I am reloading on a Hornady lock n load progressive press for 223 to be fired in a bolt gun.I started getting case where the shoulder is bumped back too much. I loaded 20 rounds and 16 come out perffect and 4 rounds the shoulder is bumped back 4 thousands too much causing mis fires. Does anyone have an idea what could be going wrong?
problem with bumping the shoulder
- Thread starter rebs
- Start date
my cases have been fired three time or more
A little more information would be helpful, i.e. are the cases all the same lot, and what case lube do you use? How do you measure the amount of bump? What is your process? Is it possible that the short cases are the result of the shell plate not being fully populated?
cases are all the same lot. I measure the bump with a Hornady comparator on my caliper. I use my own spray lube that I mix alcohol and lanolin. I will have to check about the shell plate not being fully populated, I never thought about that. I am going to pull the shell plate today and completely clean it and put a drop of oil on the two ball bearings
that is the problem I am setup to set bump back .002 but a few cases turn out at .004 and they are the ones that won't fire
jsn
Gold $$ Contributor
Is the shell plate stamped or machined?
How long have you been using this press?
The photos of this press I can find online show it holds five pieces of brass, and you have 20% of your 20 that are out of spec.
Try loading another 20, keep track of which position on the shell plate each piece of brass was processed in, and see if you can isolate it to one position.
How long have you been using this press?
The photos of this press I can find online show it holds five pieces of brass, and you have 20% of your 20 that are out of spec.
Try loading another 20, keep track of which position on the shell plate each piece of brass was processed in, and see if you can isolate it to one position.
joshb
Gold $$ Contributor
WAG would be “play” in the press but I’m not familiar with the one you’re using. I have a couple RCBS progressives. When I figured out how to measure and produce “accurately “ sized brass, I found the progressives had too much play to do it. They are now used for pistol only.
Do you need to bump the shoulder back?
Try this:
1. Measure the unsized fired case (primer removed) head space and record it.
2. Set the die up so the die touches the shoulder but does not bump the shoulder back. Measure the sized case head space to verify that you are not bumping the shoulder or extruding the case (i.e., lengthening it). The measurement should be the same as the fire case head space or very close to it, i.e., preferably no more than - .001, +0.
3. Check the case in the rifle chamber preferably with the firing pin assembly removed. If the case chambers without resistance or only very slight resistance that's enough sizing for now. Record the size case head space. This becomes your sizing case head space base line for now.
4. Size and check 5 to 10 more cases using this procedure.
5. Reload and fire them checking for misfires. If misfires occur, it is not a sizing issue but probably something else.
The only reason to bump the shoulder is when the cases lengthen to the point where they will not chamber. When you full size, you are also sizing the radial dimension of the case which often is enough to allow proper chambering. Eventually with repeated firings and sizing some shoulder bumping becomes necessary. You only want to do the minimum amount necessary to ensure chambering.
While the .001 to .002" bumping is of good rule of thumb, it is not absolute since every rifle / lot of cases can be different. One of the advantages of measuring fired case head space is so you can custom adjust your sizing die for your rifle and lot of cases.
In my experience, with standard cases such as Rem, Win, Federal and Hornady, some variation is the metallurgy of the case exists from lot to lot and obtaining variation in sizing measurements is common. The goal is to keep the variation to a minimum and sizing only enough to allow proper chambering. One way to minimize variation is to use virgin brass from the same lot and dedicate a group of cases to a specific rifle and rotate the firing / sizing so all cases receive the same amount of wear.
As other have said, new cases need to fire form to the chamber of the rifle before bumping the shoulder. It may take several firings to accomplish this. By monitoring the fired and size case head space you can manage this process and avoid over sizing the cases.
Try this:
1. Measure the unsized fired case (primer removed) head space and record it.
2. Set the die up so the die touches the shoulder but does not bump the shoulder back. Measure the sized case head space to verify that you are not bumping the shoulder or extruding the case (i.e., lengthening it). The measurement should be the same as the fire case head space or very close to it, i.e., preferably no more than - .001, +0.
3. Check the case in the rifle chamber preferably with the firing pin assembly removed. If the case chambers without resistance or only very slight resistance that's enough sizing for now. Record the size case head space. This becomes your sizing case head space base line for now.
4. Size and check 5 to 10 more cases using this procedure.
5. Reload and fire them checking for misfires. If misfires occur, it is not a sizing issue but probably something else.
The only reason to bump the shoulder is when the cases lengthen to the point where they will not chamber. When you full size, you are also sizing the radial dimension of the case which often is enough to allow proper chambering. Eventually with repeated firings and sizing some shoulder bumping becomes necessary. You only want to do the minimum amount necessary to ensure chambering.
While the .001 to .002" bumping is of good rule of thumb, it is not absolute since every rifle / lot of cases can be different. One of the advantages of measuring fired case head space is so you can custom adjust your sizing die for your rifle and lot of cases.
In my experience, with standard cases such as Rem, Win, Federal and Hornady, some variation is the metallurgy of the case exists from lot to lot and obtaining variation in sizing measurements is common. The goal is to keep the variation to a minimum and sizing only enough to allow proper chambering. One way to minimize variation is to use virgin brass from the same lot and dedicate a group of cases to a specific rifle and rotate the firing / sizing so all cases receive the same amount of wear.
As other have said, new cases need to fire form to the chamber of the rifle before bumping the shoulder. It may take several firings to accomplish this. By monitoring the fired and size case head space you can manage this process and avoid over sizing the cases.
rwj
Gold $$ Contributor
If the Hornady progressive is the only press you have, configure it to not index the shell plate when sizing. Mark the shell plate station and always use the same one to bump shoulders. As others have stated, excessive movement of the shell plate and/or variation in elevation between each station will directly contribute to case dimensional variation.
I have - I had some lots of virgin brass, same lot, that was all over the place relative to chamber fit. It took several firings to establish a somewhat uniform case head space. In the interim, I used zero bump.
Is all of the brass from the same manufacturer? Lot?
Gargoyle
Finder Outer
The "missfires" is a weird one considering factory ammo has shoulders nowhere near fitting close to the shoulder of most chambers and they fire fine. I had misfires once when I had oil on my firing pin.
Your goal is to setback .002" I saw. You get some that set back .002" more than that. I have a bolt gun that fires Lapua brass to 3.617" as measured by my Hornady comparator. I check every piece of sized brass and accept 3.613-3.615". 3.616" is a tight bolt closure. I get some cases that need a couple passes through the die to get down to my acceptable length. Then I get some (2 in 50) that go 3.611"! I trash those cases.
I use a Lee turret press without index. I have tried different lube techniques. Seems Hornady One Shot gave me the most inconsistent seating. I finger the cases with Hornady imperial sizing lube now and have less problems. An RCBS shell holder helped out a bit too.
Your goal is to setback .002" I saw. You get some that set back .002" more than that. I have a bolt gun that fires Lapua brass to 3.617" as measured by my Hornady comparator. I check every piece of sized brass and accept 3.613-3.615". 3.616" is a tight bolt closure. I get some cases that need a couple passes through the die to get down to my acceptable length. Then I get some (2 in 50) that go 3.611"! I trash those cases.
I use a Lee turret press without index. I have tried different lube techniques. Seems Hornady One Shot gave me the most inconsistent seating. I finger the cases with Hornady imperial sizing lube now and have less problems. An RCBS shell holder helped out a bit too.
I had (have) the LNL press. I decided to move toward a single stage press as I felt the die bushings and the shell plate introduced too much movement / variation.
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