Neck Stretching FL Die

[DustBuster]

Hi Guys and Gals,

I went to town on 100 cases, then realized maybe I’m squishing them down more than really I should.

Ive read now thousands of words about this subject here and elsewhere.  My necks on .308 pmc were stretching .0085-.0095 average; lubing the inside of necks and had the die set to 1/4- turn past contact with shell holder.  The I decide to investigate about the large neck stretching.  Last night I experimented by turning the RCBS die counter clockwise. I made myself a comparator for measurement close to the shoulder datum and began to experiment.  I finally got it so instead of bumping the shoulder back .007+ (1/4 turn on die past contact), I was getting (-.003).   Before I stopped at that I even got it down to only -.001 shoulder setback). I measured the over all growth each and every time and the brass growth was ALWAYS large, 0.0085 no matter what.  Heavier lube on inside and outside of neck, slow pull out of ball thingy in neck.

Seems like varying shoulder set back on these PMC cases does not matter as far as brass growth.  Should I stay at -.003 setback from Once fire formed pmc brass?  I was Factory ammo to start with on those cases.  The factory setback vs fireform was about the same as my initial die setup( -.007+) 

It seems strange to me that varying shoulder setback did nothing for size increase of brass.  Maybe all that it might change for me is accuracy +- or chambering issues.

Edited November 9, 2021 by DustBuster

[shaffe48]

You will get more case life minimally sizing as long as you get reliability.  I would see if your .003 bump works reliably in your rifle.

Trim your cases (as necessary) after sizing.  When the fl die squeezes the case the brass needs to go somewhere...and this squeezing action includes more than just the shoulder set back.

[DustBuster]

3 hours ago, shaffe48 said:

You will get more case life minimally sizing as long as you get reliability.  I would see if your .003 bump works reliably in your rifle.

Trim your cases (as necessary) after sizing.  When the fl die squeezes the case the brass needs to go somewhere...and this squeezing action includes more than just the shoulder set back.

Yep, thank you Shaffe... I will have to make up a dummy round and see if it at least chambers ok.  You are right that the neck growth is from the whole sizing process, decreasing the diameter of everything and is not just due to any setback.  

My home made comparator measures from just a bit too far back on the shoulder, according to minimum Sammi for 308 cartridges( 1.634 -.007) Mine measures from 1.624.  I don’t think this matters too much for what I’m comparing... but I think I will make another one and try not to exceed the .400 diameter at all.

Take Care

Edited November 10, 2021 by DustBuster

[shaffe48]

The dummy round might be useful to see if you're measurements are off if you're inexperienced or as a future reference to set your dies.  That's if you are concerned about safety chambering a live round.  It would potentially have to be primed to be accurate.

 

The reason a dummy round wouldn't be all that useful is because if you have problems chambering a round it will probably be because of one of your reloads being a bit off what you intended or because of debris or rust in your chamber.  The closer you size your brass the higher odds you have of this happening.

[392heminut]

Minimal shoulder setback will only work if the reloads are only being shot in one and only one rifle, you would most likely run into chambering issues if you tried to use them in another rifle. The only real benefit to setting your die for minimal shoulder setback is for accuracy, like long range accuracy! It's not a recommended practice for semiauto rifles either, it's mostly done for target style bolt action rifles where tight chambering isn't an issue. If you decide to go to this trouble, don't be surprised if you start having issues with you bolt not closing all the way on you AR type rifle!

As you've already seen, minimizing shoulder setback really doesn't have an effect on case overall length stretching. That is because the stretching takes place at the base of the case, just in front of the case head. Nothing you can do about it, it's just how things are with shouldered cases.

Once again, you are nitpicking at something that is not going to really get you any gains, but you do you.

[shaffe48]

I'm not sure if case sizing is a primary determinant of accuracy but tailoring loads to individual guns certainly is so if you are loading to accuracy then having different loads for different guns is already a given.  If you have a accurate load you want to use in multiple guns then I would size based on the smallest chamber.

 

It's all a matter of degrees.  It's a common reloading adage that 'excessive' headspace causes case head separation and the relevant measurement is to the shoulder not the trim length of the case. 

Also while we think of sizing shoulder bump at the front of the case, expansion during firing happens at the case web at the rear.  Why?  Because ,upon firing, the pin jams the cartridge forward until the shoulder contacts the chamber.  The brass then expands rearward into the bolt face to about whatever distance you bumped the shoulder on the case.  Hence why case stretch in the webbing is directly related to shoulder bump.

.003 is not all that close and is commonly recommended for semi automatics.  .002 for bolts.  Shorter perhaps for more precise reloaders. I'm also tempted at times to just screw the die against the shell holder and run with it.  Not optimal but it obviously works.

[392heminut]

37 minutes ago, shaffe48 said:

 I'm also tempted at times to just screw the die against the shell holder and run with it.  Not optimal but it obviously works.

It's been working for me for over 40 years. Funny thing is, I've never had a case head separation in all that time! Go figure.

Edited November 10, 2021 by 392heminut

[shaffe48]

2 hours ago, 392heminut said:

It's been working for me for over 40 years. Funny thing is, I've never had a case head separation in all that time! Go figure.

Then why do you eventually pitch your brass?  Mine dont separate because I check with a paper clip and they get retired before they risk doing so.

 

[98Z5V]

20 minutes ago, shaffe48 said:

Then why do you eventually pitch your brass? 

 

I only have to toss mine when the primer pockets get loose.  That's the only reason I stop using brass.  I don't have any other issues with my brass, like case head separation or split necks.  It's just because of the way I do my loading. 

3 hours ago, shaffe48 said:

I'm also tempted at times to just screw the die against the shell holder and run with it.

This is exactly what I do on guns that I only have one of.  The .300Win Mag, .260 Rem, .338 Fed, 25/45 Sharps, etc. I put the case in the shell holder, run the ram up, and screw the die down until it touches the case firmly.  Almost no bump.  Doesn't need it - it's already chamber-sized.

Edited November 11, 2021 by 98Z5V

[DustBuster]

Good to hear from you experts.

I made up a a couple of dummy rounds .003 under my fireformed brass, and they loaded and ejected without problem.  I think they were even sized based on one of the smallest of my my fireformed samples.   I think my 0.003 sized shoulder length is barely to the minimum of saami cartridge spec... 1.627”. I’m not concerned about sizing for better accuracy, more so for just finding the best overall way to do it for this one gun.  I measured some of the cases I sized originally and they were .009 set back from the fireformed cartridge, which seemed a little much.  I suppose the fireformed brass weren’t even totally tight in the chamber yet having been only used once.  A little extra safety tolerance in there for this newbie as I’m learning.

I like the sound of 98s method.  Using the brass in the shell holder to set the die.  Similar to what the bullet seating instructions tell me to do.

Damn daylight savings, which now prevents me from getting out to shoot after work.  It’ll be awhile before I can test out my range of loads.

Happy Veterans Day tomorrow to you Noble Warriors

Edited November 11, 2021 by DustBuster

[shaffe48]

I'm not an expert but what you are doing is generally what the experts recommend as the 'best' 'optimal' way.  

 

As others noted you can probably get away with sizing against the shell holder without much lost unless you have a poorly headspaced chamber.

[DustBuster]

3 hours ago, shaffe48 said:

I'm not an expert but what you are doing is generally what the experts recommend as the 'best' 'optimal' way.  

 

As others noted you can probably get away with sizing against the shell holder without much lost unless you have a poorly headspaced chamber.

Yes, thank you Shaffe, and like 392Heminut stated, the brass growth is irregardless of shoulder setback.  So far I haven’t seen a difference.  Die set to the shell holder or some bit upward, doesn’t matter for the case growing and trim needs.  And since I am a long way from needing optimum Case sizing for accuracy sake, I won’t be worrying to much.

My chamber is tighter than the no-go gauge.  I’m very glad I listened to advice here and found that out.  Dealing with thousandths of an inch precision is a new world to me.  The son of my boss is taking gunsmithing courses, and he told me his beard hair was exactly 3 thousandths, he used it as a shim or something like that.  Haha

 

Edited November 11, 2021 by DustBuster

[DustBuster]

Correction to my previous statement... after thinking about it all abit more and rereading Shaffe48s statement about stretch at the casehead zone... I now realize... the lengthening of brass is not due to what shoulder position is chosen at the secondary sizing period, but has already been decided by the previous shoulder position and Firing of the round.  That is why I was not seeing a difference between the brass growth with my two different shoulder bumps.  I will need to fire the rounds again before I see a difference.   

I see it clearer now. Thanks

[392heminut]

13 hours ago, shaffe48 said:

Then why do you eventually pitch your brass?  Mine dont separate because I check with a paper clip and they get retired before they risk doing so.

 

Like 98 said, I usually pitch mine when the primer pockets get loose. I'll also occasionally pitch one with a split in the case.

Edited November 11, 2021 by 392heminut

[shaffe48]

One way to increase brass life which I most adore is to buy good brass.  Otherwise, the main culprits to brass loss and their cause/solution would probably be:

 

1.). Loose primer pockets:. Pressure

2.). Neck splits:. Annealing

3.). Case head separation:. Sizing

 

Obviously if number 1 is getting you then you might never see number 3.

 

 

 

 

 

 

 

[98Z5V]

5 hours ago, shaffe48 said:

One way to increase brass life which I most adore is to buy good brass.  Otherwise, the main culprits to brass loss and their cause/solution would probably be:

 

1.). Loose primer pockets:. Pressure

^^^Truth.  I don't load light charges.  I try to squeeze everything I can from these bastards, and make them work for it.

[DustBuster]

7 hours ago, shaffe48 said:

One way to increase brass life which I most adore is to buy good brass.  Otherwise, the main culprits to brass loss and their cause/solution would probably be:

 

1.). Loose primer pockets:. Pressure

2.). Neck splits:. Annealing

3.). Case head separation:. Sizing

 

Obviously if number 1 is getting you then you might never see number 3.

 

 

 

 

 

 

 

Interesting... I have never come across any one of those three situations yet...I’ve have not yet reloaded twice fired brass... I’ve picked a few loads out to fine tune for accuracy sake, and I’ve seen with the twice fired brass now probably what is close to my chamber size... So hopefully when I get those twice fired brass reloaded with a little less shoulder bump, I will have the best solution for any future new brass I get.  I have a WFinestTrimmer2 on the way.  I have not tried to feel with a paper clip the thinning inside the brass yet, but am curious to see if I can detect it. Thanks for your tips shaffe48.  I suppose by the time I burn through my bottles of powder I will be closer to understanding this fine art.  I hear a Tumbler in the basement going on now, but it is filled with rocks and not brass yet so I am sad.  In a few weeks I will see if I can get in on that action.

Edited November 19, 2021 by DustBuster

[DustBuster]

When I see for the first time some primer pockets big and loose I will think of your Ammo 98.  Squeezing every molecule out of those cases shooting Optimum velocity super rockets towards Arizona bullseyes....If you didn’t sleep in because of a raging campfire and whiskey PowWow

[shaffe48]

Paper clip and a small flash light.  Dim interior lights and put flashlight into neck and it'll light up splits.

[98Z5V]

22 hours ago, DustBuster said:

When I see for the first time some primer pockets big and loose I will think of your Ammo 98.  Squeezing every molecule out of those cases shooting Optimum velocity super rockets towards Arizona bullseyes....If you didn’t sleep in because of a raging campfire and whiskey PowWow

I'm just a product of my environment, man - some crazy ass Army times (and people), and the Warrior Ethos...   Work Hard, Play Hard.