You guys using arbor press with presser gauge, I Read some just look at pressure spikes and some just how much pressure It take and adjust neck tension according. Just wondering what minimum is before you add neck tension and max before you lighten. And before you say depends on caliber let’s just say 6 mm or even more detail say 6 Br.
Arbor press and pressure
- Thread starter Bottom Fodder
- Start date
Ajwilly96
Gold $$ Contributor
I don’t have a ton of experience with it, but I only look for consistency. I’ve had rounds that seat at 10 psi shoot as good as rounds that seat at 40 psi.
It’s kind of an annoying rabbit hole, I will expand with a mandrel .001 under bullet diameter get around 35psi, if I brush the necks with lube it goes down to about 10psi. In my eyes it’s all about consistency
It’s kind of an annoying rabbit hole, I will expand with a mandrel .001 under bullet diameter get around 35psi, if I brush the necks with lube it goes down to about 10psi. In my eyes it’s all about consistency
Alex Wheeler
Site $$ Sponsor
That tool will not tell you the answer. Only the target will. Seating force is not the same as neck tension.
JMayo
Silver $$ Contributor
It tells me what i need to when compared to the target.
At 10 the bullet starts to seat and at 30-40 it fully seats. Any less it's too loose and bto will most likely change.
50- 60 fully seating, my groups get bigger.
This seems to be the same 6bra,6ppc. The 30br will snap into full seat faster than i can tell start if it's more than 30-40.
I put my thumb on the bottom of the top of the seater and start applying pressure to get start and fully seated #s.... (Realizing that a quicker work of the lever will most likely result in a change of bto compared to slow motion)
At 10 the bullet starts to seat and at 30-40 it fully seats. Any less it's too loose and bto will most likely change.
50- 60 fully seating, my groups get bigger.
This seems to be the same 6bra,6ppc. The 30br will snap into full seat faster than i can tell start if it's more than 30-40.
I put my thumb on the bottom of the top of the seater and start applying pressure to get start and fully seated #s.... (Realizing that a quicker work of the lever will most likely result in a change of bto compared to slow motion)
One Eye Pete
Gold $$ Contributor
I have been using the K&M arbor press with the standard force pack for about 10 years. I shoot mostly 6 and 7 mm. What I have found is the following.
1. the force required to seat a bullet is mainly dependent on two things a) the condition of the inside of the neck b) the amount of interference fit of the bullet in the neck (neck tension)
Of the two it seems like the condition of the inside of the neck can have the greater effect. Freshly cleaned brass with all of the carbon removed from the inside of the neck will give significantly higher force readings due to friction.
2. It is difficult to precisely gauge seating force and takes a lot of practice. In my reloading process after annealing and sizing I swab the inside of the neck with an alcohol/moly mixture. Then I run a mandrel into the neck to set the neck tension. The residual moly left in the neck is just enough to give me smooth bullet seating with consistent friction. My bullets (boat tails) normally seat somewhere between 20 to 40 on the indicator depending on how much neck tension I’m using.
3. A consistent chamfer on the case mouth is also essential (especially with flat back bullets). A spike in seating force is usually due to a bad chamfer or some other defect in the case mouth. The main reason I even use the gauge on the arbor press is to be able to detect these problems and cull out those rounds. With careful case prep these defects should be rare.
4. You can’t positively tell neck tension or how well a bullet will shoot by using a seating force gauge. Only testing on the target will tell. What the seating force gauge will tell you is if one of your rounds has a defect. With some experience you can normally tell a problem round just by the feel without even looking at the gauge.
1. the force required to seat a bullet is mainly dependent on two things a) the condition of the inside of the neck b) the amount of interference fit of the bullet in the neck (neck tension)
Of the two it seems like the condition of the inside of the neck can have the greater effect. Freshly cleaned brass with all of the carbon removed from the inside of the neck will give significantly higher force readings due to friction.
2. It is difficult to precisely gauge seating force and takes a lot of practice. In my reloading process after annealing and sizing I swab the inside of the neck with an alcohol/moly mixture. Then I run a mandrel into the neck to set the neck tension. The residual moly left in the neck is just enough to give me smooth bullet seating with consistent friction. My bullets (boat tails) normally seat somewhere between 20 to 40 on the indicator depending on how much neck tension I’m using.
3. A consistent chamfer on the case mouth is also essential (especially with flat back bullets). A spike in seating force is usually due to a bad chamfer or some other defect in the case mouth. The main reason I even use the gauge on the arbor press is to be able to detect these problems and cull out those rounds. With careful case prep these defects should be rare.
4. You can’t positively tell neck tension or how well a bullet will shoot by using a seating force gauge. Only testing on the target will tell. What the seating force gauge will tell you is if one of your rounds has a defect. With some experience you can normally tell a problem round just by the feel without even looking at the gauge.
This is my thoughts, I use one, but I'm just looking for consistency, not a number. Then group rounds accordingly by consistency. Ive had guns shoot just as accurate with a RCBS rock chucker press where I don't know the pressure at all, which matches what Alex says.
Once you've formed brass to stable, and load developed with that, and figured out that you need to leave carbon residue in the necks(normalizing friction), then you can correlate tension departures in a batch.
That won't do you any good with bullets already seated to see it.
But you can set offenders aside, and eventually see when it's time to reset the whole batch with a process anneal.
I use a different system where I measure pre-seating forces with an instrumented mandrel, and then adjust tension through neck sizing length to match all in batch. This, before any bullet seating.
That won't do you any good with bullets already seated to see it.
But you can set offenders aside, and eventually see when it's time to reset the whole batch with a process anneal.
I use a different system where I measure pre-seating forces with an instrumented mandrel, and then adjust tension through neck sizing length to match all in batch. This, before any bullet seating.
Sandstorm
Gold $$ Contributor
This right here….consistency and the odd ones are sighters.
Precisionhunter417
Silver $$ Contributor
I find my seating pressure is much lower when i brush the case neck just before charging and seating. Any debris even small deviation in the case neck will cause a slight increase in pressure during seating.
I still go by “feel” as i didnt spring for the force pack on my 21st century. The consistency of neck pressure has a direct effect on MY groups. If i get a spike i will usually mark that case and shoot it as a fouler or cold bore shot.
Great questions.
I still go by “feel” as i didnt spring for the force pack on my 21st century. The consistency of neck pressure has a direct effect on MY groups. If i get a spike i will usually mark that case and shoot it as a fouler or cold bore shot.
Great questions.
k260
Silver $$ Contributor
Can you expand on this? I would think there'd be a direct correlation between the two as One Eye Pete mentioned in point #1. If the bullet fits tighter it has to require more force to push it.
here's an example of seating force vs neck tension
same size bushing used to FL size brass....0.005" of neck tension/interference fit
120 - 150 lb of seating force on IDOD neck turned NO lube brass vs 35 - 50 lb 6x fired neck preped brass......again same .261" bushing used to size BRA brass
.261" sized neck OD and .266" loaded round.
same size bushing used to FL size brass....0.005" of neck tension/interference fit
120 - 150 lb of seating force on IDOD neck turned NO lube brass vs 35 - 50 lb 6x fired neck preped brass......again same .261" bushing used to size BRA brass
.261" sized neck OD and .266" loaded round.
Alex Wheeler
Site $$ Sponsor
Yes, there is but there are other factors friction related that show up more. So a bushing change will show up, but its small compared to friction related changes. Just for an example you can change a bushing size and maybe you see seating change 10 pounds. But you can do something that effects friction like clean the neck to bare metal or lube it and see 50+ pounds. So seating force is "mostly" a measure of friction.
Question about this graph. Is the initial force climb the amount necessary to start the bullet moving, then the balance is the amount to finally seat the bullet? Just been curious about these graphs and I won’t be buying an amp press anytime soon. I use the 21st Century hydro press.
I think so, the flatline is the distance the ram travels before it hits the seating stem, the first "hump" is the initial contact with the neck, second hump is the pressure ring clearing the neck/shoulder junction and then the rest of seating process.....at least that's how I understand it.
EDIT:
the second hump is NOT the pressure ring clearing the neck/shoulder junction
I do not seat my bullets deep enough to even get close to nk/shldr junction
Let me clarify.....the first hump is the boat tail touching the neck the second hump is the pressure ring coming into contact with the neck, hope it makes sense now.
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Let me say this as an engineer!! These grafts are measuring the frictional forces (pressure is a force) and maybe deformation pressure if the bushing or mandrel is too small!!
Alex is right on the graft with two different curves!!! The difference is the coefficient of friction between the two sliding surfaces!!! The upper graft (high pressure curve) is glidden copper/bare cartridge brass!! The lower graft(lower pressure curve) is glidden copper/carbon film on cartridge brass)!! The coefficient of friction is higher for copper/brass and is lower for copper/carbon!!!
This statement is going to blow forum members minds!!! The top, higher pressure curves are more scattered (high spread) due to imperfection inside the neck which affect friction!!! I inside ream (cool cut with higher shear forces) to create a uniform neck that eliminates the imperfections!!! And, the 6 reamer flutes leave micro grooves that act like air bearings thus lowering the coefficient!! Just like carbon build-up smooth the imperfections inside the neck!! The scatter can be greatly reduced!! A few firings fill those grooves and help adhere the carbon!!! Footings for the carbon deposits!! And, another plus for reaming is minimal brass removal leaving a thicker neck which will increase consistency in tension and reduce work hardening!!! Killing two birds with one stone!!!
All the pressure measurements are Kinetic (sliding) frictional forces or pressure!!
Kinetic friction (pressure) = coefficient of friction x the tension (pressure or force)!!!!
Once that bullet stops moving in the neck during seating, there is a larger force holding it!!! Static Friction is greater than Kinetics Friction because there is slight adhesion!! Some of the hills and valleys interlock at the micro perspective!!!
If the neck bushing or mandrel is too small, deformation pressure will be additive to the kinetic friction (pressure)!!!!
Alex is right on the graft with two different curves!!! The difference is the coefficient of friction between the two sliding surfaces!!! The upper graft (high pressure curve) is glidden copper/bare cartridge brass!! The lower graft(lower pressure curve) is glidden copper/carbon film on cartridge brass)!! The coefficient of friction is higher for copper/brass and is lower for copper/carbon!!!
This statement is going to blow forum members minds!!! The top, higher pressure curves are more scattered (high spread) due to imperfection inside the neck which affect friction!!! I inside ream (cool cut with higher shear forces) to create a uniform neck that eliminates the imperfections!!! And, the 6 reamer flutes leave micro grooves that act like air bearings thus lowering the coefficient!! Just like carbon build-up smooth the imperfections inside the neck!! The scatter can be greatly reduced!! A few firings fill those grooves and help adhere the carbon!!! Footings for the carbon deposits!! And, another plus for reaming is minimal brass removal leaving a thicker neck which will increase consistency in tension and reduce work hardening!!! Killing two birds with one stone!!!
All the pressure measurements are Kinetic (sliding) frictional forces or pressure!!
Kinetic friction (pressure) = coefficient of friction x the tension (pressure or force)!!!!
Once that bullet stops moving in the neck during seating, there is a larger force holding it!!! Static Friction is greater than Kinetics Friction because there is slight adhesion!! Some of the hills and valleys interlock at the micro perspective!!!
If the neck bushing or mandrel is too small, deformation pressure will be additive to the kinetic friction (pressure)!!!!
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Mark (quest450):
Your interpretation of the graft is excellent!! Good job!!! I can see the mechanics with your analysis!!! But, what is happening after the pressure ring/shoulder contact where there is an inversion of the curve (a cup or concave shape) showing a pressure drop??? This occurs on the 0.125 to 0.100 values on the X-axis!!!
Your interpretation of the graft is excellent!! Good job!!! I can see the mechanics with your analysis!!! But, what is happening after the pressure ring/shoulder contact where there is an inversion of the curve (a cup or concave shape) showing a pressure drop??? This occurs on the 0.125 to 0.100 values on the X-axis!!!
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