is proportional to how much I have to trim when I reload. When I bump and it measures just 0.002 shoulder bump from fire formed brass, I always have the trim the very least. Even get away with a few firings before I need to trim.
rwj
Gold $$ Contributor
Do the instructions inform the user how to ensure that the case body is not limiting chambering? If no, and you keep lowering the die, it is easy to create excessive headspace.
Coyotefurharvester
Silver $$ Contributor
OB55 are you reloading for hunting, informal targets, plinking? Bolt gun, gas gun, break action? Cartridge?
Bill Norris
Back in the Day
The correct amount of shoulder bump for a given rifle is important no doubt due to not over-sizing the brass. BUT, if the shoulders are not bumped enough in some cases the hard bolt close will produce vertical in groups. I've seen this more than once. I don't think we should get wrapped around the axle of the .002 bump being standard. I am not claiming it will take more than .002 in every rifle. That's why it is critical to measure and test if needed.
okie
Silver $$ Contributor
maybe, maybe not. measure it like shown below
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