Bumping shoulders, how do you know?

[NoFail]

I use a "Dillon precision head space/case gauge" for .308.
I know where I end up after I run through a FL Forster sizer die and then check case in the Dillon gauge but I don't know how much I'm actually bumping shoulder. How do you guys know you're bumping back .001" or whatever? Is there a measurement tool I don't know about?
Thanks....

 

[MtnCreek]

Re: Bumping shoulders, how do you know?

Not the best way, but…

Put clean, fired brass in the case gauge. Measure with calipers.
After sizing, put it back in the gauge (After Cleaning Off Lube) and measure again.
The difference is the amount the shoulder was pushed back.

 

[knight_dive]

Re: Bumping shoulders, how do you know?

Hornady Headspace Gauge

Measure a fired cartridge and then adjust the sizing die until you get the desired amount of shoulder bump. The gauge is a comparator, the number won't be an exact measurement of anything, but it allows you to "compare" the difference between fired and sized cases.

 

[FLIGHT762]

Re: Bumping shoulders, how do you know?

Read this, from the top of this forum under brass prep:

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1696162#Post1696162

 

[YAOG]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NoFail</div><div class="ubbcode-body">I use a "Dillon precision head space/case gauge" for .308.
I know where I end up after I run through a FL Forster sizer die and then check case in the Dillon gauge but I don't know how much I'm actually bumping shoulder. How do you guys know you're bumping back .001" or whatever? Is there a measurement tool I don't know about?
Thanks.... </div></div>
You need one of these, a Redding Instant Comparator. Comes with a minimum SAAMI spec gauge and other bits and pieces to use for comparison with your fired brass and loaded rounds. Set it up and measure a SAAMI spec case then measure your fired brass to see what your headspace is. Measure your fired cases then size one and measure it to see where you are setting the shoulder back. You want you loaded rounds to have 0.001" to 0.002" of actual headspace in your chamber. This is one of the best tools for quickly and accurately measuring headspace in your weapons. I have the Hornady LnL headspace and bullet comparator tools and while they are better than nothing once I used the Redding Instant Comparator I coulld see no good reason to go backward though it is handy for quick measurements that I don't have the Redding Gauge setup for.

HTH!

 

[NoFail]

Re: Bumping shoulders, how do you know?

Thanks guys,, have somthin to go on now

 

[ChrisGarrett]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NoFail</div><div class="ubbcode-body">Thanks guys,, have somthin to go on now

</div></div>

I use the Horandy headspace gage set and that's the cheapest way to go at $33-$35.

The Redding is nice, but a single cartridge option, whereas the Horandy set will do most bottle neck carts.

Absent spending some money, you can take that fired case and chamber it, checking for resistance and then turn the die down an eigth of a turn and rechamber until you don't feel resistance, or you can close the bolt easily.

Honestly, with bolt guns, you don't have to 'always' bump the shoulders back and can get away with just neck sizing, but at some point, those cases are going to grow and a shoulder bump 'might' be necessary.

Chris

 

[NoFail]

Re: Bumping shoulders, how do you know?

^ mine is a AR I assembled, but all the guts are JP Enterprises, except for buffer. I've got 500 rounds or so through it. All except for 15 of them are my hand loads. I've been trying to make the best ammo I can using mostly Winchester brass and Amax. Maybe when I learn how to do a good OCW I'll settle on a load that makes the gun happy. But maybe I have shot though some already but I don't shoot good enough to know, idk... Got a new SS 12x42 to shoot for accuracy during OCW's and that helped a lot. But when I try and do 5 shot groups with a load that looks promising i get lots of fliers. I haven't figured it out yet, I just keep shooting since most of those fliers are probably me. I have some I just loaded to try another test with Varget & 168 Amax, plan on tomorrow with crono, but this is really hard to get tight groups.

 

[ChrisGarrett]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NoFail</div><div class="ubbcode-body">^ mine is a AR I assembled, but all the guts are JP Enterprises, except for buffer. I've got 500 rounds or so through it. All except for 15 of them are my hand loads. I've been trying to make the best ammo I can using mostly Winchester brass and Amax. Maybe when I learn how to do a good OCW I'll settle on a load that makes the gun happy. But maybe I have shot though some already but I don't shoot good enough to know, idk... Got a new SS 12x42 to shoot for accuracy during OCW's and that helped a lot. But when I try and do 5 shot groups with a load that looks promising i get lots of fliers. I haven't figured it out yet, I just keep shooting since most of those fliers are probably me. I have some I just loaded to try another test with Varget & 168 Amax, plan on tomorrow with crono, but this is really hard to get tight groups. </div></div>

My head hurts.

Paragraphs are your friend.

Start over.

Chris

 

[NoFail]

Re: Bumping shoulders, how do you know?

^ ok Chris


Originally Posted By: NoFail
^ mine is a AR I assembled, but all the guts are JP Enterprises, except for buffer. I've got 500 rounds or so through it. All except for 15 of them are my hand loads. I've been trying to make the best ammo I can using mostly Winchester brass and Amax.

Maybe when I learn how to do a good OCW I'll settle on a load that makes the gun happy. But maybe I have shot through some already but I don't shoot good enough to know, idk... Got a new SS 12x42 to shoot for accuracy during OCW's and that helped a lot. But when I try and do 5 shot groups with a load that looks promising i get lots of fliers.

I haven't figured it out yet, I just keep shooting since most of those fliers are probably me. I have some I just loaded to try another test with Varget & 168 Amax, plan on tomorrow with crono, but this is really hard to get tight groups.

I think the main improvement I can make with my ammo is making sure head space is good, which I think it is anyway, and consistent neck tension. Right now neck tension is the big one.

My Forster FL die leaves me with .002" neck tension with the Win brass. I hit the sizing ball with 600 then 1500 wet/dry paper to polish it. I still need to go some more with that. I think I should have .003" tension for the semi auto, maybe .004" idk.

 

[pmclaine]

Re: Bumping shoulders, how do you know?

I bought an RCBS precision case micrometer when I could combine money off and free shipping from Sinclair.

My Dillon gauge only tells me if the case will fit a chamber. The steps for case length are so small you dont get much information from them.

The RCBS gauge allows me to know what my cases are doing in relation to SAAMI spec. The zero setting on the case gauge is the SAAMI spec for an unfired cartridge. My rifles blow my cases out to +.003-+.004. I set my dies to bump back to +.001-+.002. My size die is not set tight to the shell plate as per Dillons spec. Per Dillons settings my cases are sized to -.004/-.005. I end up working the brass less based on info I got from the gauge.

I found it to be useful not a gimmick. The tool is cartridge specific and I dont know how many calibers they carry.

 

[milo 2.0]

Re: Bumping shoulders, how do you know?

Does it really matter how much you are bumping your cases?
The case needs to rechamber in your gun, set the die accordingly. If it is bumped "001" or ", 005" it still needed to be done.
Tools are neat, but not always needed. Does the guy bumping "0005" have more accurate ammo than you bumping "003"? I think not.. There is more to it.

My advice is to skip on the gadgets and buy bullets and brass, load them and shoot. Save the gadget buying until you are older, then it will be a neat conversation piece for happy hour with your buddies. No one, even your gun gives a flying fuck how much the shoulder was bumped.

I have two fully custom guns that need the shoulder bumped every firing, and they shoot, so don't complicate matters.

 

[pmclaine]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body">Does it really matter how much you are bumping your cases?
</div></div>

To a geek it does and I'd like to say "Hi my name is Phil, I am a geek, and I have a problem."

I load 30-06 and brass is expensive. If bumping my brass to a minimum required allows me to get two or more extra loadings before I have to scrap the brass my geekiness pays off. I'm finding for my guns I dont need to screw my size die down to the plate plus a 1/4 turn. Less sizing = less stretching/working the brass.

Now as long as I dont think about my primer pockets failing long before my cases would ever seperate I can justify my RCBS case gauge micrometer. Please dont pee in my Cheerios.

 

[milo 2.0]

Re: Bumping shoulders, how do you know?

PM,
I surely didn't mean to pee in your cheerios. Nor was my comment directed at you. I was just telling the guy to bump what is neccesary to refeed cases.
I find a caliper and comparator gauges do the same for less, if I really need to know.
We all have a small fortune in this shit, just trying to save a guy a buck.

All said, is a wake up pee more stout than a watered down afternoon one?????
Sorry,
Miles

 

[pmclaine]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body">

All said, is a wake up pee more stout than a watered down afternoon one?????
Sorry,
Miles </div></div>

I eat a bowl of asparagus every morning than make it a goal to stand next to someone at urinal row for fun.

 

[QuiggyB]

Re: Bumping shoulders, how do you know?

This one works for any cartridge you will load, with any shoulder angle.

http://www.larrywillis.com/

 

[avidflyer]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuiggyB</div><div class="ubbcode-body">This one works for any cartridge you will load, with any shoulder angle.

http://www.larrywillis.com/

</div></div>

I have one....its ok but not great ,you need to position it the same way all of time (of course as with any tool). point is it can be hard to use and the top adjustment is set with a set screw...going to mod mine to a shell holder for the bottom and a compairitor on top that I can switch out for cases, bullets etc...

 

[MitchAlsup]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body"> Does the guy bumping "0005" have more accurate ammo than you bumping "003"? </div></div>

In actuality, you cannot bump the shoulder less than a certain amount. Brass is springy, and when insufficient pressure is applied, it will simply spring back.

A few years ago I ran an experiment on this with some 308 cases (twice fired). In the experiment, I would measure the shoulder datum position, lube the case, run it through my body die, and then measure the shoulder datum position again. To my surprise, I could not push a shoulder back by less than 0.0015. If I tried, the case would not size at all--it came back out of the die with the shoulder at the same measurement as before. I tried multiple cases (dozens) with the same result. Either the shoulder went back 0.002 or it did not move.

After the experiment, I did some math on the pressure exerted on the lever and the case wall diameter and found that you are exerting pressures equal to the 48K PSI youngs modulous of the brass. That is, you exert enough force, and because the cae walls are thiin, there is enoughpressure for the brass to actually flow. If the brass does not flow, it will return to its original position.

 

[l115a3]

Re: Bumping shoulders, how do you know?

RCBS Precision Mic is fine for me. I also has s Redding Instant Indicator but just lazy to change because I use Single Stage for reloading rifle bullet.

 

[ksthomas]

Re: Bumping shoulders, how do you know?

Nice set up! I've been using nearly the exact same thing on my Dillon, right down to the Whidden tool head and Instant Indicator to verify my shoulder bump.

 

[leadbullet]

Re: Bumping shoulders, how do you know?

I don't know about the pros and cons of all this above but I usually set up my resizing die enough to be able to close the bolt with ease by slowly screwing the die down by samll increment until goal is achieved. it doesn't matter if it is .001 ot .003 shoulder push back as long as they are all the same, consistency is key to accuracy, not how many thousands the shoulder is pushed back.
hope this helps.

 

[leadbullet]

Re: Bumping shoulders, how do you know?

I don't know about the pros and cons of all this above but I usually set up my resizing die enough to be able to close the bolt with ease by slowly screwing the die down by small increment until goal is achieved. It doesn't matter if it is .001 ot .003 shoulder push back as long as they are all the same, consistency is key to accuracy, not how many thousands the shoulder is pushed back.
hope this helps.

 

[FLIGHT762]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body">Does it really matter how much you are bumping your cases?
The case needs to rechamber in your gun, set the die accordingly. If it is bumped "001" or ", 005" it still needed to be done.
Tools are neat, but not always needed. Does the guy bumping "0005" have more accurate ammo than you bumping "003"? I think not.. There is more to it.
<span style="color: #000099"> Bumping back .001" or .005" won't make a difference, but if your die bumped back .010-.020" it does make a difference, case head separations. Over the years, I've had case head separations all due to RCBS and Dillon dies that set the shoulders back way too far. A .338 Winchester Magnum that separated after 3 firings, a 6MM Remington that separated after a few firings and a .222 Remington that separated on the first firing. I had to scrap the cases.

These dies were all able to over size the shoulders when setting the dies up as instructed by the die manufacturer. All of this could have been prevented with the use of a gauge.</span>


My advice is to skip on the gadgets and buy bullets and brass, load them and shoot. Save the gadget buying until you are older, then it will be a neat conversation piece for happy hour with your buddies. <span style="color: #000099"> Well, Im the older guy your referencing here, been reloading for about 40 years, made a number of resizing mistakes over the years. I do know I'm a bit wiser now with the use of a gauge. </span> No one, even your gun gives a flying fuck how much the shoulder was bumped. <span style="color: #000099"> The rifle will care if your die is capable of too much bump. I was given a batch of 300 Winchester Magnum brass that had been F/L resized buy an unknown source. When I used my gauge to check to see how far the shoulder was bumped, the gauge indicated the shoulders somehow, had been bumped .025"too far back. Yes, no shit. I can Imagine if I would have just loaded these cases up with full power loads and touched them off.</span>

I have two fully custom guns that need the shoulder bumped every firing, and they shoot, so don't complicate matters. </div></div>

<span style="color: #000099">Weather you use the RCBS precision mic, the Innovative Technologies gauge, the Wilson/Dillon drop in gauges, or the Hornady/ Sinclair gauges, they will at least reference what your F/L dies are doing.

Personally, I prefer the Hornady/Sinclair bump gauges since they are inexpensive and can be used on a variety of cases/calibers. You use them with a digital caliper and you can see the numbers.

If you don't want to use gauges, that's your choice, but they will show you the problem if you have a chambering issue.

It seems every few days,this reloading forum gets a lot of F/l sizing questions. Most regarding not being able to chamber because not enough shoulder bump/sizing. A gauge is a good indicator of what the problem is.</span>

 

[NoFail]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body"> Does the guy bumping "0005" have more accurate ammo than you bumping "003"? </div></div>


After the experiment, I did some math on the pressure exerted on the lever and the case wall diameter and found that you are exerting pressures equal to the 48K PSI youngs modulous of the brass. That is, you exert enough force, and because the cae walls are thiin, there is enoughpressure for the brass to actually flow. If the brass does not flow, it will return to its original position. </div></div>

It was explained to me before that the brass, under all that pressure during re-sizing, actually becomes "molten". Hence it flows out towards the neck, I believe, or does it? It's why we have to trim?

 

[NoFail]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: attherange</div><div class="ubbcode-body">I don't know about the pros and cons of all this above but I usually set up my resizing die enough to be able to close the bolt with ease by slowly screwing the die down by samll increment until goal is achieved. it doesn't matter if it is .001 ot .003 shoulder push back as long as they are all the same, consistency is key to accuracy, not how many thousands the shoulder is pushed back.
hope this helps. </div></div>

And this is where I am at with neck tension. Although this is consistent coming out of the Forster FL, it is too light for use in a semi auto. After a few firings the Win brass in the neck gets less gripy @ .002". I'm going to range this afternoon with bullets seated into .002" neck tension to shoot out of .308AR.

This time I'm not shooting from mag. but will single feed by hand. I want to see if makes difference in groups. And before I load anymore I'll polish down the sizing ball a little more for .003" neck tension.

The head space I'll take the easy advise here first, that do it all comparator tool looks really cool and geaky, but cost prohibitive for me right now. I am comforted to know that the head space is consistent just by use of the Dillon head space gauge. The sized brass fits in that gauge with the heads just about a brunette vag hair below the top shelf of gauge.

 

[pmclaine]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NoFail</div><div class="ubbcode-body">The sized brass fits in that gauge with the heads just about a brunette vag hair below the top shelf of gauge. </div></div>

Be sure you do not hit the tolerance of a dark black, coarse 1970's era Vag hair or you will risk out of battery firing should these rounds go through a floating pin semi.

The next generation of reloaders is screwed because with all that shaved poon out there now they will have no reference for sizing their cases.

Its a shame one of my favorite measurements "the CH" will probably disappear from the Websters dictionary before long.

Be safe.

 

[NoFail]

Re: Bumping shoulders, how do you know?

^ yes I know what u'r saying. They are easily within SAAMI spec.

 

[YAOG]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: avidflyer</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuiggyB</div><div class="ubbcode-body">This one works for any cartridge you will load, with any shoulder angle.

http://www.larrywillis.com/

</div></div>

I have one....its ok but not great ,you need to position it the same way all of time (of course as with any tool). point is it can be hard to use and the top adjustment is set with a set screw...going to mod mine to a shell holder for the bottom and a compairitor on top that I can switch out for cases, bullets etc... </div></div>

I found the same issues you had with this gauge and thought the same thing. I would screw an insert holder into the end of the dial indicator and use Sinclair or Hornady type inserts to measure shoulder datum line and bullet ogive. But this would still not be as repeatable as the Redding Instant comparator because the case is well supported like the Redding Competition seater.

 

[YAOG]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuiggyB</div><div class="ubbcode-body">This one works for any cartridge you will load, with any shoulder angle.

http://www.larrywillis.com/

</div></div>

I don't care that the Redding Instant Comparator is designed for use with a single cartridge I want 100% repeatable and reliable measurement. With the Redding Instant Comparator I get repeatable measurements to better than 0.0005" every time even using a couple of only modest quality dial indicators.

When I set the sizing die up to set the shoulder back I KNOW it is set correctly because I can measure it 100% reliably. I don't have to take multiple measurements or fiddle with the gauge. I place the case to be inspected into the comparator station of my Dillon 550 and with a single stroke of the press lever I can see the results at a glance. I can make the same measurement 10 times using the same case and get the same reading every time.

O.K. the Redding Instant Comparator is not perfect out of the box. I did have to modify it slightly to reliably hold the dial indicator in exactly the same place because the collar with the location thumbscrew is oversize and allows too much movement to get 100% repeatable measurement. But once this minor fix is done the Redding Comparator is capable of taking extremely consistent and repeatable measurements.

 

[YAOG]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Golfy Sniper</div><div class="ubbcode-body">RCBS Precision Mic is fine for me. I also has s Redding Instant Indicator but just lazy to change because I use Single Stage for reloading rifle bullet. </div></div>

My solution for you is to buy the cheap open "C" frame press from Lee for $28 and mount the Redding Instant Comparator so it is always available for use no matter what your primary press is doing. This also allows you to set your sizing dies for exactly the right headspace.

HTH!

 

[afrancke]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Golfy Sniper</div><div class="ubbcode-body">RCBS Precision Mic is fine for me. </div></div>

RCBS Precision Mic is an excellent solution. Buy one of these first, OP, and give it a try.

By the way, one thing you may come to understand once you start using your RCBS Precision Mic is that your shoulders aren't all getting bumped evenly. In my experience, "set it and forget it" is possible with a sizing die, but the critical variable is case lubrication. Uneven lubrication will result in sizing that can differ by several thousandths for some cases. The mic is good for figuring out that, too - and experimenting with lubing techniques that will give you more consistency.

 

[71firebird400]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: avidflyer</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuiggyB</div><div class="ubbcode-body">This one works for any cartridge you will load, with any shoulder angle.

http://www.larrywillis.com/

</div></div>

I have one....its ok but not great ,you need to position it the same way all of time (of course as with any tool). point is it can be hard to use and the top adjustment is set with a set screw...going to mod mine to a shell holder for the bottom and a compairitor on top that I can switch out for cases, bullets etc... </div></div>

I found the same issues you had with this gauge and thought the same thing. I would screw an insert holder into the end of the dial indicator and use Sinclair or Hornady type inserts to measure shoulder datum line and bullet ogive. But this would still not be as repeatable as the Redding Instant comparator because the case is well supported like the Redding Competition seater.

</div></div>

I use this gauge and have found it pretty simple to get repeatable measurements, but then again I set up my dies once and am not measuring every case.

 

[turbo54]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body">Does it really matter how much you are bumping your cases?</div></div>

Yes.

If you only shoot a boltgun from the bench on sunny days, you can use the "bolt closure resistance" method of setting up sizing dies.

If you take your rifle out in the field and are subject to field conditions, and still want reliable ammo, you'll need to actually SIZE your brass a bit.

Without tools, you're guessing on how far you've set the shoulder back. Too much results in caseweb stretch, which will result in a CHS, which can give you a faceful of hot, flaming gas.

 

[YAOG]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: milo-2</div><div class="ubbcode-body">Does it really matter how much you are bumping your cases?</div></div>

Yes.

If you only shoot a boltgun from the bench on sunny days, you can use the "bolt closure resistance" method of setting up sizing dies.

If you take your rifle out in the field and are subject to field conditions, and still want reliable ammo, you'll need to actually SIZE your brass a bit.

Without tools, you're guessing on how far you've set the shoulder back. Too much results in caseweb stretch, which will result in a CHS, which can give you a faceful of hot, flaming gas. </div></div>

^^^
^^^
^^^
This!

 

[YAOG]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: afrancke</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Golfy Sniper</div><div class="ubbcode-body">RCBS Precision Mic is fine for me. </div></div>

RCBS Precision Mic is an excellent solution. Buy one of these first, OP, and give it a try.

By the way, one thing you may come to understand once you start using your RCBS Precision Mic is that your shoulders aren't all getting bumped evenly. In my experience, "set it and forget it" is possible with a sizing die, but the critical variable is case lubrication. Uneven lubrication will result in sizing that can differ by several thousandths for some cases. The mic is good for figuring out that, too - and experimenting with lubing techniques that will give you more consistency. </div></div>
This is very true. The last bit I found to sizing my cases to exactly the same dimensions was lube. I have to say the problem was solved once I tried Imperial sizing wax. Extremely slippery under pressure and allows for extremely consistent case processing.

 

[NoFail]

Re: Bumping shoulders, how do you know?

Yeah all this.... I know this from what just the Dillon gauge shows. And it think the lube probably is the culprit. But I don't know how to cure that. I don't think I use it excessively.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: YAOG</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: afrancke</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Golfy Sniper</div><div class="ubbcode-body">RCBS Precision Mic is fine for me. </div></div>

RCBS Precision Mic is an excellent solution. Buy one of these first, OP, and give it a try.

By the way, one thing you may come to understand once you start using your RCBS Precision Mic is that your shoulders aren't all getting bumped evenly. In my experience, "set it and forget it" is possible with a sizing die, but the critical variable is case lubrication. Uneven lubrication will result in sizing that can differ by several thousandths for some cases. The mic is good for figuring out that, too - and experimenting with lubing techniques that will give you more consistency. </div></div>
This is very true. The last bit I found to sizing my cases to exactly the same dimensions was lube. I have to say the problem was solved once I tried Imperial sizing wax. Extremely slippery under pressure and allows for extremely consistent case processing.

</div></div>

 

[afrancke]

Re: Bumping shoulders, how do you know?

In my experience it's not excessive lube that causes the problem (of insufficiently bumped brass) but rather not enough lube. I think the books and web forums are full of warnings about the consequence of too much lube denting cases via hydraulic pressure, so people pay attention and apply sparingly (at first, anyway), but I really think there aren't enough warnings about insufficient lube.

First, there's the newbie mistake of getting a case stuck. That one's hard to miss - you don't need a case length gauge to tell you it's happend! And nobody sets out to do it - but those warnings about what will happen with too much lube leave an impression, so people starting out (myself included, several times!) still get stuck cases. Second, even just enough lube to prevent stuck cases may not be enough to really allow even sizing, but not everybody notices because not everyone measures.

Imperial works well enough if you apply enough. If you don't, I don't think it's a panacea. My stuck cases mentioned above were all using Imperial - and I still use it (just a lot more these days, especially for the first few cases through the die).

 

[knight_dive]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NoFail</div><div class="ubbcode-body">It was explained to me before that the brass, under all that pressure during re-sizing, actually becomes "molten". Hence it flows out towards the neck, I believe, or does it? It's why we have to trim? </div></div>


I used to build deep draw stamping dies for a sheet metal shop and that is a pretty good description. The material isn't "molten" exactly, but under extreme pressure some metals will behave like a very thick liquid and flow, i.e. molecules will slide past each other and "freeze" in their new position when pressure is removed. That's part of the reason that cases "grow" when they are sized, and is the reason cases can be made from what is basically a small chunk of brass bar. The downside is that the material work hardens and becomes less willing to flow each time pressure is reapplied, hence the benefit of annealing.

 

[NoFail]

Re: Bumping shoulders, how do you know?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: afrancke</div><div class="ubbcode-body">In my experience it's not excessive lube that causes the problem (of insufficiently bumped brass) but rather not enough lube. I think the books and web forums are full of warnings about the consequence of too much lube denting cases via hydraulic pressure, so people pay attention and apply sparingly (at first, anyway), but I really think there aren't enough warnings about insufficient lube.

First, there's the newbie mistake of getting a case stuck. That one's hard to miss - you don't need a case length gauge to tell you it's happend! And nobody sets out to do it - but those warnings about what will happen with too much lube leave an impression, so people starting out (myself included, several times!) still get stuck cases. Second, even just enough lube to prevent stuck cases may not be enough to really allow even sizing, but not everybody notices because not everyone measures.

Imperial works well enough if you apply enough. If you don't, I don't think it's a panacea. My stuck cases mentioned above were all using Imperial - and I still use it (just a lot more these days, especially for the first few cases through the die). </div></div>

Well could be, I'm open to this. I got a midway order in yesterday and had some spray on lube in there (Frankford Arsenal Case Lube). I was trying to use sparingly today sizing some brass. A few times as I was bringing down the lever I had to abort and lift up before possible stuck case, I'm sure you guys know what that is like. But I resprayed them second time really good , let set a minute, and then the next attempt they were so easy and smooth going into die and back out, easy. So I'm going to remember this post of yours, afrancke.

 

[CLICKBANGBANG]

Re: Bumping shoulders, how do you know?

Here are a few thoughts I'd leave on minimal headspacing bumping. If you are not paying attention to your headspacing, don't bother finding the lands with a specific bullet. Just full size, load the bullet seating to mag length, and go.

The shoulder being bumped back .020 (like with some sizing dies and chamber sizes), and the bullet being set .005 off the lands is counter productive. When the firing pin hits the primer the bullet is just being shoved into the lands and the primer ignites. As the pouder burn happens, the bullet is already into the lands as the brass moves back in the chamber to fill and seal the chamber. When this happens, the bullet never "jumps" to the lands. It is stuck there and is forced forwards. This is fine for a load bein worked up (with the headspacing minimally bumped) for a zero bullet jump, or for a .005 positive jam into the lands.

If you are sizing the neck and only bumping the shoulder a few thousands, then finding the lands with a specific bullet is benificial. With a .002 bump on the shoulder, and a .005 jump to the lands from the bullet, you have productive time spent on developing the measurements for this chamber and the load.

Also with just bumping the shoulder a few thousands, it centers the bullet in the chamber square to the lands and barrel. Again it is counter productive to set the bullet perfectly strait with the cartridge if the brass is being full length sized. There is enough "slop" in the cartridge (when brass is full length sized) inside the chamber to not hold the bullet centerline center with the bore.

I would highly recommend the Honady Headspace Gauge, Bullet Comparator, and the OAL Gauge. With the three gauges, an some fired brass, and the bullet your going to be loading, you can work up the sizing specs of your chamber and set your sizing die to bump the shoulder your desired amount. These will also tell you how far or close to the lands you are with the bullet. With the proper tools, your time is better spent developing a load because you're not guessing on what your chamber, brass, and land distance measurements are.