Need some advice on 308 win loads and neck soot.

[Mr Underbridge]

Edit: I used 175gr smk, brand new unfired lapua brass
Hey folks, shot some loads out of my boom stick with great results but the necks were all covered in soot. I am wondering why, I poked around and searched forums and most people say that it is because of lower pressure but looking at my brass I dont think that that is the issue.
308 lapua brass trimmed to 2.005, FL sized used redding S bushing to set the tension. Turned the necks and my wall thickness is about 0.0141~0.0140
and I used a 0.334 bushing.
This is a palma 95 chamber, I seated my bullet 0.008" away from the rifling(rifling starts at 2.198 I placed the bullet at 2.190) measuring base to ogive.
I used cci#200 large rifle primers and 44.3 grains of varget and tried a second load with 44.5 grains of varget both were equally sooty.
Pictures:
0526151224b by petrov1983, on Flickr

0526151224 by petrov1983, on Flickr

Here are my headstampps, the one on the left is 44.3 grains of varget the one on the right is 44.5 also can some one tell me what the swipe marks on the 10 ocklock position are?
0526151225 by petrov1983, on Flickr

 

[r bose]

Swipe marks on the brass typically happen when you've gotten to the upper range of chamber pressure.

Not sure about the soot on your necks. My rifles do this also.

What weight bullet are you using? Your OAL must be off. 308 OAL is going to be at least 2.800

 

[rminut]

i'm guessing this is an AR10 rifle?

the neck size of a Palma 95 is .342

 

[Mr Underbridge]

No this is a remington 700. I am sorry I failed to mention this, the rifle seems to get cratered primers no matter which load I use.
But you can see that the primer with 44.5 grains is considerably more flattened compared to the primer with 44.3 grains
Sorry I do not know what the OAL is, I do not take that measurement I always use length to ogive as that is much more consistent.

 

[CJ6]

Swipe marks on the brass typically happen when you've gotten to the upper range of chamber pressure.

Your OAL must be off. 308 OAL is going to be at least 2.800

Probably using a "comparator" so need to take that into account (Base to ogive).

 

[hogpatrol]

Cratered primers on any load? That seems to be the norm with Remington 700s nowadays. Send your bolt to Gre-Tan for a bushing and firing pin job and unless their are other issues, those crater will be no more. As far as the headstamps marks, looks like excessive pressure.

 

[Mr Underbridge]

Is the cratering going to cause a problem down the road?
Would it be safe/acceptable to move the bullet closer to the rifling some more if it doesnt degrade accuracy?
Honestly what I need to do is probably get a better scale. I have old RCBS 505 that has not been treated well. RCBS charge master in my future but I need to drop by my local gun store and see what kind of scales they have in stock and double check my weights.

 

[jonbearman]

It appears the primers are extruding into the firing pin hole chamfer and I would get gre-tan to do his magic. How much are you bumping the shoulder back? The swipes may be from the bolt being to tight against the cartridge case from not being bumped,just a guess. Does it take a little oomph to close the bolt?

 

[Mr Underbridge]

First time firing in this rifle so I full length sized these cases.

 

[CatShooter]

Is the cratering going to cause a problem down the road?

No... those are caused by oversized firing pin holes and are nothing to worry about.

Have you annealed the necks - if they are hard, they do not seal the chamber well. That looks like the problem.

 

[DennisH]

It looks as though the soot may be caused by combustion gas escaping before the neck has sealed off.

I have experienced the above as well.

I would also anneal the necks. I didn't catch why your turning the necks, but are you able to shoot an unturned round?

Sealing is an issue. I have some, but would state it is very little.

Dennis

 

[Mr Underbridge]

Gah, another thing I failed to mention brands new unfired Lapua brass.

 

[jonbearman]

Cat I need to disagree. I thought I had pressure problems, sent my bolt to gre tan and shot it with no pressure problems or seemingly pressure problems with moderate loads. I would have it done regardless. I know it isn't dangerous but why put up with sloppy machining.

 

[CatShooter]

Cat I need to disagree. I thought I had pressure problems, sent my bolt to gre tan and shot it with no pressure problems or seemingly pressure problems with moderate loads. I would have it done regardless. I know it isn't dangerous but why put up with sloppy machining.

I am not sure what you are disagreeing about. The appearance of primers from an oversized pin hole is very different than true cratering.

I sent a bolt off to Greg Tanner, and the improvement was very little - and I would not do it again.

 

[bigedp51]

Read post # 2, from this post I'm guessing your getting soot on the necks because of your chambers neck diameter and approximately .010 neck clearance. If your necks were a cars piston and rings you're getting blowby because the rings/case neck is providing a poor seal.

95 Palma reamer
http://forum.accurateshooter.com/index.php?topic=3773531.0

The case swipes are telling you that your load is hot and the case is just starting to flow into the ejector. And my Sierra manual tells me you are loading over max.

I will also take a WAG and say you have a Remington 700 action.

I will also guess that you didn't make a workup load starting low and working up reading your cases as you went..

 

[Mr Underbridge]

I will also guess that you didn't make a workup load starting low and working up reading your cases as you went..

Yes, yes I did. My ego told me to tell you that you are a mean doo doo head
BTW when I seat my bullet there is a bit of kernel crunching, is that normal for a 44.3 grain load?

Also I am a little bit dense, so I am getting a poor seal because my cartridge neck is too thin?

And I used a hodgon manual, it says 45gr is max

 

[Comrade Terry]

No... those are caused by oversized firing pin holes and are nothing to worry about.

Have you annealed the necks - if they are hard, they do not seal the chamber well. That looks like the problem.

+1 for the annealing, CatShooter.

I've a Rem 700 in .308 that gave me sooty necks to varying degrees with all powders. Only after I started annealing after every firing did the soot problem disappear.

Edited to add: I also turn my necks just enough to clean them up. My Rem 700 .308 chamber at the neck is 'generous' in size.

 

[Mr Underbridge]

No... those are caused by oversized firing pin holes and are nothing to worry about.

Have you annealed the necks - if they are hard, they do not seal the chamber well. That looks like the problem.

+1 for the annealing, CatShooter.

I've a Rem 700 in .308 that gave me sooty necks to varying degrees with all powders. Only after I started annealing after every firing did the soot problem disappear.

This is brand new Lapua brass we are talking about.

 

[bigedp51]

Mr Underbridge

From Doo Doo Head

When I make up a work up load the case necks start with soot all over the necks and possibly down the shoulder of the case. Then as the pressure increases the soot level decreases to none or very little in a perfect world. I guessing the soot on your necks is cause by the imperfect world of a large chamber neck diameter and the fired case neck having to expand further to seal the necks. This means the soot got on the necks before they expanded fully due the your neck clearance.

The link I provided had the poster telling you he had the same problem and had soot on the necks. And if you removed too much from the necks turning them you made the problem slighly worse.

You have case head swipes on one end of your case from high pressures and soot on your necks. This tells me that you're stuck with soot on the necks with the palma 95 chamber and the brass you are using.

 

[Mr Underbridge]

That is odd considering the fact that palma chamber is actually tighter so theortically it should seal better.
I looked at my 44.3 grain loads and there are just minor marks from the ejector vs 44.5 grain load.
I am going to bump it down to 43.8 and work from there to see how it reacts.
I feel stupid, I should know better after a decade of reloading to start at a low and safe weight.