soot on base of cartridge?

[songdogslayer]

Shooters,

I'm working up some 70 grain Nosler Ballistic Tips for my son's .243 and I'm using FL sized brass. After firing, there is substantial soot on the base of the fired cartridge - similar to the black residue found on the case neck except the soot on the base is easily wiped off. No pressure signs on the primers or necks. What's up with the soot?

Thanks gang,
~Scott

 

[brfun]

A couple of things come to mind. The first I am assuming you would have noticed a crack in the case from a partial head separation. The second is to light of a load. Not enough pressure being built to seal the case to the chamber resulting in soot down the body of the case.
Brian

 

[treeman]

sds,Is the soot on the side of the base or on the flat end where the primer goes?treeman

 

[songdogslayer]

Thank you for the replies.

brfun . . . no crack in the case. the load I'm starting with is 80% of max. The velocity was slow through the chrony, however. you may be on to something here . . . I'm thinking about pushing the bullet .010 into the lands and trying again,I was loading to C.O.A.L. specified by the book).

treeman . . . soot is on the base - over and around entire area surrounding the primer, but not going up the case walls.

Thanks again for the replies. Please let me know if there's something else . . .

~Scott

 

[Akbushape]

That sounds like a gas leak around the primer. Are the primer
pockets clean. Do the primers fit snug. How many times has the brass been reloaded.

 

[brfun]

I to agree with the primer pocket leaking. I had misunderstood where the soot was exactly in the original post as was thinking it was around the the case not on the head.
Brian

 

[songdogslayer]

OK, this is 'F C' brass and that may be all the information we need. The brass is, now, three times fired. All of my brass gets flash hole deburring and primer pocket uniformer treatment before the first reload and I use a primer pocket brush before each subsequent reload. This is the end for all of my Federal brass . . . Unless someone can tell me why I should continue running this stuff through my varmint rifle, it's getting the "destroy and throw away" treatment.
Thank you, again, for your insight.
~Scott

 

[MarkS]

Scott,

If you are F/L sizing hard down down on the shell holder, you may be creating excessive head space,too much room in the chamber). With a mim size Die and a Max chamber, and could lead to head separation. Each firing you are starting over, and refireforming the case. The case would be loose in the chamber, for every firing.

I set my F/L just to set the shoulder back 0.001" to 0.002". You could back the die off, resize only until the bolt closes eazy, not taking it to full F/L sized. or use a neck size die only.

You could screw the F/L die down just enough to size the neck only, and give it a try. It may clear thing up.



80% may be a very low starting point and could be low pressure.

Mark Schronce

 

[songdogslayer]

Thank you, Mark. I will give that a try . . . I'm hoping I don't have to throw out nearly 200 pcs of brass . . .
~Scott

 

[Akbushape]

But don't toss the brass until you know what the problem is.
You said there is no sign of excessive pressure so I'd be inclined to think it's not from the light charge, but that is
easy to rule out. Head space is a likely source as the primer may slip out slightly and then be reseated as the brass hits the
bolt face. if you have a good gunsmith take a few cases to him
and get him to inspect them for damage.

 

[songdogslayer]

Lynn,
Thank you for your insight - as I keep saying, this site rules. I really appreciate the members replying to my questions and sharing their hard-earned knowledge with me.

This is a .243, so I'm using large rifle primers . . . but I understand your point. I've taken a very close look at this brass & the primers,haven't knocked the primers out of them yet - still inspecting) and I see no pressure signs on the primers, or the brass. The primers are not flattened, they are not "bug-eyed" around the firinng pin indentation. The only sign of trouble is the soot.

Here's my plan:
1. follow Mark's advice regarding the FL sizing. One thing about FL sizing . . . I have two .243s and I segregate the brass, obviously, so I usually Neck Size. However, this FC brass was originally fired in my BVSS and now I'm putting it through the Model 11 - which means, of course, I have to FL size it.
2. allocate some factory rounds per Lynn's suggestion & run several through the Model 11 then inspect. ,BTW, I've never run factory rounds through the Model 11)
3. allocate CCI primers per Lynn's suggestion before loading any more FC brass.
4. shovel myself out of my house . . . AGAIN.

Thanks shooters!
~Scott

 

[Elkbane]

If you have two .243's and they are both Savages,and assuming you are using the same dies for both rifles, I'd set the headspace the same on both rifles to eliminate one source of variation and frustration. Set them both tight on the same "go Guage", then set your dies for minimum,like 1-2 thou) shoulder bump and you can rule excessive headspace ot of the equation. And when you need to F/L size for either gun, you won't have to mess with ruining your die settings.
Elkbane

 

[tillroot1]

This may or may not be related. But recently I had problems with this very subject, it ended up being not enough bullet in the case to seal it to the chamber and it sooted all the way back to the boltface. Causing loss of velocity and all sorts of probelms. I changed bullets and used a longer bearing surface to cure the problem by seating them further into the case. Good luck, Ron Tilley

 

[britz]

This may or may not be related. But recently I had problems with this very subject, it ended up being not enough bullet in the case to seal it to the chamber and it sooted all the way back to the boltface. Causing loss of velocity and all sorts of probelms. I changed bullets and used a longer bearing surface to cure the problem by seating them further into the case. Good luck, Ron Tilley

As soon as I started reading this thread this was exactly what came to mind. I had the same problem w/ a 300wsm, light charge of powder and 110 gr vmax's with a minimum seat in the case. The cases came out full of soot and there was no other pressure signs. I seated the rest of the bullets farther in and problem solved. The bullet was popping out of the case before the pressure sealed the case to the sides of the chamber and some gases were leaking out around the case causing very ununiform ignission.

As others have said, a loose primer pocket will lead to leakage.

 

[songdogslayer]

Thank you, folks, for all the input. I'm satisfied that the leak is likely coming from the primer pocket, as there is no soot on the case other than the neck,as with all fired rounds) and on the base of the cartridge - on top of and around the primer. The soot on the base is easily wiped away - unlike the black residue around the neck.
britz - your description is different than mine - you had soot all over the cartridge case, correct?
lynn - I did the stupid thing and wiped the soot off all of the cartridge bases while inspecting them . . . I guess I should have left a couple alone and taken pictures! If it happens again,and let us hope it does not) I'll post pictures. Thank you for taking the time to update your earlier message - I truly appreciate your help.
I bought a box of 80 grain Winchester ammo for this .243 yesterday and plan on running a few of them through the rifle today. I'm betting there will be no signs of trouble, but if there are any signs I will be a very unhappy fella.
As usual, shooters, I thank you all for your feedback. Happy New Year to everyone!
~Scott

 

[songdogslayer]

Project complete; outcome satisfactory.
Lynn, I put a few Winchester 80 grain bullets through the .243 and there were zero signs of trouble. ,and the rounds shot pretty decent, too).
Loaded up several different charges of varget pushing the 70 grain Nosler Ballistic Tips and they all shot well. The only difference in these loads was COL - I loaded .010 out of the lands. Same brass, same primers,I just HAD to try it again), same powder, etc. etc.
Anyhow, I've settled on 41.5 grains of Varget pushing the 70 grain pill. I didn't use the chrony - was snowing again - but the muz vel is likely around 3600 fps or darn close. Shooting 4 rounds inside a quarter,as in $0.25 cent piece) at 100 yards, and that's satisfactory for this rifle,varmint rig).
All the best in 2009!
~Scott