Best Way To Setup Die For .001 Shoulder Bump
- Thread starter waynewjw
- Start date
waynewjw
CGN Regular
I have heard about removing firing pin before but never took it seriously as having a great net result. But based on comments on this and the forums I've asked the same question I will definitely be doing that.
Or do you mean the ejector?
Like the photo shows. measure the fired case and then set the die up to the desired amount of shoulder bump to .001 to .003.
If you pause at the top of the sizing stroke for 3 to 5 seconds the shoulder location will be more uniform. Meaning more uniform brass springback when pausing at the top of the ram stroke.
I don't know where this comes from but I have no confidence that it will actually work.
Annealing the case works, but pausing at the top does nothing. The spring back does not take a set that quickly. It might work if you let it sit for a month, but that's obviously not practical.
Annealing the case reduces spring back and therefore produces a more consistent set.
Redding Competion shell-holders, and uze your chamber as the guage.
The trouble with the Hornady tool, and others of that ilk is they measure from arbitrary datum point on the shoulder which is unlikely to conform to where your case hits on your chamber. Accuracy of the measuring device doesn’t change that, you can’t know where you are if you don’t know where you started.
The changes of your gauge being the same as your chamber and die are more or less zero, so is like measuring with a micrometer to cut with a chainsaw.
The trouble with the Hornady tool, and others of that ilk is they measure from arbitrary datum point on the shoulder which is unlikely to conform to where your case hits on your chamber. Accuracy of the measuring device doesn’t change that, you can’t know where you are if you don’t know where you started.
The changes of your gauge being the same as your chamber and die are more or less zero, so is like measuring with a micrometer to cut with a chainsaw
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To be honest I think you are about to go down a rabbit hole. Given the difficulty in accurately measuring such a small amount of shoulder bump and the challenges of actually consistently achieving it without more specialized tools than you are currently using I would ask why?
1. What Discipline do you intend to use the ammunition for. A big difference between F Class for instance, PRS or other PR sports as shot in Canada. Do you really need under .5 MOA ...like horespower in boats after a point the overwhelming investment for very small returns may become prohibitive and is that return even useful.
2. How robust do you need the load to be. Will you shoot it in pristine conditions or dusty, grimy, wet, muddy etc conditions.
3. What will be your testing method to decide if .001/.002/.003 actually makes a difference and how many rounds for it to be statistically significant.
4. Do you shoot well enough for the task
5. If the entire exercise is simply to see how small your groups can be then have at her.
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Watch the video below, there are many videos showing the pausing method at the top of the ram stroke.
https://www.youtube.com/watch?v=EcOyhAdvluQ
Munkey1973
CGN frequent flyer
- Location
- Regina, SK
IMO, the easiest way to set a Full Length for bump setting is similar to what you said in your opening post.
Thread it down until until it touches.. but I then back it out about 1/3 of a turn....(I think a coin might be too much in the case of most dies ?)
Then I walk it back down using a indexed die ring.
Indexed ring prevents "over doing it on the way down"
Here is a link to my to what I am talking about.
I can make/sell you one for cheap.
https://www.canadiangunnutz.com/forum/showthread.php/2255685-Sometimes-you-need-to-perfect-your-tools
Unrelated to my shameless shilling of my rings....Jerry offered some excellent advice in post # 20
IMO... for precision reloading, the brass should be sized until the bolt (stripped down) should just barely close on its own weight.
Stripped down meaning the ejector and firing pin have been removed.
An indexed lock ring aids in slowly walking the brass down.
IMO...never use a cam-over press for precision rifle reloading... I want dead stop press (e.g. Forster Co-ax)
Thread it down until until it touches.. but I then back it out about 1/3 of a turn....(I think a coin might be too much in the case of most dies ?)
Then I walk it back down using a indexed die ring.
Indexed ring prevents "over doing it on the way down"
Here is a link to my to what I am talking about.
I can make/sell you one for cheap.
https://www.canadiangunnutz.com/forum/showthread.php/2255685-Sometimes-you-need-to-perfect-your-tools
Unrelated to my shameless shilling of my rings....Jerry offered some excellent advice in post # 20
IMO... for precision reloading, the brass should be sized until the bolt (stripped down) should just barely close on its own weight.
Stripped down meaning the ejector and firing pin have been removed.
An indexed lock ring aids in slowly walking the brass down.
IMO...never use a cam-over press for precision rifle reloading... I want dead stop press (e.g. Forster Co-ax)
Oh I'm sure you can find lots of videos and web articles that claim it works. After 40 something years of hand loading, I think it's meaningless. He is testing a small sample size that feeds to support the result he wants to see. Guys chase ghosts all the time, and get questionable results using questionable methods.
The worst of all is that so and so does it and he won ### doing that, so everyone else should do that. In reality, they often don't win because of what they did, but in spite of what they did.
A win at the race on sunday sells cars on monday, as the saying goes. - dan
If you bend something so far that it remains deformed, that is plastic deformation. If you bend something to the point it only springs back, that is elastic deformation. If you bend something within the range of elastic deformation and hold it that way for a long time, there is a possibility of plastic flow of the material. But that doesn't typically occur until very long periods of time, and the effect is slight, like a magazine spring remaining compressed for decades, copper wires stretching after decades of hanging unsupported or the leaf spring of a truck after decades. I'm skeptical that holding the brass for seconds will result in any difference. Sounds like voodoo to me.
- Location
- Western Manitoba
There is most definitely something about "springy" and I will add "memory" in cartridge brass. I started a thread on CGN in 2020 - I had re-sized a number of PPU 8x57 into 9.3x57 brass - opened the necks to 9.3 and then further opened to pretty well "straight wall" brass - then started again with 9.3x57 die and worked that shoulder back down, so that bolt body would close with just faintest touch of resistance as bolt handle hit it's stop. As per usual here, something else caught my eye and attention and those brass and that rifle ended up laying on bench since then - so the cases were never fire-formed - just resized in a FL die. A few months ago, I got down into that pile far enough to find all that - and not a one would chamber without noticeable resistance - as if those cases had "sprung back". Is possible that there is a different bolt in that receiver, but I don't think so. Is sort of PITA to discover that nice snug fit from two years ago, is no longer "nice snug fit" in that chamber.
It is now my intention to make up some more of those brass, and actually fire form them this time, then do the "salt bath" annealing - hopefully they will then "stay" as I had left them.
It is now my intention to make up some more of those brass, and actually fire form them this time, then do the "salt bath" annealing - hopefully they will then "stay" as I had left them.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Anneal the cases you did before... then resize... problem is likely taken care of.
PRVI is particularly tough brass and will be springy. However, annealing will temper this and the brass works well.
Good luck
Jerry
PRVI is particularly tough brass and will be springy. However, annealing will temper this and the brass works well.
Good luck
Jerry
And if you do not anneal your cases the spring back can vary. And if you pause at the top of the ram stroke it will make the shoulder location more uniform. Meaning less shoulder spring back after resizing, and if you tried it you would not make the comment above.
Hornady makes comparator gauges matched to the red comparator holder that mounts on your caliper. These Lock-N-Load Headspace Gauges are inexpensive. You can get a set of five gauges for $31.99. Hornady explains: “The Lock-N-Load® Headspace Comparator… gauge measures variations in brass before and after firing or re-sizing. It allows for headspace comparison between fire-formed brass and re-sized brass.” IMPORTANT: Hornady states: “To determine the proper bushing diameter for your cartridge, simply add the neck diameter and the shoulder diameter and divide that number by two. Use the bushing closest to that number.” Hornady offers five: .330″, .350″, .375″, .400″, and .420″.
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waynewjw
CGN Regular
I’ve been using the Hornady comparator bushings for 5+ years and I have found them to be accurate in assessing fire formed size to resize shoulder. But pretty much all of this has been hunting loads where 1/2” - 1” at 100 yds has been “good enough”.
The trouble with measuring cases as they come out of the rifle is that they often take several firings to reach their maximum length. In other words, they may or may not be a snug fit in the chamber.
To accurately assess what length gives you .002" clearance, you need a case that definitely won't fit and work from that measurement.
To accurately assess what length gives you .002" clearance, you need a case that definitely won't fit and work from that measurement.
Munkey1973
CGN frequent flyer
- Location
- Regina, SK
This statement is true.
I'd be a fool to argue with this fact.
I've done my time and performed the experiment first hand.
When I fire my 308 Lapua Palma brass from my F T/R gun, and sample, say, 15 from a batch of 300, the head space may range from 1.626 to 1.6285.... about 0.0025 extreme spread.
Now, if were to skip a few cycles of of bump sizing then eventually a vast majority of my brass will get stretched out at the shoulder to which most brass sampled will be at 1.6285.
By this time the brass will be very hard to close the bolt (hard to open as well after the shot).... why would I ever want this (be it at a match or in the field pushing bush) ?
Whereas, if I bump size my brass (everytime) I never have this problem.
Currently, I anneal and bump them all. If and sample 15 brass of the lot, then I will be looking at 1.625 to 1.6255 (maybe 1.626).
Each cartridge is virtually sitting in the exact same spot in the chamber... that is money... F T/R competitor or otherwise.
At the end of the day, as a reloader, regardless of brass manufacturer, for a new rifle and/or batch of brass I will:
1) take my very first fired brass, from the 5% sample find the pieces with the longest headspace and use those to set up my sizing die for the bump.
2) (slowly) setup the die until it just start make contact the brass... (bear in mind, at first contact, it may actually make the headspace measurement longer by a couple thousands)
3) continue step #2 until the bolt (with the fire pin and ejector removed) just starts to close on it own weight (or with very little downward pressure)......
4) stop when #3 feels good
I the case of my F T/R gun, the bolt ran its smoothest with a 0.0035 bump (from the max sample length of 1.6285).
My next 308 chamber might need 0.002 ... or it might need 0.005... who knows.
My point at the end of my verbal diarrhea ......in a large enough batch, some of your brass will probably hit an absolute maximum at a first firing ... use those pieces to set up your die for sizing for your application.
The others will follow.
Honestly, sheading 1/8 MOA off of your group size (due to the world's best reloading technique) doesn't mean anything if your wind calls are out (due to wrong judgement) by 1 or more MOA..... let alone your fumbling and beating to close your bolt in the process.
This is true for any shooting application.
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This is an interesting point that people often don't realize. But we could expand on the point.
In calm conditions I've seen newbs win the match with an accurate rifle when the flags rarely lifted off the pole all weekend, (the proverbial trigger pulling contest) but when the wind blows hard enough, a guy with a lowly one MOA gun can take it if he knows wind, mirage, cloud cover and refraction.
All the wind reading skills in the world are useless if the wind does not blow.
