School me on bumping shoulders + trimming question

[TheGerman]

I think I've 'graduated' to do this now, but have some questions.

I know that after you fire your round the brass will conform to the length/size of your chamber which can be measured with a set of calipers and a correctly sized comparator insert to measure the headspace.

My question here is twofold; first, does the brass give a correct size measurement after the first firing, or would you need to fire the brass multiple times? Secondly, I have Redding Type S bushing dies; how in the world do I set them up to bump the shoulder .003 back? This is less than the thickness of a sheet of paper, whats the trick here?

I've also read a few things about the length to trim your brass to and the more I read, the more confused I get. I used to simply trim new brass back to the minimum length to keep everything uniform, but I am slowly under the impression that I am trimming too much off right from the get go. Let's say that I get brand new brass and the max is 2.015 and the 'trim to' length is 2.005 (308 Win reference). Let's say the new brass is 2.022 when you get it; what do you trim it to and why?

Thanks again.

 

[ChadTRG42]

Re: School me on bumping shoulders + trimming question

The brass will expand to your chamber size on the first firing. To neck size and bump the shoulder at the same time, you have to run a FL neck bushing die. If you have a body die and a neck only die, then you will have to size in 2 steps. You can measure how much you bump the shoulder back by measuring the datum point on the case shoulder. You will need the proper guage to measure the datum point, like an RCBS precision mic, or Hornady comparator (or similar). .002"-.003" shoulder bump is fine. Once you set up your die, lock it down, and you can always come back to that setting.

New brass should not need to be trimmer. When brass does need to be trimmed, trim it to minimum (2.005") or .015"-.020" short of your max chamber case length. The max length is normally longer than 2.015".

 

[Red Ryder]

Re: School me on bumping shoulders + trimming question

There are all manner of complications to this question.

Forster and both have told me that optimally, we want to bump the shoulders of the cases so that that the shoulders are only .001 - .002 smaller than the chamber. What you do is take a case fired in your rifle and then use a bump gauge (bought mine at Sinclair) to measure it. Then you use the resizing die to reform the brass to a tolerance .001 - .002.

Caution must be used in this process however because when bumping you're altering the dimensions of the case which in turn, can alter the pressure generated, which in turn...can alter your face.

I don't know where you got that .003 number. EVERYplace I've looked it says .001 - .002 MAXIMUM.

If the resizing die doesn't bump enough, I've been told that I could send my Forster die into the factory along with 3 -5 fired cases and that they would remove a few thousandths off the bottom of the die. In this manner, it allows the case to be rammed into the resizing die JUST a little bit more thus bumping the shoulder.

 

[LRS_Ranger]

Re: School me on bumping shoulders + trimming question

Are you trying to bump it with a neck sizer only, or is it a full length die with the neck bushing? I'll be waiting for some answers on this myself...

 

[bkster]

Re: School me on bumping shoulders + trimming question

try to find someone who knows how to reload to show you the difference
i could show you how to do this is a few minutes
but reading about it will take longer to understand

to bump the shoulder you will need the equipment first
and an understanding of what your doing
then trial and error to get what you want
good luck

 

[Casey Simpson]

Re: School me on bumping shoulders + trimming question

German, do what Chad said and ignore the others

 

[memo43]

Re: School me on bumping shoulders + trimming question

bkster. How about a video on doing this
I'm pretty sure others might find it usesful

memo

 

[427Cobra]

Re: School me on bumping shoulders + trimming question

Your gonna need a set of dial calipers

This Tool will show you waht your Headspace is and how much your full length die is bumping the shoulder
http://www.midwayusa.com/viewProduct/default.aspx?productNumber=479704

This tool will tell you exactly what your trim length is
http://www.sinclairintl.com/.aspx/pid=32925/Product/Sinclair_Chamber_Length_Gage

 

[vman]

Re: School me on bumping shoulders + trimming question

Im with chad and cobra.

I own the Hornady tools and I think they are great. I recomend them.

I also fire my new brass twice before I find its at a useable length. Its only a small difference but the difference between first firing and second, i feel is significant.

Once my cases become slightly resistant to chamber, it is at that point that i want to bump back.

I try to find that point at which closing the bolt is easy, and closing it is slightly harder, is only 0.001" bump. Then i know im doing minimal resizing.

 

[TheGerman]

Re: School me on bumping shoulders + trimming question

The .003 bump measurement idea I got from the tutorial thread in this forum. I may just go .002 after what I am reading.

I understand what you guys are saying about the Hornady tools and ordered them; I already had some of them like the comparator body for measuring bullets.

Now here is where I am still confused:

When screwing my FL sizing die into my press I have always followed the directions supplied with the dies as to how to set them up. Shellplate up, screw the die down until you feel it touch the shellplate and then screw another 1/8 or 1/4 of a turn further. Now how do you get a consistent bump from something that isn't set up with precision? If I put my die in, unscrewed it and then repeated the process as best I could, I am sure I would be off by at least a few thousandths every time. So how are you guys doing this, and making sure to not 'over bump' when you start sizing your first piece of brass?

I am sure I am missing something here.

 

[ChadTRG42]

Re: School me on bumping shoulders + trimming question

At first, it will be trial and error. With the press ram all the way up, you will have to insert your die just above the shell holder, maybe an 1/8" or so less. Measure a fired case for a datum reference point on the shoulder, then size it. If the shoulder doesn't decrease by your desired amount, then slightly lower the die down, size it again, and remeasure. Do this until you get the .002" shoulder bump. Once you get the measurement where you want it, lock the ring down on the die, and your die will be set to bump it back .002" every time. And make sure the sized brass chambers smoothly into your rifle. If you're not sure, just FL size it and call it good. It's less head ache this way. I stopped messing with all the fancy prep and just FL size everything and go shoot. It makes it much easier!!

 

[TheGerman]

Re: School me on bumping shoulders + trimming question

Trust me, I thought of that too. I just want to see if it will make a difference.

So, do you FL size everything all the time, or is there a time you just neck size; and why?

 

[vman]

Re: School me on bumping shoulders + trimming question

I only use an FL sizer, but i have set the FL sizer die up so that it bumps back 0.001.

Once i have it all sorted I lock the lock ring on the die, and its always going to be at that setting.

My understanding is that body dimensions should be the same on all cases with this method.

Neck sizing will require you to use a body sizing die at some point in time.

 

[Notso]

Re: School me on bumping shoulders + trimming question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TheGerman</div><div class="ubbcode-body">
Secondly, I have Redding Type S bushing dies; how in the world do I set them up to bump the shoulder .003 back? This is less than the thickness of a sheet of paper, whats the trick here?

Thanks again. </div></div>
To answer your question above, read this and follow it verbatim:
Reloading 101

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Setting up the dies:

In the absence of a headspace gauge (which actually pretty worthless if you think about it, since they are made to a standard that may or may not match your chamber) or another device that allows you to measure the shoulder of the case, you will need the rifle that the ammo is intended for. For this text the brass we are resizing will not fit into your chamber. That gives you a starting point: The bolt won’t close.

How To:

Put the die into your press and raise the ram with a shell holder in place. Screw the die down until it hit’s the shell holder. Now back it off 1 full revolution. Size a piece of brass. Attempt to chamber the brass. Does the bolt close smoothly with NO resistance? If it does you’ll need to back off the die some more and try more brass until it DOES NOT chamber with out resistance. Remember to keep the brass lubricated during this phase. Once you are feeling resistance or can’t get the bolt closed, begin rotating the die clockwise about a 1/16th or a 1/8th of a turn at a time and resize the case again. Continue to check the brass against your chamber and reset the die as needed until you get to the point where it just closes smoothly and without resistance in the rifle. Don’t forget to keep the case lubed while doing this!! Now take a new piece of brass and resize it. It may fit your chamber cleanly but chances are you will need to give the die another 1/16th of a turn to ensure the first time through the die gets it right, even brass coming out of dies has spring back. At this point in time you have your dies set and are probably pushing the shoulder of the case back .001 - .002”, not a whole lot of work on the brass. Lock your dies in place and don’t touch them again.</div></div>

I followed this advice and its worked perfectly for me without a headspace gauge.

 

[ChadTRG42]

Re: School me on bumping shoulders + trimming question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TheGerman</div><div class="ubbcode-body">So, do you FL size everything all the time, or is there a time you just neck size; and why? </div></div>
I FL size all but 1 caliber. I neck size my 300WM brass for my personal gun to help extend brass life. Everything else gets a FL sizing. It's much easier to load for.

 

[Fisky]

Re: School me on bumping shoulders + trimming question

I FL size all the time.....But loading the same loads for 2 different guns may have more to do with that than anything. That, and I like to keep it simple.

 

[Leaddog]

Re: School me on bumping shoulders + trimming question

A shoulder bump of .001 is plenty. In fact, it's perfect.

 

[samnev]

Re: School me on bumping shoulders + trimming question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ChadTRG42</div><div class="ubbcode-body">At first, it will be trial and error. With the press ram all the way up, you will have to insert your die just above the shell holder, maybe an 1/8" or so less. Measure a fired case for a datum reference point on the shoulder, then size it. If the shoulder doesn't decrease by your desired amount, then slightly lower the die down, size it again, and remeasure. Do this until you get the .002" shoulder bump. Once you get the measurement where you want it, lock the ring down on the die, and your die will be set to bump it back .002" every time. And make sure the sized brass chambers smoothly into your rifle. If you're not sure, just FL size it and call it good. It's less head ache this way. I stopped messing with all the fancy prep and just FL size everything and go shoot. It makes it much easier!! </div></div>
+1 on that

 

[sniperaviator]

Re: School me on bumping shoulders + trimming question

Hornady makes a "Match Grade" neck bushing die that "bumps the shoulders" without full length resizing. You can read about how it works at the below website. Click on the Reviews:
http://www.midwayusa.com/viewproduct/?productnumber=389298

Looking at a cross section of the die in the Hornady catalog, I'm not sure if the shoulder bump is adjustable. It may be adjustable by screwing in the die more or less. Here is a die specifically made for bumping the shoulders without full length body resizing.

 

[Blue Streak]

Re: School me on bumping shoulders + trimming question

I've been confussed on this issue as well.

I have been neck sizing only,..to the point that my bolt is hard to close then I FL size and trim if needed.

I tried to "bump" the shoulder once my bolt was hard to close and found that my regular hornady die would not work to just "bump".

I did a little research and found a few articles that stated some FL dies will simply not "bump".

I'm about to the point to simply give up the "bump" idea and simple FL size once the "fired" brass exibits to much force to close the bolt.

 

[Graham]

Re: School me on bumping shoulders + trimming question

Chad knows.

I will add that measuring shoulder bump with a proper tool is essential. Mass-produced dies are a crapshoot: I have had some dies that, when screwed all the way down in the press until the die touches the shellholder, don't touch the shoulder of the case. I never grind the die base. I take a new shellholder, cut about 10 thou off of it, and start the measuring again. I then use that shellholder with that die from then on.

There's nothing wrong with bumping the shoulder .003 - .005, but you will be working the brass more, with associated case life and wall-thickness issues.

 

[Blue Streak]

Re: School me on bumping shoulders + trimming question

I agree,Graham. The proper measurement tool is essential. I have been using the hornady head space guage and it seems to work well, but as you state, the mass produced dies, (such as my regular hornady FL die), will not do the bump job that I'm looking for. My head space actually shows that my brass grows instead of bumping back when I use the die. But, this seems to be a common problem with, as you state, mass produced dies not designed for this specific activity.

I've spent so much money on reloading tools, guages, dies, etc. that I probably did not need and, like I said, I've pretty much given up on bumping back the shoulder. Unless I read something that really changes my mind, I will just use my fired brass until they become difficult to "bolt" in my chamber and then I will simply FL size and trim as needed.

Reloading tools are like fishing tackle,..it seems like a lot of it is designed to catch reloaders and not fish.

 

[LoneWolfUSMC]

Re: School me on bumping shoulders + trimming question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fisky</div><div class="ubbcode-body">I FL size all the time.....But loading the same loads for 2 different guns may have more to do with that than anything. That, and I like to keep it simple.
</div></div>

Then bump for the tighter chamber.

Many dies are setup to size too much. I compared my sized brass to a loaded round of FGMM and found that my brass has had the shoulder pushed back more than new ammo. That is WAY too much. Since I load for a variety of rifles, most of the time I size back to FGMM spec.

I check the cases in a RCBS precision Mic. It's about the easiest method I have found.

 

[Red Ryder]

Re: School me on bumping shoulders + trimming question

Graham,

You say there's nothing wrong with bumping the shoulder .003 - .005 except for altering case wall thickness and case life. I disagree with you because that alters the internal dimensions of the case. Do that and you alter pressure. Second, you say that Chad is correct and Chad says to bump .001 - .002. As I stated in my first post, all the research I've done says .001 - .002 max so I too agree with Chad. Given all of the facts stated above, how do you justify bumping so much?

 

[LoneWolfUSMC]

Re: School me on bumping shoulders + trimming question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedRyder</div><div class="ubbcode-body">You say there's nothing wrong with bumping the shoulder .003 - .005 except for altering case wall thickness and case life. I disagree with you because that alters the internal dimensions of the case. Do that and you alter pressure.</div></div>

If you workup the load with the cases sized that way, pressure is a non-issue. It would be unwise to take a load running on the ragged edge of pressure and change anything without working it back up. Conversely if you run a mild load, bumping it .005 instead of .001 will most likely be just fine.

 

[MitchAlsup]

Re: School me on bumping shoulders + trimming question

I should probably let this one go--but::

In my experience, you cannot size a piece of brass by 0.001". By the time you assert enough pressure on the sholder for the brass to flow, it will flow at least 0.0017". I have run this experiment several times, looking for those cases that were between 0.0007 and 0.0013 too long. I would measure the case, lube up the case, run it through the die, wipe it down and remeasure the case. In almost ever instance, the case would come out exactly the same length as it went in. I went so far as to leave it in the die for multiple seconds.

I came to the conclusion that the brass does not flow until significant pressure is in play, and that when that much pressure gets into play, the case sholder moves to relieve the pressure. When insufficient pressure is in play, the case does not flow, and springs back to where it was before entry into the press.

 

[Graham]

Re: School me on bumping shoulders + trimming question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedRyder</div><div class="ubbcode-body">Graham, You say there's nothing wrong with bumping the shoulder .003 - .005 except for altering case wall thickness and case life. I disagree with you because that alters the internal dimensions of the case. Do that and you alter pressure. Second, you say that Chad is correct and Chad says to bump .001 - .002. As I stated in my first post, all the research I've done says .001 - .002 max so I too agree with Chad. Given all of the facts stated above, how do you justify bumping so much? </div></div>Back up one step. Before you can tell someone how much case sizing he needs you need to first measure the fired case and see how much expansion he is getting in his chamber. But we are not benchresters. The worst thing that can happen from sizing a case too much is shortened case life. I said that Chad knows, but to bump .001 for a tactical rifle? OK, but how do you do that reliably in volume when it takes a sizing die dimension of .005 under your chamber to reliably give you .003.

 

[fairchase]

Re: School me on bumping shoulders + trimming question

Here is what has worked for me . I bought a set of die shims from sinclair. There is a .003,.004,.005,.006,.007,.008, and .010 shim in the kit. I set up mt forester FL sizer per instructions. Then I add the shims to aquire the desired shoulder bump.

 

[Red Ryder]

Re: School me on bumping shoulders + trimming question

Graham,

I must admit you pose an interesting question.

 

[Graham]

Re: School me on bumping shoulders + trimming question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RedRyder</div><div class="ubbcode-body">Graham, I must admit you pose an interesting question.

</div></div>I'm not bad looking either.

 

[bkster]

Re: School me on bumping shoulders + trimming question

i have both the fl and neck only type s bushing dies from redding
and agree with chad... fl size every time and bump the shoulder
its one less step and for this game of run and gun... i loose 10-15 cases every shoot anyway... alittle longer brass life versus
a tight chamber and dirt and grass blowing into the gun... i'll fl size the brass every time
brass is one of the cheapest parts also...even if you only get 5 reloads and you pay $1each ... still less than any bullet worth shooting
im getting close to 9 reloads on some of my rem 260 brass... and this stuff is shit...
yeah the pockets are kinda loose, i toss 3-4 every reloading time
anneal by hand every 5 reload and trim when long.. but jfc
i paid $58/100

 

[Ratbert]

Re: School me on bumping shoulders + trimming question

I figured I might as well copy in a previous response I made about how to use an RCBS precision mic to measure headspace. If you get a Redding instant indicator instead (I much prefer) then use the GO gauge to setup the indicator so that it reads 0.x30" (what order of magnitude on the 10th you're on doesn't really matter since we're checking differences of thousandths) and preceed as below.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ratbert</div><div class="ubbcode-body">

The way I would do it (if I hadn't tossed the things in the bin and gotten the hornady and redding instant indicator) would be:

Get a GO gauge for your chosen chamber. Make sure the bolt WILL close on it (otherwise you've got bigger problems.) Assuming yes, put it in the Mic and measure it. Right that number down (on a Redding indicator this should be 0.x30"). Then take a piece of scotch tape stick it on the bottom of the headspace gauge and use a razor blade to trim it so you have a nice little circle of tape on the bottom. Put this in your gun and try to close the bolt. If it closes easily, take it out and measure again with the headspace gauge. It should be 0.001 to 0.002" longer. Right that down and add a 2nd layer of tape to the gauge and repeat. If it just BARELY closes, but requires a fair bit of force then take it out and measure again, THIS is your new zero. You want to size your brass so that they're 0.002-0.004 under this number(depending on your preferences for reliability vs absolute accuracy and your equipment's tolerances when sizing). If it won't close at all (which may be the case if your tape is on the thicker side) then take that measurement and split the difference between it and the last measurement where the bolt closed easily to find your zero.
</div></div>

Note that I suggest 0.002-0.004 under, this is under the absolute limits of your chamber and not under the size of your fired brass. Typically your fired brass should spring back about 0.001" so this should work out to 0.001-0.003 actual change to your fired brass.