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bumping shoulder
#6237202
03/26/16 02:21 PM
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Joined: Feb 2013
Posts: 1,389
BassCat'99
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I've read where this has been refereed to and am wondering where is a good source to learning the method?
22 Creedmoor
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Re: bumping shoulder
[Re: BassCat'99]
#6237255
03/26/16 03:31 PM
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Joined: Nov 2007
Posts: 9,502
RiverRider
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You can buy body dies which only work the case shoulder and which are to be used with a neck sizing die. You can also use a FL die only. With either approach, it comes down to very, very careful adjustment in terms of how far you turn the die into its threads on the press. You can measure the shoulder of a fire-formed case and adjust the die based on that, or with the FL die you can work by feel---if you're dealing with a bolt action.
Adjusting the die is a tedious process. Turning it in 5 degrees pushes the shoulder 0.001 inch. Five degrees is less than a single tic of the second hand on a clock.
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: bumping shoulder
[Re: BassCat'99]
#6237256
03/26/16 03:31 PM
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Joined: Jan 2012
Posts: 9,273
blackcoal
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The Greatest Enemy of knowledge is not ignorance, it is the illusion of knowledge.--Stephen Hawking
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Re: bumping shoulder
[Re: blackcoal]
#6237276
03/26/16 04:02 PM
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Joined: Nov 2007
Posts: 9,502
RiverRider
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Yes, this explains it well.
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: bumping shoulder
[Re: BassCat'99]
#6237292
03/26/16 04:32 PM
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Joined: Jan 2012
Posts: 9,273
blackcoal
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watching the opening 8 seconds of the Easter egg hunts this weekend is another good example.
The Greatest Enemy of knowledge is not ignorance, it is the illusion of knowledge.--Stephen Hawking
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Re: bumping shoulder
[Re: BassCat'99]
#6237305
03/26/16 04:55 PM
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Joined: Dec 2008
Posts: 41,083
J.G.
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I just use an FL die, and do what River Rider explained.
Get a Hornady Head space gauge and use the proper insert for your cartridge. It is labeled on the back of the package. I'll measure five pieces of brass just to see if they don't all match, they almost always do.
Raise the ram with a piece of fired brass in the shell holder, screw in the FL die, until I can't screw no more. Lower the ram, turn the die a quarter turn, size the brass. Measure head space. It hasn't contacted yet, turn the die a quarter turn, size the brass. You will feel when you're making contact with the shoulder. The handle of the press will can over. Then the tedious size, measure head space, adjust the die process begins. Work on it, until you can size a piece of brass and you have shortened the distance from the case head to the shoulder by .002" It takes a while, but it's worth it.
When all is said and done I put timing marks, with a Sharpie, on the die threads, on the lock ring, and when I had a press I can to screw the die into, I'd put a timing mark on the press. So you end up with three different marks that should line up. That way when you've taken the die out of the press to work on something else, and you're re-installing you can put the die right back where it was when you found the proper bump.
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Re: bumping shoulder
[Re: BassCat'99]
#6237307
03/26/16 05:02 PM
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Joined: Feb 2013
Posts: 1,389
BassCat'99
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thanks guys, I'll be working 308 and 6.5CM. Is it necessary for 223 that's in a gas gun?
22 Creedmoor
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Re: bumping shoulder
[Re: BassCat'99]
#6237311
03/26/16 05:09 PM
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Joined: Dec 2008
Posts: 41,083
J.G.
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I have done the same process for .308 gas gun. But .003" or .004" is acceptable. I want to make sure it chambers and ejects. And gas guns get very dirty!
I plan to do the same thing for .223 gas gun.
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Re: bumping shoulder
[Re: BassCat'99]
#6237403
03/26/16 07:13 PM
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Joined: Jan 2009
Posts: 19,165
Judd
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.223 gas gun I'd use/buy small base dies to make sure you get a good base resize.
Don't let your ears hear what your eyes didn't see, and don't let your mouth say what your heart doesn't feel
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Re: bumping shoulder
[Re: BassCat'99]
#6237489
03/26/16 09:47 PM
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Joined: Nov 2007
Posts: 9,502
RiverRider
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I've used conventional .223 dies for a number of ARs I've owned and never had an issue. I would use SB dies if necessary, but only if I had to. No point in working your brass any more than necessary.
"Arguing with you always makes me thirsty." -Augustus McRae
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Re: bumping shoulder
[Re: BassCat'99]
#6237538
03/26/16 11:05 PM
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Joined: Feb 2013
Posts: 1,389
BassCat'99
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I have 4 AR's left and have not had a problem with them using Lee FL dies.
22 Creedmoor
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Re: bumping shoulder
[Re: BassCat'99]
#6237604
03/27/16 12:31 AM
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Joined: Jan 2012
Posts: 9,273
blackcoal
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Most likely you will not have a problem, but in the event you should have a tight chamber in the future the SB dies are available.
The Greatest Enemy of knowledge is not ignorance, it is the illusion of knowledge.--Stephen Hawking
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Re: bumping shoulder
[Re: BassCat'99]
#6248824
04/05/16 07:29 PM
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Joined: Apr 2015
Posts: 610
JTPinTX
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River Rider and JG gave good advice on using the Hornady guage and proper set up of the die. I usually set my die on precision rifles to bump right at .002, or a hair under. I think .003 to .004 is a better number for an AR.
Another thing I can say is die shims can be useful for making small adjustments when needed. You can put them between the die lock ring and the press to make quick or temporary adjustments without messing with the die setting. Shims cut from a coke can will be 3.5 thousandths. I have some I ordered from McMaster-Carr that are .002 thick. I use the .002 shims all the time. Shims can also be handy if you load for 2 different rifles chambered for the same cartridge. I have 2 7x57 Mausers, and one needs a different die adjustment by .003". In that case I set the die for the shorter one, and when sizing brass for the longer one I just put a coke can shim under the lock ring. Works like a charm.
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Re: bumping shoulder
[Re: BassCat'99]
#6250022
04/06/16 06:30 PM
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Joined: Oct 2004
Posts: 39,481
redchevy
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I would like to see test results showing normal FL sized and then with the shoulder bumped and see differences in the groups and velocities.(say take 20 new brass load and fire then take 10 and load with normal FL size and 10 and load with the shoulder bumped .002 and compare what you get out of the second and so on firings, not just comparing multiple fired cases with bump to factory new never fired.)
I load for a few guns of the same caliber and use the same set of dies so I don't bump shoulders.
It's hell eatin em live
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Re: bumping shoulder
[Re: redchevy]
#6250066
04/06/16 07:21 PM
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Joined: Sep 2009
Posts: 18,907
ChadTRG42
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I would like to see test results showing normal FL sized and then with the shoulder bumped and see differences in the groups and velocities.(say take 20 new brass load and fire then take 10 and load with normal FL size and 10 and load with the shoulder bumped .002 and compare what you get out of the second and so on firings, not just comparing multiple fired cases with bump to factory new never fired.)
I load for a few guns of the same caliber and use the same set of dies so I don't bump shoulders. Accuracy would be good for either method with a tuned load for that method. The idea of bumping the shoulder back a small amount, about .002" to .003", is to prolong case life. It doesn't over work the web area, where the case head will separate. In my 300 WM and previous 260 Rem, I would wear out the case by either the primer pocket too loose or the case web from case head separation. I had brass in different groups with different firings and some sized with a bump and some with a FL size. The FL sized cases definitely wore out faster at the case web area, especially for the 300 WM. There are times when a FL size is needed. But most shooters can do well with a bump. The problem is bumping the shoulder is a more advanced way of reloading, and some shooters do not do it correctly and cause chambering problems. To keep it simple, a FL size is best.
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