FL sizing shoulder bump question

Bingoc

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Well I see I am going to have to break this down Barney style and I am not the one showing his utter ignorance of precision reloading. You obviously do not understand tolerance stacking and SAAMI specs. You are going to have to put your thinking cap on here. It just so happened that Hornady has a nice video that you might want to watch and follow along to see how to actually do it correctly for precision.

BTW, 30 years LR competition experience, to include state champion, ranked nationally at 1k and have shot a 6" five shot group in mile match with 300 WSM and designed and loaded all kind of wildcats from custom 6 BR to 338/408. I understand precision reloading to be sure. I have been using custom shoulder stub guages made with my reamers for 30 years. And no must precision shooters are using custom/Whidden or Redding dies set up to allow precision bump with or without cam over.

To make it clear lets look at the 6.5 creedmoor to help understand the issue. SAAMI specs give a +- of .010 on the shoulder specs for this cartridge. Others can be as low as .007. In other words IF your chamber is absolutely within SAAMI dimension there can be a .010 shoulder variance from one gun to the other. Ammo has to minimal SAAMI at max dimensions so it will fit ANY gun. Add a worn die reamer and you could add another .002 variance. Did the mftr or gunsmith run the chambering reamer in .002 too long? That is why basic die instructions are written for the novice and are set up for cam over to get back to factory SAAMI specs. Their lawyers make them set the instructions up that way.

Now let's say you take a sizing die and set it down on the shellholder (again you must assume that they are all the correct height but I have seen .008 variance). I have an RCBS rockchucker and I do not care if you are Magilla Gorilla once metal meets metal that is all the compression and shoulder bump you are going to get. Period!!!!! Now IF you are lucky and IF you can actually measure shoulder bump you might be within .002 of the chamber shoulder. You could also in actuality be about .008 or more off. Again, think about it, that is why Redding has the competition shellholders that offer .0010 of adjustments in .002 increments for the guys hung up on shoulder bump or has dies that are a shade too long for correct bump. Keep reloading that same case time after time at that distance and you will eventually get case head separation. Think about this, how is it even possible to get case head separation IF cam over works perfect every time?

There is a reason the top two factory die mftrs (Whidden and Redding) give specific instructions for adjusting the dies for optimal shoulder bump and max case life to back off 1/3-1/2 turn and work your way down. On most dies 1/8 turn is about .009 of actual movement on the shoulder. As for Hornady dies, you might not know it but they actually have competition shooting teams that compete long range and do well with their dies. So not crap dies.

Just to put it to bed finally, we already had the Whidden instructions posted (BTW John Widden is world class champion and LR shooter so pretty sure he knows what he is talking about) and here is a composite of the Redding die instructions.

Cam over is for returning back to factory specs and the novice. Period
Thanks for the Redding Die Instructions. I will give it a try.
 

tim_w

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Mar 25, 2008
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538
No blame really meant to anyone. And I apologize to everyone as I posted that in frustration.
 

tim_w

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Mar 25, 2008
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If you use a standard die and holder I think what was said about it being a generic safetey setup by nanf is correct.

As we have tools like the redding comp shell holder sets and shims we can get the benefits of consistent sizing pressure and distance consistency with all the adjustibilty we need for precision tolerances and results.

I think stating absolutes in most cases is a bad habit as its almost never true.

I believe this is what was trying to be coveyed.
 

BountyHunter

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Look everyone, it is most important to understand that we are dealing with many variables to include lawyers from companies that are concerned about liability not accuracy. Too many people do not understand that, read the simple die instructions and take it as gospel as the best way to adjust dies for precision. Cam over will get you back to factory specs no questions 99.9% of the time. Though it is not uncommon to run into a die that is a shade too long and needs .015-.020 taken off the bottom. However, for precision, controlled headspace and case life you need to very accurately measure headspace and adjust your die down accordingly, not up. Hard to measure how much up you need to go. If you back the die off and have to come down to cam over, no harm no foul. However, if you automatically go to cam over and do not really understand and measure your headspace then you run into issues. That is exactly why IMO the top two die mftrs (Whidden and Redding) tell you to do it that way. Another reason to always measure every shellholder for height. I buy shellholders and put them in each die box and ONLY use that shell holder with that die set. That way my settings and measurements never can change. IF you have two guns of the same caliber, use mentioned Skip Otto Die Shims ($15) are your friend. Set your dies up for the shortest case and then add shims for the longer case. Pretty easy to do too.
 
Last edited:

ButterBean

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Whats the deal with people being so pugnacious in this thread It just sours the whole thing. Reminds me way too much of....well....never mind. But its sure will have a negative effect on activity of the forum. Serious buzz kill.
Once again, if I was out of line I apologize to all
 

SammySTW

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Look everyone, it is most important to understand that we are dealing with many variables to include lawyers from companies that are concerned about liability not accuracy. Too many people do not understand that, read the simple die instructions and take it as gospel as the best way to adjust dies for precision. Cam over will get you back to factory specs no questions 99.9% of the time. Though it is not uncommon to run into a die that is a shade too long and needs .015-.020 taken off the bottom. However, for precision, controlled headspace and case life you need to very accurately measure headspace and adjust your die down accordingly, not up. Hard to measure how much up you need to go. If you back the die off and have to come down to cam over, no harm no foul. However, if you automatically go to cam over and do not really understand and measure your headspace then you run into issues. That is exactly why IMO the top two die mftrs (Whidden and Redding) tell you to do it that way. Another reason to always measure every shellholder for height. I buy shellholders and put them in each die box and ONLY use that shell holder with that die set. That way my settings and measurements never can change. IF you have two guns of the same caliber, use mentioned Skip Otto Die Shims ($15) are your friend. Set your dies up for the shortest case and then add shims for the longer case. Pretty easy to do too.
In this case for me, setting the die to cam over pushed the brass very far below factory specs. But I guess that's because the whidden dies are not supposed to be set to cam over, where the rcbs dies I have are supposed to be set to cam over to get factory spec.
 

BountyHunter

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In this case for me, setting the die to cam over pushed the brass very far below factory specs. But I guess that's because the whidden dies are not supposed to be set to cam over, where the rcbs dies I have are supposed to be set to cam over to get factory spec.
Yes, but remember, factory specs are normally way under where your shoulder is. That is fine for a couple reloads and if brass is not problem. drop them in any gun and will normally chamber.
 

SammySTW

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Yes, but remember, factory specs are normally way under where your shoulder is. That is fine for a couple reloads and if brass is not problem. drop them in any gun and will normally chamber.
Yes I understand that, I think you misunderstood what I was saying about your comment
 

BountyHunter

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Yes I understand that, I think you misunderstood what I was saying about your comment
Gotcha. I have seen short dies push the shoulders far enough back the shoulder case junction pushes out just enough that it will not chamber. If that happens back the die off and resize to get the junction back in but the shoulder will still be too far back until you fire the case sgain.
 

7stw

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Whats the deal with people being so pugnacious in this thread It just sours the whole thing. Reminds me way too much of....well....never mind. But its sure will have a negative effect on activity of the forum. Serious buzz kill.
Tim, I am right there with you, and I know whom, or what you said "never mind" to. I've been on this site going on eleven years, love the threads, the experiences, and the friendships, that go on outside of the website.
Life is too short! As Jerry Springer said, oh well, you know! Take care Tim!
Good words spoken!
 

7stw

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I didn't expect this thread to turn into a debate. I just asked a simple question and got simple answers, so thanks to yall for the help. I'm just here to learn new things and try to help someone else if I can. I've mostly used RCBS sizing dies up until this one, and I've always followed the directions to set them up with a little cam over and it has seemed to work fine. But I'm constantly learning, and starting to play with measuring shoulder bump and learning how that works with the FL dies. Thanks for the wisdom everyone
And most of the time, it dosent become a debate, or anything like that. There is some awesome people here willing to share techniques, and experiences, without a bunch of hoopla! That's what we are all here for, and I'm sure it's why we joined to begin with! We all need to keep this a great thing!
Nuff said!
 

7stw

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I have primarily been a hunter for some 45 years and have reloaded many calibers but I don't spend a lot of time shooting paper. I doubt that any of my guns have 300 rounds down the pipe. I use an RCBS Rockchucker press and RCBS full length sizing die sets. I have always full length sized the brass, as I did not want to have any additional effort closing the bolt. Therefore, I have only gotten about three reloads before they have to be discarded, especially from the belted magnums, i.e., the 264, 300 Wea., 338 WM etc. As soon as I get that little tell tail frost ring above the belt, I know that the crack has started. I have cut the cases longitudinally to verify the beginning of a crack.
After reading the posts on sizing brass for a number of years, I invested in the Sinclair Bump Gauge instruments and had a good dial caliper and tried to bump the shoulder 0.002 of a 300 Wea. using the RCBS full length die. I adjusted the die to meet the shell holder with no cam over, just gravity and backed it off one turn. Moved the sizing die down to meet the case and completed the stroke with a little resistance. I backed the sizing die up and measured the case. No difference. Moved the die an 1/8 turn and repeated the process and got more resistance. Measured the case and got about 0.001 in. bump. Then I cleaned the case and tried to chamber it, but found that it would not chamber without more pressure than I wanted to apply. I re-lubed the case and moved the sizing die about a 1/16 turn and tried again. I got about 0.003 in. bump, but the case would not chamber. I tried this again after another 1/16 turn and got about 0.004 in. bump, but the case would not chamber. So I got frustrated and went back to my full length sizing routine and insured that the case would chamber. but that reflected a bump of about 0.009 in.
I would sure appreciate and advice on what I am doing wrong. Thanks in advance.
Bing, I had that problem once, and I believe that I ended up replacing my dies, when I should have taken them to a machine shop, and have material removed from base.
Die was too long, or high, and it had allowed , through a couple if firings, the brass to grow taller then chamber would allow, to fit, without resistance. New brass is in order, as well, because if you push it back, you'll create another problem. The feared Bulge!
I used to smoke my shoulders, on ONCE fired brass, and adjust die, to just kiss the soot, on the shoulder, and that usually always worked.
 

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