What is shoulder bumping ??

H

Hank

Guest
I need help with this term, please.

Does bumping the shoulder mean actually pushing the shoulder backward, reducing the diameter of the case at the shoulder or both or neither???
 
It means to shorten the case length at the shoulder. Push back.

Any diameter change is simply the amount of resize done by the die. How far you push the shoulder back is set by how you set the die in the press.
 
So

some dies will push back only and some will push back and resize at the shoulder; correct??

I want to get a die to try to resize some used brass that came with a rifle. But, I don't know what die to buy.

I guess that if I get a die that only bumps the shoulder the brass may still be tight in the chamber. So I am thinking about a die that bumps and resizes all of which is controlled by how much the brass is pushed into the die....if I have that part right...
 
I would say that you need a full length sizing die. There are several options. Which one you choose will depend on your accuracy goals, and pocket book. There are one piece dies with expander balls, FL dies with interchangable neck bushings, with and without expander balls, and there are custom versions of all of the above. One can even use a combination of two dies to size the case. Bump dies do not reduce the diameter of the body of the case. I find little use for them. The amount of bump is dependent on how the die is adjusted in the reloading press. I set my FL dies to bump the shoulder back about .001 from the length of a case that has been fired until tight. One needs some sort of tool to measure this dimension.
 
Hank ...

Make life simple.

Redding Tech Talk ... Create A “Custom Die” With A Simple Shellholder Change!

To maximize case life and the accuracy potential of your reloads, it’s desirable to size fired cases the minimum amount that allows loaded cartridges to chamber freely.

Most hunters and many other shooters seeking smooth chambering reloads, full length size their cases each time. Since the interior dimensions of sizing dies are determined by the manufacturer, adjusting the shoulder setback is the only control a reloader has over how much a fired case is sized.

In the past, sizing die adjustment has been made through the trial and error method of rotating the die body in the reloading press. While acceptable results can be obtained using this method, precise adjustments are difficult at best.

Using this method, firm contact with the shellholder was not always possible. As a result, irregularities in brass hardness and thickness, as well as the uniformity and quantity of case lube affected shoulder setback. The resulting headspace variations created can adversely affect accuracy due to non-uniform primer/powder ignition. “Squaring” the die in the press is also precluded with this method of die adjustment.

To provide desirable shellholder-to-die contact during sizing, without excessively setting the case shoulder back, Redding now offers shellholders that are in increments of .002” thicker than the industry standard. The nominal thickness for industry standard shellholders is .125”. (See dimension X on the shellholder diagram. Go to first link below) Our new Competition Shellholder Set includes five shellholders that are thicker than this in increments of .002”. Therefore, the set includes shellholders that are marked +.002, +.004, +.006, +.008 and +.010, which is the amount the shellholder will decrease case to chamber headspace.

To select the proper shellholder for your particular firearm’s chamber, start with the shellholder marked +.010. The shellholder should be adjusted to make firm contact with the bottom of the sizing die during the case sizing operation. Resize a case and try it (unprimed and empty) in the chamber of your firearm. If the empty case does not chamber or chambers with difficulty, switch to the shellholder marked +.008 and repeat the process. Stop at the shellholder that allows the firearm’s action to close freely. Your cases are now being sized properly to fit your chamber with a minimum amount of headspace.

Here's two links for more info: http://www.redding-reloading.com/pages/compshellhldrs.html and http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=422114

Redding Shellholder Set #12 is for the 22PPC/6PPC/220 Russian etc. Just look up the Redding shellholder # you need for the caliber you're using. I just bought a second set from Midway for $37.59 plus $3.20 shipping using the U.S. Postal Service option. I only use the + .010 shellholder with my full length sizing die from day one with new brass. Unfortunately you have to buy a set, which may be good for some folks. Art
 
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Thanks to everyone

I believe I have enough information to order a F/L sizing die...in 6PPC.

But I use a Bonanza co-ax press so the shell holder are not an option..

I am just going to shoot for my enjoyment not competition..

I really appreciate all the replies..

Hank
 
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IMO their is no gain to be had by "touching the shellholder".

In other words, if you can get the bump you want by just screwing it in deeper or even grinding of the bottom of the die, do it.

You will not get more variation in bump than if you go to the bother of bottoming out the die.


al
 
More confused

I think understand what all of you have told me so far and I was thinking of the Redding neck sizing die which I assume can be adjusted to also bump the shoulder but I do not see it in 6PPC just 6PPC USA which I have read is a case with slightly different dimensions....

Will the Redding die work for 6PPC or is there another commercial choice??
 
Yes

I looked at them and they seem like a very good choice but I need to send them a couple fired cases and out of all the brass that came with the rifle only a few will chamber without sticking.....

And the gentleman who kindly included the brass for free with the rifle said it may not have all been fired in it....

So maybe I will find 3 or 4 cases that don't stick, load and fire them, and send them to Harrell's...that may be a good option for me since I don't anticipate loading for any other 6PPC in the near future and a chamber specific die would be fine...

Does that make sense or are there better options in the same price range ???
 
Bump die

A better question is: How to accurately measure the amount of bump or set back.
 
If you are shooting a 6mm PPC you don't want to use a traditional Full length size die ever. You will constantly upsett your neck fit and overwork the neck area.
Size and bump as required with a body die that does not touch the neck area at all.
Neck size with a seperate die say a bushing of correct diameter to do minimum sizing to reduce neck working and keep it all straight and get consistant neck tension. Works extra well with neck turned brass but does not size any of the body or bump the shoulder .
 
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Bump Back

Hank,
If you will call me at 803-477-1121 and I think I can help you out on the die.
Nick Loy
 
Problem Fixed

I ordered a die from Harrell's and used it today to size my brass and all is good....well at least as far as all of them being usable...(chambering instead of sticking)...

Nickloy sold me some Watson bullets and VihtaVuori powder at a "Christmas Gift" price which I appreciate...thanks Nick.

All of the information received here has been read and I thank those who replied...

Hank
 
You will receive,

......a bump gauge along with the die that Harrel will send to you!....Jan
 
So

that's what the little rascal is, thanks...I suppose I put it over the case and measure OAL, then bump/size, and then measure again...right???; close????
 
Sticky bolt..??

Went shooting today for the first time with my new, used rifle....

I used the Harrell's die to size the brass and and everything chambered OK...I had to use a .257 bushing to get the bullets to stay in place when seated...

So, first shot the bolt would not open completely upward...had to tap it with the plastic hammer about 1/8" of an inch to open and withdraw...

Out of the next 19 shots, over half had to have the hammer applied to the bolt...

I was using 27 gr of VihtaVuori and 65 gr Watson's and 66 gr Fowlers. I had about .010" of jam by my crude estimation.

I only fired 20 rounds and the Fowlers did better with the best group .190".

What is causing the sticking bolt???? should I bump more?? or what??

The sized cases are reading 1.543 in length using the gauge Harrell's provided and the die is touching the shell holder...

I have been out of this kind of shooting so long, I cannot remember all the symptoms and cures...

Edited: I did more searching here and read that my problem could be caused by old brass which I have...it came with the rifle and I have no idea on times fired....so I am going to contact one of the people who sell preped brass and get some new....its just not cost effective for me to buy the tools to do it...
 
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What you're experiencing is the "sticky bolt" which is the bugbear of the BR industry. It's the result of the BASE not being rsized enough, DON'T BUMP MORE :)

If the Harrell's sent you a die which doesn't offer the correct resizing they'll happily replace it, sometimes it becomes a matter of trial and error..... through no fault of theirs.

It's also possible that your chamber is simply too small.

Try new brass and see if it solves the problem.

al
 
6mmPPC case length

Hank-6mmPPC case length of 1.543" is WAY too long. Case mouths are being "jammed". 1.515" is a good length to trim to. If you get new Lapua .220 Russian brass,you'll find it approx. 1.515" before doing anything to it. For now,I would recommend trimming to 1.515"-even 1.500" would be ok. I think this will clear your "sticky" bolt situation. gpoldblue@yahoo.com
 
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