Cases with a lot of soot around neck, sholder and body

[TQB]

Hi,


I switched from neck only sizing to full length sizing (FL) and I have some questions.

My set up is:

L.E. Wilson FL .308 win die.

L.E. Wilson micrometer.308 seater die

Lyman All-American Press (the old red model with turret)

An arbor press

My cases are cleaned with ultrasonic cleaner with lyman turbosonic.

The solution is getting old and some tarnish is found on the twice fired cases (first reloading).


Components:

Lapua .308 win cases

Lapua Scenar 185gn bullets

CCI BR-2 primers

Vihtavuori N140


Recipe:

39gn of Vihtavuori N140

0.0015’’ of neck tension
0.002'' of shoulder bump

CBTOL – 59.20 mm or OAL – 72,80 mm (0.020’’ to lands)


My problem is that I'm having quite more soot appear at the neck, shoulder and at some extent, sometimes at the case body.

The picture shows twice fired cases in the back (various powder weights from 38.8gn to 41.4gn) and once fired cases at the front (39gn).


The accuracy at 100m (note the upper 5 shot group at 100m)

What might be causing this? I don’t recall having this issue, at least to this extent, when I neck only sized.


Thank You,

Tiago

 

[Hohn]

How does the headspace of your loaded rounds compare to the fired cases? The chamber?

 

[XTR]

That is a very low pressure load, my 50th Lyman shows the minimum load for a 180 at 38.0 with N140.

How deep are you seating the bullets and how far are they jumping?

It looks to me like the brass isn't getting expanded well enough to seal the chamber. I've seen that before with bullets seated way out of the case with a long jump such that they moved out of the neck before pressure could seal the case against the walls.

You might try some combination of one or more of: more neck tension, seat the bullets deeper, or more powder.

Do you rinse your cases after you clean? Some of the discoloration is from the cleaning fluids.

and

If you don't anneal your necks are getting work hardened and harder to expand, though with only one firing I doubt that is an issue here.

 

[Walt Krafft]

Need mo powder.

 

[Bill Norris]

I believe she needs a little more juice.

 

[Metal God]

Yeah I’d check my chamber and bolt face as well . You are blowing crap everywhere. You are dangerously low on pressure .

 

[MagnumManiac]

I have never seen so much blow by on a case.
You are way low on pressure.
Do any of these loads hang fire?

Cheers.

 

[243winxb]

C.O.L. 71,0 mm / 2.795 inch & increase neck tension.

 

[jplahr]

Check the headspace on the sized cases. Should be .002 set back. Add more powder.

 

[JSH]

My thinking is hard brass and soft loads. I learned a fair bit shooting cast that answered some jacketed issues I had.
I have some issues with a 17 Fireball with what you describe, these are far from a soft load. I annealed a few just to see problem solved.

I have seen the past couple of months folks having cracked necks with reloaded and factory ammo that has been stored for a while. Look at it like a spring, it will
only flex so many times or for so long and something has to give.
Forget where or whom it was, one fellow only loaded his ammo if it was going to be used fairly soon. Brass will harden with age and no use just sitting. Seems to do better when sealed up away from oxygen.
One of you scientific gents will have to step in to explain.

 

[Rsadams]

Low pressure is normally the problem..... Be sure and clean the chamber well , the whole gun wouldn't hurt...

 

[carlsbad]

anneal.

 

[Texas10]

Are you shooting suppressed?

 

[Doom]

By design the brass has to have enough pressure to deform it enough to contact the chamber wall which then expands ever so slightly under the pressure resulting in a seal that is broken when the pressure is removed, commonly called springback. Without enough pressure to plasticly deform the brass the chamber can't seal.

You didn't mention if this is a bolt or a semi-automatic rifle. If it a semi-automatic (AR10) the issue could be gas system timing where too much gas is being ported back to the bolt.

 

[TQB]

Answering some questions:

- The rifle is a Bolt rifle (SAKO TRG 22)
- Fire formed headspace (measured with the Hornady Headspace comparator) - 41.25mm (1.624'')
- Recent cases (with soot) headspace - 41.22mm (1.623'')
- Sized brass headspace - 41.20mm (1.622'')
- Outer Diameter of fired cases (with soot) - 8.74mm (0.344'')
- Outer diameter of sized brass - 8.31mm (0.327'')
- I'm not using a supressor

I will try to work up a load with more powder to avoid this issue. But I'm a little sad, since this was my most acurate load yet...

Thank You,
Tiago

 

[Walt Krafft]

The 308 is very forgiving. You should have no trouble finding an accurate load with several grains more powder.

 

[243winxb]

Outer Diameter of fired cases (with soot) - 8.74mm (0.344'')
- Outer diameter of sized brass - 8.31mm (0.327'')

The fired neck diameter of .344" is close to what it should be.

Need more information on the sized .327" neck diameter.
What is a loaded rounds neck diameter?

You dont want to make the neck smaller then needed. A bushing die gives more control on how much the neck is sized .

 

[Texas10]

Suggestions:

If it shoots best at that load, stick with it. Nothing less impressive than a fast miss.

Change your cleaning solution to RCBS concentrated brass cleaner. Don't use gun parts cleaner and don't reuse cleaner. I mix a gallon batch at a time with the RCBS and keep it next to the cleaner and tumbler.

Anneal your brass often.

 

[D-4297]

I'm going to commit sacrilege by suggesting a couple of changes for your load . First ; change to a large primer brass , such as Peterson , or Barnes . My own testing w/a 185gr Berger Hybrid showed me that lower grain loads did exactly what you experienced due to not getting a full ignition of the charge , before the beginning of bullet release . The Lapua SRP brass is not conducive to a full ignition , even when using Rem 7-1/2BR primers , and changing to a LRP brass , and using the standard Winchester LRP solved the problem . The Win LRP is one of the "Hotest" LRP's out there , according to testing by the U.S. Army some years ago at Aberdeen . And that was with a .001 neck interference . Blow-back stopped at the neck / shoulder junction . Yes ! The necks did smoke up a little more than normal , but it stopped at the junction . As far as the powder load is concerned , I would suggest taking it up in .2gr increments to assist in eliminating the issue altogether , till it goes away . If you're locked-in on using SRP Brass . Though changing to LRP brass is the easier fix . Been there already , Done this .

 

[TQB]

I'm going to commit sacrilege by suggesting a couple of changes for your load . First ; change to a large primer brass , such as Peterson , or Barnes . My own testing w/a 185gr Berger Hybrid showed me that lower grain loads did exactly what you experienced due to not getting a full ignition of the charge , before the beginning of bullet release . The Lapua SRP brass is not conducive to a full ignition , even when using Rem 7-1/2BR primers , and changing to a LRP brass , and using the standard Winchester LRP solved the problem . The Win LRP is one of the "Hotest" LRP's out there , according to testing by the U.S. Army some years ago at Aberdeen . And that was with a .001 neck interference . Blow-back stopped at the neck / shoulder junction . Yes ! The necks did smoke up a little more than normal , but it stopped at the junction . As far as the powder load is concerned , I would suggest taking it up in .2gr increments to assist in eliminating the issue altogether , till it goes away . If you're locked-in on using SRP Brass . Though changing to LRP brass is the easier fix . Been there already , Done this .

The Lapua brass I'm using is Large Primer Brass.