This is my first time trying to setup and do a shoulder bump. Using a hornady headspace gage 375, measured once fired case, set to zero on caliper and checked several other cases, basically all zero. Set die in press and ran case through die several times turning die down until i had .002 shoulder bump. Ran about 30 cases through die and tested each one with a 002 to 003 result. Measured case length before running through die they were 1.915 to 1.917, after going through die 1.919 to 19.21. Trimmed case necks back to 1.916. I have a Wilson 6.5 Creedmoor case gage and decided to measure a couple cases. Heres my problem, Once fired cases were all at the top level on the gage. measured the cases that i shoulder bumped and they were about 001 to 002 below the lower level. basically a 006 to 007 setback. What did i do wrong, our are these tools not compatible.
6.5 creedmoor shoulder bump problem
- Thread starter RAM2940
- Start date
Are you measuring the fired cases without the primer? Sometimes the firing pin impact can have a ridge that is proud of the case head, messing up the measurements.
Also, when you're adjusting your die, I'd recommend using a different case for each adjustment. You may end up over adjusting the die if you try to bump back 1 piece of brass 5 or 6 times, it gets harder each time, making you over adjust - because it doesn't respond like a fired piece.
Also, when you're adjusting your die, I'd recommend using a different case for each adjustment. You may end up over adjusting the die if you try to bump back 1 piece of brass 5 or 6 times, it gets harder each time, making you over adjust - because it doesn't respond like a fired piece.
jepp2
Gold $$ Contributor
Suggestions. First use the 0.400 headspace comparator (Hornady has incorrectly identified which comparator to use).
Next, determine the case head to datum length in your rifle where you get bolt contact on a stripped bolt. Your cases may be well short of this on the first firing, but sizing them with the sizing die high will move the shoulder forward some. Once you find what length results in bolt contact on closing, size 0.002" shorter than THAT measurement.
Using different comparators can result in different readings since they are all relative. Only the Whidden case gauge is spot on.
Next, determine the case head to datum length in your rifle where you get bolt contact on a stripped bolt. Your cases may be well short of this on the first firing, but sizing them with the sizing die high will move the shoulder forward some. Once you find what length results in bolt contact on closing, size 0.002" shorter than THAT measurement.
Using different comparators can result in different readings since they are all relative. Only the Whidden case gauge is spot on.
Some variation in measured shoulder bump is normal in my experience. A variation of .001", is good in my experience.
The dimensions you should focus on is the case head space as fired with primer removed and the sized case head space. Measure at least three to five cases to obtain an idea of consistency in the brass /sizing / measuring consistency.
I don't like the Hornady bump gauges because it has component parts, and the interfaces can affect consistency. I like the Whidden bump gauge because it is single piece without component part interfaces. Place match marks on the Hornady holder and inserts so they align the same each time if you're changing out inserts to another caliber group.
Normally when a case length increases after sizing, it means that you're extruding the case, i.e., lengthening it because the die is not touching the shoulder. This not the situation in your case because you are clearly touching the case shoulder with the die because you have measured shoulder set back. The only thing I can think of is that the neck in being either stretched by the expander button or less likely being extruded because you have a very tight neck dimension in the die. How much resistance are you experiencing from the expander button?
The Wilson Case Gauges can be useful as a qualitative tool, less so as a quantitative tool unless you use it conjunction with a dial indicator to measure actual case head space. It's sounds like you used it properly for a qualitative check, checking the fired case then the sized case. I agree the results you reported reflects too much shoulder bump but that doesn't agree with your measured results with the Hornady tool. I'm wondering if something is amiss with the Hornaday tool / caliper / operator error.
As an ultimate check on your sizing, always check a few cases in the rifle chamber. Removing the fire pin assembly will help you access by feel the adequacy of your sizing. The bolt should offer very slight resistance to closing the bolt on a sized case. Always remember, there are only two reasons to size a case, 1. So it will chamber reliability with minimal sizing, 2. So it will hold the bullet.
There is nothing magically about a .002" shoulder bump. In many rifles, a zero to .001 bump will work very well. Why? Because the FL die is also sizing the radial dimension of the case which offers just a much if not more resistance to chambering.
I'm not a fan of neck sizing but many reloader can get away with neck sizing only (no bump) for several reloads before encountering any chambering difficulty. Many times, it's not the case head space causing the chambering difficulty, it's the radial expansion.
The dimensions you should focus on is the case head space as fired with primer removed and the sized case head space. Measure at least three to five cases to obtain an idea of consistency in the brass /sizing / measuring consistency.
I don't like the Hornady bump gauges because it has component parts, and the interfaces can affect consistency. I like the Whidden bump gauge because it is single piece without component part interfaces. Place match marks on the Hornady holder and inserts so they align the same each time if you're changing out inserts to another caliber group.
Normally when a case length increases after sizing, it means that you're extruding the case, i.e., lengthening it because the die is not touching the shoulder. This not the situation in your case because you are clearly touching the case shoulder with the die because you have measured shoulder set back. The only thing I can think of is that the neck in being either stretched by the expander button or less likely being extruded because you have a very tight neck dimension in the die. How much resistance are you experiencing from the expander button?
The Wilson Case Gauges can be useful as a qualitative tool, less so as a quantitative tool unless you use it conjunction with a dial indicator to measure actual case head space. It's sounds like you used it properly for a qualitative check, checking the fired case then the sized case. I agree the results you reported reflects too much shoulder bump but that doesn't agree with your measured results with the Hornady tool. I'm wondering if something is amiss with the Hornaday tool / caliper / operator error.
As an ultimate check on your sizing, always check a few cases in the rifle chamber. Removing the fire pin assembly will help you access by feel the adequacy of your sizing. The bolt should offer very slight resistance to closing the bolt on a sized case. Always remember, there are only two reasons to size a case, 1. So it will chamber reliability with minimal sizing, 2. So it will hold the bullet.
There is nothing magically about a .002" shoulder bump. In many rifles, a zero to .001 bump will work very well. Why? Because the FL die is also sizing the radial dimension of the case which offers just a much if not more resistance to chambering.
I'm not a fan of neck sizing but many reloader can get away with neck sizing only (no bump) for several reloads before encountering any chambering difficulty. Many times, it's not the case head space causing the chambering difficulty, it's the radial expansion.
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I wasn't clear - my bad. I meant to refer to the amount of variation, i.e., difference between .002 and .003, i.e., .001" variation in shoulder bump between sized cases. Not a variation .002 to .003 which I agree is excessive variation.
I will edit the post. Thanks.
.
Im thinking that using the 375 headspace gage might have given a bad reading for the case. As Jepp2 mentioned that Hornady made a mistake and should have used a 400 headspace gage. All once fired cases show a correct reading with the wilson case gage. before resizing. I did 30 cases and checked each one before and after as they were ran through the f l sizer.
Size with a .005" feeler gap between shell holder and fl die. Will empty brass chamber & let bolt close? Yes, load and fire.
Do same with same 2 times fired brass, same die setting, with bolt close? May not. Adjust die till empty brass chambers.
I like to feel a slight crush fit on sized brass, when closing the bolt. Take this as chamber maximum. Now bump back .002"
Do same with same 2 times fired brass, same die setting, with bolt close? May not. Adjust die till empty brass chambers.
A little more then needed. Safe to fire. Most standard dies & shell holders, when touching, will produce about .005" shoulder set back.
I like to feel a slight crush fit on sized brass, when closing the bolt. Take this as chamber maximum. Now bump back .002"
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That's my take as well. As long as it's somewhere between the neck and body junctions, it should be fine.
Coyotefurharvester
Silver $$ Contributor
What you did wrong was set die with comparator measurements, than "verify" with a different type of gage. When you have brass fully fire formed, set the die using the rifle chamber. Than take a measurement of the same case with both tools, keep those for a reference. If the ammo will be used in more than one rifle, the case gage or an ammo checker will be best. Set up your die gutted. Primer removed from case. The Wilson also is a length checker, if the case is long and setting on a surface the case will stop prematurely.
6BRA
Gold $$ Contributor
Anneal brass every time, springback will occur and it can be terrible at times. The finest tool I have seen for headspace fast repeatable results is the redding instant indicator. Dial indicator. Pull your press handle and boom..instant consistent results. Pricey...get rid of the calipers. Jmo
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