I just got my new set of dillon dies (they work NICELY) but they have a sticker advising me to "check the headspace" of my weapon--I'm reloading for about 4 different .223's (couple of sabre AR's, Remington XCR, etc)...is this completely necessary? I've never done it reloading for my other rounds, just want to be sure...Never had a problem before...
headspace question
- Thread starter mhptrooper
- Start date
Re: headspace question
Mmmmmm.
Have you got fireformed brass from each of your 4 rifles that you can identify as having been fired in each particular rifle?
If so, do the following...
Get some headspace guage tools... Hornady make a great little set, as do sinclair and a few others.
Check the "headspace" by measure from the base of the DEPRIMED case to the shoulder datum line (mid-point of the case shoulder).
Make note of which rifle has the longest fireformed cases in this instance and which has the shortest. If your lucky they would all be in a close proximity.
If not, you need to set your die to bump back the shoulder 0.002 (boltgun) to 0.003 (autoloader) on your SHORTEST case. If you do not do this, the rifles that have more headspace and hence longer cases, will not chamber properly and have a high likelyhood of a jam.
My advice is that if you have a big difference between the longest and shortest headspaces, either you want to devise a system that allows you to easily reconfigure your die OR get a second die. My suggestion is to look at the Redding comp shell holder set. Perhaps the one die setting, with a combination of different heights of shellholders will allow you to use the one one die on multiple rifles and still be able to achieve minimal sizing with each.
Mmmmmm.
Have you got fireformed brass from each of your 4 rifles that you can identify as having been fired in each particular rifle?
If so, do the following...
Get some headspace guage tools... Hornady make a great little set, as do sinclair and a few others.
Check the "headspace" by measure from the base of the DEPRIMED case to the shoulder datum line (mid-point of the case shoulder).
Make note of which rifle has the longest fireformed cases in this instance and which has the shortest. If your lucky they would all be in a close proximity.
If not, you need to set your die to bump back the shoulder 0.002 (boltgun) to 0.003 (autoloader) on your SHORTEST case. If you do not do this, the rifles that have more headspace and hence longer cases, will not chamber properly and have a high likelyhood of a jam.
My advice is that if you have a big difference between the longest and shortest headspaces, either you want to devise a system that allows you to easily reconfigure your die OR get a second die. My suggestion is to look at the Redding comp shell holder set. Perhaps the one die setting, with a combination of different heights of shellholders will allow you to use the one one die on multiple rifles and still be able to achieve minimal sizing with each.
Re: headspace question
Well your obviously doing ok, but from a safety aspect alone, your better off knowing how much headspace you have!
You can set your dies up to give minimal sizing (shoulder bump) without the headspace tools, but it's easier to use them IMO and you have a an actual measurement to go by.
All you need is a (hornady/Sinclair) comparator body, to fit on your calipres, with the correct bushing insert to fit your calibre.
Job done!
Probably under $30 too I guess.. Seeing as EVERYTHING seems to be cheaper over there..
Well your obviously doing ok, but from a safety aspect alone, your better off knowing how much headspace you have!
You can set your dies up to give minimal sizing (shoulder bump) without the headspace tools, but it's easier to use them IMO and you have a an actual measurement to go by.
All you need is a (hornady/Sinclair) comparator body, to fit on your calipres, with the correct bushing insert to fit your calibre.
Job done!
Probably under $30 too I guess.. Seeing as EVERYTHING seems to be cheaper over there..
Re: headspace question
VMAN: Wow-that sounds like alot of intense stuff...but I want this to work-How do these headspace guages work, and when do I use them in the whole process?
VMAN: Wow-that sounds like alot of intense stuff...but I want this to work-How do these headspace guages work, and when do I use them in the whole process?
Re: headspace question
It's just a tool that fixes on your caliper blade, with an insert the correct size
For your calibre.
You measure your case in you caliper as normal, but the tool sits against the case shoulder (datum line) so the measurement you get is base-shoulder.
All you do is compare fired brass, to sized brass, and whatever the difference is, that's how much you have/havnt bumped the shoulder back!
Simple.
Make sure you take your primers out of the fired brass first..
They can stick out a bit and give you a false reading.
Note- New brass can take a couple of firings before it's fully expanded to your chamber length.
It's just a tool that fixes on your caliper blade, with an insert the correct size
For your calibre.
You measure your case in you caliper as normal, but the tool sits against the case shoulder (datum line) so the measurement you get is base-shoulder.
All you do is compare fired brass, to sized brass, and whatever the difference is, that's how much you have/havnt bumped the shoulder back!
Simple.
Make sure you take your primers out of the fired brass first..
They can stick out a bit and give you a false reading.
Note- New brass can take a couple of firings before it's fully expanded to your chamber length.
Re: headspace question
I think the "real world" answer to this depends on what it is that you're trying to do.
Is it possible that none of this matters to you? Well, maybe... but, if you're looking for top performance out of your ammo then, vman has given you a good answer.
You do not want more shoulder bump than you have to have for both accuracy and brass life.
If you bump more than that, you can live without some of the other tools but, you will be loading ammo that won't shoot as well and, you will overwork your brass.
I think the "real world" answer to this depends on what it is that you're trying to do.
Is it possible that none of this matters to you? Well, maybe... but, if you're looking for top performance out of your ammo then, vman has given you a good answer.
You do not want more shoulder bump than you have to have for both accuracy and brass life.
If you bump more than that, you can live without some of the other tools but, you will be loading ammo that won't shoot as well and, you will overwork your brass.
Re: headspace question
mphtrooper, hope i didnt confuse you.
Sounds intense but once you wrap your head around it, its actually rather simple.
The guage set attaches to a digital caliper. You then zero the instrument. Get a deprimed, fired case. Put it in the guage and measure.
Now imagine this. A fully fireformed case is only marginally smaller than your rifles chamber due the natural spring back of brass. But at this point its about as close fitting as it will ever get.
So measuring a fireformed case will give you in theory the LONGEST reading from the base to the shoulder datum line (midpoint in the shoulder).
All the guage does is measure that. Once you have that measurement, you can adjust your die with confidence. If you have it set so that your bumping back fired cases about 0.001 to 0.002, then you know your getting minimal sizing.
This offers greater brass life, and more importantly in my opinion, greater safety as minimal sized brass isn't likely to seperate as rapidly as oversized brass.
mphtrooper, hope i didnt confuse you.
Sounds intense but once you wrap your head around it, its actually rather simple.
The guage set attaches to a digital caliper. You then zero the instrument. Get a deprimed, fired case. Put it in the guage and measure.
Now imagine this. A fully fireformed case is only marginally smaller than your rifles chamber due the natural spring back of brass. But at this point its about as close fitting as it will ever get.
So measuring a fireformed case will give you in theory the LONGEST reading from the base to the shoulder datum line (midpoint in the shoulder).
All the guage does is measure that. Once you have that measurement, you can adjust your die with confidence. If you have it set so that your bumping back fired cases about 0.001 to 0.002, then you know your getting minimal sizing.
This offers greater brass life, and more importantly in my opinion, greater safety as minimal sized brass isn't likely to seperate as rapidly as oversized brass.
Re: headspace question
The picture really did help, Thanks man! I'm gonna give this a try-I want this brass to last, and I want to get the best performance I can out of these rounds...
The picture really did help, Thanks man! I'm gonna give this a try-I want this brass to last, and I want to get the best performance I can out of these rounds...
Re: headspace question
The following is my stock description of how to setup and use a RCBS Precision Mic to measure headspace. If you get a Redding instant indicator instead (I much prefer) then use the GO gauge to setup the indicator so that it reads 0.x30" (what revolution of 10ths you're on doesn't really matter since we're checking differences of thousandths) and proceed as below.
Get a GO gauge for your chosen chamber. Make sure the bolt WILL close on it (otherwise you've got bigger problems.) Assuming yes, put it in the Mic and measure it. Right that number down (on a Redding indicator this should be 0.x30").
Then take a piece of scotch tape stick it on the bottom of the headspace gauge and use a razor blade to trim it so you have a nice little circle of tape on the bottom. Put this in your gun and try to close the bolt. If it closes easily, take it out and measure again with the headspace gauge. It should be 0.001 to 0.002" longer. Add a 2nd layer of tape to the gauge and repeat.
If (or when) it just BARELY closes take it out and measure again, THIS is your new zero. You want to size your brass so that they're 0.002-0.004 under this number(depending on your preferences for reliability vs absolute accuracy and your equipment's tolerances when sizing).
Note that I suggest 0.002-0.004 under, this is under the absolute limits of your chamber and not under the size of your fired brass. Typically your fired brass should spring back about 0.001" so this should work out to 0.001-0.003 actual change to your fired brass. Also if you poorly lubricate your brass (I personally have had bad luck getting reliable results with Hornady One-Shot) the shoulder or FL sizer can actually end up making the brass longer for some reason, or at the very least impossible to get repeatable sizing. Properly lubricated brass (Imperial sizing wax or RCBS liquid on a pad is very repeatable for me) should provide a nice smooth stroke and repeatable results +/- 0.001" . If the press stutters or sticks then you weren't lubed properly and actual results will vary +/- several thousandths.
Make sure you check overall case length and trim as needed after sizing. I personally trim every time, even if it's not strictly needed, so that I know I have a consistent bearing surface with the bullet.
Also note that I've measured new brass and factory loaded rounds and found them frequently to be 0.009" or more undersized from a GO Gauge.
The following is my stock description of how to setup and use a RCBS Precision Mic to measure headspace. If you get a Redding instant indicator instead (I much prefer) then use the GO gauge to setup the indicator so that it reads 0.x30" (what revolution of 10ths you're on doesn't really matter since we're checking differences of thousandths) and proceed as below.
Get a GO gauge for your chosen chamber. Make sure the bolt WILL close on it (otherwise you've got bigger problems.) Assuming yes, put it in the Mic and measure it. Right that number down (on a Redding indicator this should be 0.x30").
Then take a piece of scotch tape stick it on the bottom of the headspace gauge and use a razor blade to trim it so you have a nice little circle of tape on the bottom. Put this in your gun and try to close the bolt. If it closes easily, take it out and measure again with the headspace gauge. It should be 0.001 to 0.002" longer. Add a 2nd layer of tape to the gauge and repeat.
If (or when) it just BARELY closes take it out and measure again, THIS is your new zero. You want to size your brass so that they're 0.002-0.004 under this number(depending on your preferences for reliability vs absolute accuracy and your equipment's tolerances when sizing).
Note that I suggest 0.002-0.004 under, this is under the absolute limits of your chamber and not under the size of your fired brass. Typically your fired brass should spring back about 0.001" so this should work out to 0.001-0.003 actual change to your fired brass. Also if you poorly lubricate your brass (I personally have had bad luck getting reliable results with Hornady One-Shot) the shoulder or FL sizer can actually end up making the brass longer for some reason, or at the very least impossible to get repeatable sizing. Properly lubricated brass (Imperial sizing wax or RCBS liquid on a pad is very repeatable for me) should provide a nice smooth stroke and repeatable results +/- 0.001" . If the press stutters or sticks then you weren't lubed properly and actual results will vary +/- several thousandths.
Make sure you check overall case length and trim as needed after sizing. I personally trim every time, even if it's not strictly needed, so that I know I have a consistent bearing surface with the bullet.
Also note that I've measured new brass and factory loaded rounds and found them frequently to be 0.009" or more undersized from a GO Gauge.
