.308 sooted case necks

[clay_breaker]

I searched for this topic but came up empty. I have been shooting a .308 load of 46.6 Varget with a 155 Scenar in a Rem LTR with great results, but I noticed that the necks are sooted. No visible signs of overpressure. What does this mean? These cases are neck sized only. Also shooting them with a suppressor, would that cause this somehow? I know shooting my autos suppressed always leaves everything black, but never noticed this in bolt guns.

 

[kraigWY]

Re: .308 sooted case necks

Means there isnt enough presure to seal the case (neck area).

It dosn't hurt anything, if the rounds shoot, don't worry about it.

 

[clay_breaker]

Re: .308 sooted case necks

This load shoots well. I just had not run into that before, or I never noticed it.

 

[ChrisGarrett]

Re: .308 sooted case necks

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: clay_breaker</div><div class="ubbcode-body">This load shoots well. I just had not run into that before, or I never noticed it. </div></div>

Let your neck lengths grow a few thousandths longer and see if they don't seal better.

If you're trimming to 2.005", see what 2.010" does, or if you're at 2.007", go 2.011".

Chris

 

[Shady_Jay]

Re: .308 sooted case necks

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">Means there isnt enough presure to seal the case (neck area).

It dosn't hurt anything, if the rounds shoot, don't worry about it. </div></div>

this

 

[vman]

Re: .308 sooted case necks

Yeh I get em as well.... pffffff

Dont let it stress you

 

[cmh2007]

Re: .308 sooted case necks

would that possibly cause a drop in velocity from what the book states?

 

[leadbullet]

Re: .308 sooted case necks

dirty brass is what case tumblers are for, if the load is accurate who care if the case get dirty, it isn't jewelry.
cheers.

 

[Greg Langelius *]

Re: .308 sooted case necks

Neck soot is customary. It is a consequence of incomplete or delayed neck expansion. Typically, sources trace down to either low pressure, or hardened brass. If this does not happen with new brass, the issue is not pressure. As older brass (necks) are fired/resized repeatedly, the brass work hardens, and expansion becomes less reliable. As stated above this is one of the reasons we tumble our brass, and not typically a serious issue unless it is accompanied by other issues.

Greg

 

[Leaddog]

Re: .308 sooted case necks

This is typical of reloaded ammo. Nothing to worry about unless it is excessive.

That's a hot load you are shooting. You won't be able to get away with just neck sizing for very long. Have you noticed some of the rounds to be tight when chambering yet?

 

[tomme boy]

Re: .308 sooted case necks

What is your OAL? Try seating a little deeper to help raise the PSI a little before the bullet leaves the case. I have seen this on a barrel with a realy long throat and using a bullet that was really short. Short as having a small bearing surface to length.

Also have taken care of another one by lowering powder and using a mag primer to get the PSI up faster.

 

[Jgoodley01]

Re: .308 sooted case necks

From my experience soot on the necks is nothing to worry about, depending on how much we are talking about. Extremely sooty necks are a sign of a loose neck chamber. If you are neck turning, your turning too much...if you aren't neck turning try some different brass with thicker neck walls. On my tight neck chambered competition rifle I turn my brass to give me an overall loaded neck diameter of .328 for a .330 neck chamber. this produces light soot down the neck to the shoulder, but none on the shoulder. See pictures below.

These are from the tight necked competition rifle.

And again the short ones are from the comp rifle, and the tall one is fired from a factory rem700 308.

If you are getting soot on the shoulder you are like most... sizing your brass too much. This will also cause the necks to have more sooting as it will take more time for the shoulder and the neck to expand to your chamber. Try setting your sizing die to your rifles chamber.

Take some well fire formed cases, atleast 3 firings on them....leave them unsized. Remove the firing pin and ejector from your bolt, place bolt in rifle, place case in chamber, close bolt enough to seat the case head under the extractor. At this point the bolt handle should not fall closed. If it does, your cases are not fire formed to your chamber. If you feel resistance in closing the bolt good, now to set your sizing die.

Unscrew your sizing die so that there is .050"(twice the thickness of matchbook cardboard) clearance between the shell holder and sizer die at the closest point of the stroke. Lube your verified fireformed case and size and repeat the process of checking in your chamber. Continue to adjust your sizer die downward until the bolt closes completely with a very slight resistance but without falling completely closed on its own. Lock the set screw on the lock nut for your sizer die and verify with a couple other cases. Then use that shell holder with that sizer die for that rifle, and no other rifle untill you verify by same method to ensure proper sizing.

By doing this you will see your accuracy increase as your case will be better aligned in the chamber, and as a side benefit...less soot.

 

[Jgoodley01]

Re: .308 sooted case necks

Clay, by the way I just noticed your in gainesville. I live in Valley View and if you need anything shoot me a pm...i'd be glad to help.

 

[clay_breaker]

Re: .308 sooted case necks

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jgoodley01</div><div class="ubbcode-body">Clay, by the way I just noticed your in gainesville. I live in Valley View and if you need anything shoot me a pm...i'd be glad to help. </div></div>

Thanks J, Heck, Valley View, we are practically neighbors.

 

[Fuzzball]

Re: .308 sooted case necks

"... the necks are sooted. No visible signs of overpressure. What does this mean?"

It means there was brief fire in the chamber. Really.

No matter the ingniton or peak pressure, the pressure falls pretty quickly when the bullet exits and I suspect some, maybe all, of the neck 'blow back' you see occurs at that time.

 

[diriel]

Re: .308 sooted case necks

Another potential cause for neck sooting is when the brass has work hardened. I get that some times on Known Good loads when I have neglected to anneal the cases.

Gary

 

[clay_breaker]

Re: .308 sooted case necks

This brass is on its 3rd loading, Full sized 1st time, then neck sized. Would that be enough to work harden it? This is all Hornady brass from a case 155 A'max's I shot.

 

[clay_breaker]

Re: .308 sooted case necks

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: tomme boy</div><div class="ubbcode-body">What is your OAL? Try seating a little deeper to help raise the PSI a little before the bullet leaves the case. I have seen this on a barrel with a realy long throat and using a bullet that was really short. Short as having a small bearing surface to length.

Also have taken care of another one by lowering powder and using a mag primer to get the PSI up faster. </div></div>

Sorry did'nt answer your question. These were all seated to OAL of 2.805. 155 scenar is a long bullet.

I just noticed you sig line tomme. I have a 5 yr blk lab now, best dog I have ever been associated with, much less owned. Real pheasant finding machine, wouldnt take for her.