So wrong.
Why can't I measure shoulder bump?
- Thread starter 257Roberts
- Start date
BoydAllen
Gold $$ Contributor
We arrived at the amount of time in the flames of the annealer that gave that result, while preserving enough hardness in the neck so that heavy bullets loaded in magnums, fed from magazines did not move. The press was a Forster B2, Later we found that the problem returned after a couple of firings, which indicated that, going forward, we would have to anneal every other firing to keep the bump uniform. The first time we tried cases, the anneal was not enough. We added a second to the dwell time in the flames and got what we were looking for.
BoydAllen.
That doesn’t explain diddly squat as to how you sized the brass.
Anyway, never mind, I have no interest in what you to have to say.
Ever heard of a short chamber and a long die?
Doesn’t matter, ignore list you go.
That doesn’t explain diddly squat as to how you sized the brass.
Anyway, never mind, I have no interest in what you to have to say.
Ever heard of a short chamber and a long die?
Doesn’t matter, ignore list you go.
Most reloading presses do seem to have some deflection and inconsistency in them. I measure after sizing each case for my LR BR rifles. That said, I know of two presses that have virtually no deflection. That is the Prazipress and the Zeropress.
I still get a little variation in shoulder set back with my Prazipress, but it is much less than with the Co-Ax and RCBS presses I have, and most likely caused by inconsistency in lubing the cases.
Last edited:
No interest in what Boyd Allen says? You might want to rethink that. I have seen Boyd post for many years on various forums and he always seems factual, respectful, and helpful.
BoydAllen
Gold $$ Contributor
This is a case of speculation vs. experience. Toggling produces more consistent bump, but in some cases it is not an absolute requirement. I have done a lot of testing. If the brass is not to thick and/or springy and was uniformly annealed during manufacturing you can have consistent bump without it. For most brass that I have tried it does. That is the reason for the Redding competition shell holder sets. They allow the user to get toggle with a range of die settings, as long as you do not need a shorter than standard holder. Another thing that complicates die setting is that as brass is fired and FL sized more and more, it becomes more work hardened, so that the same setting will not give the same result.
Last edited:
Rook 6
Silver $$ Contributor
I know OP is dealing with once fired brass. Annealing has already been mentioned but I'll say again to OP you might try annealing the brass as an initial point of reference if you haven't done that already and go through the bumping process again. Might improve things? Hopefully you will find you don't have to grind anything.
Dusty Stevens
Shiner
Just put him on the ignore list. Sometimes you have to know your audience and i dont think hes done his research.
I fought this battle for years, seeing cases 1-2 thou off +/-. Then using a gas annealer every 2 to 3 firings, I saw a slight improvement. Annealing every firing, I began getting only .001 +/- difference.
When I went to a AMP Aztec, annealing each firing, and using the PMA die adjuster, I am where I wanted to be.
That said, the cases have to be fully formed prior to setting up my die for a given chamber.
The only con I can see is the price of a PMA for every rifle's sizing die.
When I went to a AMP Aztec, annealing each firing, and using the PMA die adjuster, I am where I wanted to be.
That said, the cases have to be fully formed prior to setting up my die for a given chamber.
The only con I can see is the price of a PMA for every rifle's sizing die.
BoydAllen
Gold $$ Contributor
On the subject of die adjustment to try to have one or two thousandths of bump, it seems to me that anyone who suggests adjusting by something as large as an eighth of a turn of the die may have failed to do a little basic math. Dies have 14 threads to an inch, which means that it takes 14 turns to move a die up or down an inch. If you divide 1" by 14 you will find that one turn gives about .071 of vertical change in die position in the press. Divide .071 by 8 and you get .0089 or about .009.
Lone Hunter
Silver $$ Contributor
NO... I like him where he is. LOL
BoydAllen
Gold $$ Contributor
Those instructions have always been wrong, assuming you want to get any sort of decent brass life, and that your rifle does not have absolutely minimum headspace. One of the problems that I can run into when trying to help someone upgrade his die setting skills it that he may think that factory instructions came down from Mt. Sinai on stone tablets.
Apparently I have no social life, or meaningful things to do. Most folks spend their weekends at BBQs or home maintenance or ball games, I spend my day pondering brass and taking measurements and trying to figure out what it all means. Fascinates the hell out of me. Anyways, I took 30 pieces of 3X fired Lapua 308 brass and did a little data collection. I spent some serious time with my Hornady bump gauge tool and figuring out how to use it consistently and then playing with my Redding FL bushing die to size in various increments.
Of the 30 pics, fired late last fall in my Palma gun, all of which gave .30-.40" groups off the bench, the fired length from head to shoulder datum ranged from 1.625-1.628", with the mean value being 1.626". The listed SAAMI chamber spec is 1.630-1.640", my 3X fired brass is still shorter than SAAMI.
I then used 2 different presses, a basic Lee challenger single stage and Redding T-7 turret, using the same Lee universal shell holder [mine measured .124] and screwed the Redding FL bushing die until it firmly contacted a raised ram. Both presses gave the exact same result. All 30 sized pieces of brass GREW in shoulder length by exactly .002".
Using the same two presses and shell holder, it took an additional "1/16th to 1/8th" [very very slight] die turn [past initial contact] to bump the shoulders back down the .002", to the original fired shoulder lengths. [Just as a side note, in all cases, the OAL length of the brass grew by .004-.005"].
Another interesting point, annealing made no difference in the numbers. I annealed half the batch just to compare, and the exact same .002" growth, and then .002" set back were observed. The OAL growth was also the same at .004".
I then realized thru numbers, at least for this batch, that I didn't need to be bumping shoulders at all, because even when the shoulders grew by .002", the worst case was 1.630" and that brass still easily chambered in my gun. So then I wanted to know what the chamber of my gun actually was, so I went on the hunt in my stash of brass for something long and obnoxious, and found some old once fired LC72 match in the 1.645" range. Backing the die out and running down in micro increments, I found that a 1.631" shoulder will not chamber in my gun, no way no how, but a 1.630" will chamber just fine.
What's interesting to note, the die position for achieving 1.630" with the LC72 Match was past initial shell holder contact, or slightly more "cam over" than with my Lapua brass. This makes sense to me as the brass was bigger to start with and likely took more camming force to cause the same amount of brass engagement into the die body.
All this raises more questions though, and I am anxious to discover more details.
My initial conclusion is this, the overall process is extremely repeatable, and even my cheap tools can give very consistent results. I made some very poor "universal" numerical assumptions that I proved wrong thru a little data collection. [Just because brass is fired in your gun, don't assume that's your chamber dimension]. I think the takeaway here is that obviously every gun, brass, press, die, shell holder is NOT the same, and everybody's process by default must be a little different to achieve the same [or proper] result. Each individuals process is likely different for each cartridge they load for as well. If a person takes the time to do some measuring of what is actually happening with their tools and what works in the specific firearm, I think the whole process can be very precise and repeatable. I demounted and remounted all my tools into multiple presses, even removed and remounted my Hornady bump gauge, and I was able to repeat every measurement I took. This activity sure helped ease some of my questions & concerns, but also taught me that I need to pay a little closer attention to initial measurements, die setting and record keeping.
I hope this post was helpful. Not meant to stir the pot, just sharing my findings.
Of the 30 pics, fired late last fall in my Palma gun, all of which gave .30-.40" groups off the bench, the fired length from head to shoulder datum ranged from 1.625-1.628", with the mean value being 1.626". The listed SAAMI chamber spec is 1.630-1.640", my 3X fired brass is still shorter than SAAMI.
I then used 2 different presses, a basic Lee challenger single stage and Redding T-7 turret, using the same Lee universal shell holder [mine measured .124] and screwed the Redding FL bushing die until it firmly contacted a raised ram. Both presses gave the exact same result. All 30 sized pieces of brass GREW in shoulder length by exactly .002".
Using the same two presses and shell holder, it took an additional "1/16th to 1/8th" [very very slight] die turn [past initial contact] to bump the shoulders back down the .002", to the original fired shoulder lengths. [Just as a side note, in all cases, the OAL length of the brass grew by .004-.005"].
Another interesting point, annealing made no difference in the numbers. I annealed half the batch just to compare, and the exact same .002" growth, and then .002" set back were observed. The OAL growth was also the same at .004".
I then realized thru numbers, at least for this batch, that I didn't need to be bumping shoulders at all, because even when the shoulders grew by .002", the worst case was 1.630" and that brass still easily chambered in my gun. So then I wanted to know what the chamber of my gun actually was, so I went on the hunt in my stash of brass for something long and obnoxious, and found some old once fired LC72 match in the 1.645" range. Backing the die out and running down in micro increments, I found that a 1.631" shoulder will not chamber in my gun, no way no how, but a 1.630" will chamber just fine.
What's interesting to note, the die position for achieving 1.630" with the LC72 Match was past initial shell holder contact, or slightly more "cam over" than with my Lapua brass. This makes sense to me as the brass was bigger to start with and likely took more camming force to cause the same amount of brass engagement into the die body.
All this raises more questions though, and I am anxious to discover more details.
- Is all brass created shorter than SAAMI initially?
- Is there a better way to measure chamber dimensions outside of chamber casting or incremental sizing of brass?
- At what rate does brass spring back or shrink happen?
- There are many different reamers/brands for the same cartridges, how different are the dimensions?
My initial conclusion is this, the overall process is extremely repeatable, and even my cheap tools can give very consistent results. I made some very poor "universal" numerical assumptions that I proved wrong thru a little data collection. [Just because brass is fired in your gun, don't assume that's your chamber dimension]. I think the takeaway here is that obviously every gun, brass, press, die, shell holder is NOT the same, and everybody's process by default must be a little different to achieve the same [or proper] result. Each individuals process is likely different for each cartridge they load for as well. If a person takes the time to do some measuring of what is actually happening with their tools and what works in the specific firearm, I think the whole process can be very precise and repeatable. I demounted and remounted all my tools into multiple presses, even removed and remounted my Hornady bump gauge, and I was able to repeat every measurement I took. This activity sure helped ease some of my questions & concerns, but also taught me that I need to pay a little closer attention to initial measurements, die setting and record keeping.
I hope this post was helpful. Not meant to stir the pot, just sharing my findings.
NorCalMikie
Gold $$ Contributor
If you can't get the brass sized to your liking, try a mod on the shell holder.
Chuck one upside down in a drill press and run it down on an "oiled sharpening stone". Comes out looking like it was factory made AND works like a champ!!
Measure first and when you've taken the right amount off, mark it so it doesn't get mixed up with a standard/non modified shell holder.
MUCH easier than trying to modify a die. And shell holders are ea$ier to replace than die$.
BoydAllen
Gold $$ Contributor
Oh well, I guess that I will just have to suffer through. You asked me a rather general question and I gave the information that I thought that you were looking for. If you wanted other details, you should have just asked and I would have told you.
Dusty Stevens
Shiner
Dont feed the troll boyd.
BoydAllen
Gold $$ Contributor
Excellent advice.If you can't get the brass sized to your liking, try a mod on the shell holder.
Chuck one upside down in a drill press and run it down on an "oiled sharpening stone". Comes out looking like it was factory made AND works like a champ!!
Measure first and when you've taken the right amount off, mark it so it doesn't get mixed up with a standard/non modified shell holder.
MUCH easier than trying to modify a die. And shell holders are ea$ier to replace than die$.
Calling me a troll hey?
Good for you.
Good for you.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.