Fouling past the case neck

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JRBullock1987

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#1
Well...I am officially stumped!!!
I use the 6.5cm sac sizing die with .285" shoulder/neck bushing and .2625" expander mandrel with alpha munitions ocd LRP brass. When I shoot my zermatt origin action with proof ss prefit barrel and oss suppressor I always get a ton of fouling that goes past neck down to the bottom of the shoulder and sometimes past that. Ive tried everything to fix it and nothing works..different bushings/expander mandrels I bump the shoulder back .002". I just just got in a new batch of alpha brass and the necks on some were messed up so I ran them all through my sac sizing die that way I always to make sure my shoulder is set where it normally is (I've got a tight chamber) after i did that I went and shot some and the fouling stayed on the neck and didn't go past that onto the shoulder and further. I cant figure out what's different. Everything reloading wise is the same. gear is the same only thing difference is that's its new brass but I did resize it all before using it and with all my brass I always anneal before resizing ( not with the new brass). Can anyone tell me what the heck is happening and how I can correct it so my fouling isn't going past the necks and into my.chamber anymore. What made the new brass different even with the sizing being the same.
Thanks all,
Justin
1st pic is brass with multiple firings. 2nd is new and sized brass
 

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#4
I'll throw something against the wall and see if any stick.

1-Hard brass. I did see where you mentioned you anneal. Did you really anneal. Depending on your machine/technique, you may just be heating the brass up some.

2-Larger "neck" chamber (not likely anyway). You mentioned you had a tight chamber so not so much here.

3-Light charge on load.

4-Suppressors (much more of an issue with semi-auto and yours is a boltgun).
These "somethings" can work together to leave some smokey cases. Your fresh brass was probably softer at the neck and shoulder so a lighter charge can still get a good seal.

I have had #1 and #3 leave some fouling past the neck shoulder on bottleneck cases. If it were a straight wall case I would say #3 and die on that hill. I have shot many boxes of 140 grain Bergers (500 count) in multiple Creedmoors and my charge is a few grains north of yours and my cases never get to smokey....
 
#5
Might be able to provide more info Monday, I just sized some Hornady annealed cases with a SAC die. I used a .291 bushing with a 2620 mandrel. I’ll be shooting Sunday suppressed and will let you know. I’ll be shooting H4350, varget, and sta-bal 6.5 with cci 250 primers.
 
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#6
RG0099 said:
Might be able to provide more info Monday, I just sized some Hornady annealed cases with a SAC die. I used a .291 bushing with a 2620 mandrel. I’ll be shooting Sunday suppressed and will let you know. I’ll be shooting H4350, varget, and sta-bal 6.5 with cci 250 primers.
Click to expand...
For sure... let me know. I love their products and have tried 3 different sized expander mandrels and 4 different sized shoulder/neck bushing and no change. One thing that I thought It might have been is until recently their bushings had a slight taper in the neck-shoulder junction that they have stopped cutting into their bushing and I just got a .285 bushing that doesn't have that taper and thought that might be the difference but I sized some 3 times fired brass with it and nothing changed. I talked to sac about it and they said that there's no need to buy all new bushings without the taper cause it doesn't make a difference which is why they stopped cutting them into their bushings. Regardless I really like the quality of their products and dont get them so much for some kind of new technology.
 
#7
DHDeal said:
I'll throw something against the wall and see if any stick.

1-Hard brass. I did see where you mentioned you anneal. Did you really anneal. Depending on your machine/technique, you may just be heating the brass up some.

2-Larger "neck" chamber (not likely anyway). You mentioned you had a tight chamber so not so much here.

3-Light charge on load.

4-Suppressors (much more of an issue with semi-auto and yours is a boltgun).
These "somethings" can work together to leave some smokey cases. Your fresh brass was probably softer at the neck and shoulder so a lighter charge can still get a good seal.

I have had #1 and #3 leave some fouling past the neck shoulder on bottleneck cases. If it were a straight wall case I would say #3 and die on that hill. I have shot many boxes of 140 grain Bergers (500 count) in multiple Creedmoors and my charge is a few grains north of yours and my cases never get to smokey....
Click to expand...
I'm kind of think it might be #1 actually. Next time anneal I'll have to really make sure that the flame starts to change color before it moves on to the next one. Im new to 6.5cm. Both shooting and reloading and for a while I'd been going off load data directly from hodgdons website and their max shows like 40gr I believe for h4350 and I kept thinking...man I dont understand how ppl are getting into 2800s when I'm in the high 2600s at the supposed "max" charge weight. Come to find out that hornady shows something like 41.5grs I think for h4350. Anyways, I'll have to make sure I'm actually annealing the brass and not just barely flaming them. Ive been kinda wondering if maybe i havent been ennealing long enough. Thanks brother
 
#8
JRBullock1987 said:
Well...I am officially stumped!!!
I use the 6.5cm sac sizing die with .285" shoulder/neck bushing and .2625" expander mandrel with alpha munitions ocd LRP brass. When I shoot my zermatt origin action with proof ss prefit barrel and oss suppressor I always get a ton of fouling that goes past neck down to the bottom of the shoulder and sometimes past that. Ive tried everything to fix it and nothing works..different bushings/expander mandrels I bump the shoulder back .002". I just just got in a new batch of alpha brass and the necks on some were messed up so I ran them all through my sac sizing die that way I always to make sure my shoulder is set where it normally is (I've got a tight chamber) after i did that I went and shot some and the fouling stayed on the neck and didn't go past that onto the shoulder and further. I cant figure out what's different. Everything reloading wise is the same. gear is the same only thing difference is that's its new brass but I did resize it all before using it and with all my brass I always anneal before resizing ( not with the new brass). Can anyone tell me what the heck is happening and how I can correct it so my fouling isn't going past the necks and into my.chamber anymore. What made the new brass different even with the sizing being the same.
Thanks all,
Justin
1st pic is brass with multiple firings. 2nd is new and sized brass
Click to expand...
Well, obviously, the necks are not expanding quick enough to seal things off to prevent that from happening. I think it going to take some experimenting with different things to locate just what the issue is. I think DHDeal made some good suggestions as to what might be at issue. One need to figure out WHY your necks are not expanding quick enough. What could cause your necks to do so?

Something about the cartridge itself? Something about the chamber configuration? A combination of both?

From the description of the load you're using, it doesn't sound like it has anything to do with the load.

What I'd do to help with a diagnosis is to fire a couple factory rounds and see if you get the same results. If not, then you can discard the idea that it might be something to do with the chamber and then focus on the case attributes.
 
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#9
straightshooter1 said:
Well, obviously, the necks are not expanding quick enough to seal things off to prevent that from happening. I think it going to take some experimenting with different things to locate just what the issue is. I think DHDeal made some good suggestions as to what might be at issue. One need to figure out WHY your necks are not expanding quick enough. What could cause your necks to do so?

Something about the cartridge itself? Something about the chamber configuration? A combination of both?

From the description of the load you're using, it doesn't sound like it has anything to do with the load.

What I'd do to help with a diagnosis is to fire a couple factory rounds and see if you get the same results. It not, then you can discard the idea that it might be something to do with the chamber and then focus on the case attributes.
Click to expand...
I'm kinda thinking it might be under annealing bc new brass didnt have the issues my previously fired brass has and the only difference really would have been the softness of the brass at least that i can think of off the top of my head. it's easy to rule out anyways. Just anneal my brass a bit longer and see if there's any difference if not ill just have to keep eliminating ideas one by one. I'll have to try shooting some factory ammo as well. I Didn't even think about that. Thanks bro
 
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#10
JRBullock1987 said:
I'm kinda thinking it might be under annealing bc new brass didnt have the issues my previously fired brass has and the only difference really would have been the softness of the brass at least that i can think of off the top of my head. it's easy to rule out anyways. Just anneal my brass a bit longer and see if there's any difference if not ill just have to keep eliminating ideas one by one. I'll have to try shooting some factory ammo as well. I Didn't even think about that. Thanks bro
Click to expand...
Yes, it could be an annealing issue. You might describe your annealing details. If you're flame annealing, be sure to get the necks to start glowing red, just for a second before dropping them out of the flame. And to get there, I wouldn't think your necks would be in the flame more than 9 or 10 seconds. If that seems like a long time . . . it's really not. If you're got your flame running properly, it should only take 8-9 seconds for a 6.5cm case to get the neck to glow red IN A DARKENED room. :giggle:
 
#11
What velocities are you seeing? Are you shooting suppressed? I doubt it is annealing. More likely as stated previously:

3-Light charge on load.

4-Suppressors (much more of an issue with semi-auto and yours is a boltgun).
These "somethings" can work together to leave some smokey cases. Your fresh brass was probably softer at the neck and shoulder so a lighter charge can still get a good seal.
 
#12
First thing I'd do is bump your charge weight up .003g at a time until your velocity is 2750-2800, if the issue continues then see below, but this looks like a light charge issue to me at only 2600FPS, I shoot a BRA and bump my shoulders .004, shoot suppressed 95% of the time, I only anneal every 4-5 firings and do not have this issue.

You say your bumping shoulders .002? Are you sure its .002? and not .004-.006? Suggestion....Reset your sizing die to where it does not bump the shoulder at all and try to chamber that piece of brass if if chambers with no resistance then you are bumping your shoulders to much.
If that piece of brass is real hard to close the bolt on, or wont close, then use the same piece of brass and and slowly start turning your die down, size that piece and chamber it until you feel a slight resistance at the very bottom of the bolt close(remember a small adjustment makes a big difference)once you feel that resistance adjust your die to bump the shoulder .001-.002 more.
Then size a different piece making sure the measurement is the same then chamber it if, you feel that slight resistance bump it .001-.002 more and you should be good.
 
#16
zeroz said:
.003 grain? Guys are getting crazy in the weeds with their scales these days. You splitting kernels with a microscope? LOL.
Click to expand...
I saw that number and just discarded the two zeros he had at the front. I suspect he meant .3 of a grain.

I tend to have long barrels (26" at minimum) so I am in the 2835 fps range with hybrids or VLD's, but my charge of H4350 is higher than the OP is running. I do not remember loosing many cases to loose primer pockets. I use Hornady cases with a couple exceptions and they are not known to have the strength of Lapua. My rambling point is 2600 fps is not all this cartridge can do with a 140 grain bullet unless you have a short barrel.
 
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#17
I had a similar problem loading 155gr Berger Hybrids close to the lands in my .308. To get close to the lands the bearing surface was only around 1/8" into the neck. I suspect there wasn't enough neck tension to help the pressure build up before the bearing surface left the neck.

If the initial pressure is not enough, the neck does not expand to seal the chamber effectively. I had to seat the bullet 0.120" deeper before I had normal case expansion.

To test this theory, try to drop a bullet down the neck of a fired case.
 
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#18
JerkyFreak said:
I had a similar problem loading 155gr Berger Hybrids close to the lands in my .308. To get close to the lands the bearing surface was only around 1/8" into the neck. I suspect there wasn't enough neck tension to help the pressure build up before the bearing surface left the neck.

If the initial pressure is not enough, the neck does not expand to seal the chamber effectively. I had to seat the bullet 0.120" deeper before I had normal case expansion.

To test this theory, try to drop a bullet down the neck of a fired case.
Click to expand...

My first thought was low charge but I think that this may be the issue or lack of neck tension.
 
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#19
John Glidewell said:
What velocities are you seeing? Are you shooting suppressed? I doubt it is annealing. More likely as stated previously:

3-Light charge on load.

4-Suppressors (much more of an issue with semi-auto and yours is a boltgun).
These "somethings" can work together to leave some smokey cases. Your fresh brass was probably softer at the neck and shoulder so a lighter charge can still get a good seal.
Click to expand...
Ive gone up to 2720ish i think. I shoot suppressed.
 
#21
LR1845 said:
First thing I'd do is bump your charge weight up .003g at a time until your velocity is 2750-2800, if the issue continues then see below, but this looks like a light charge issue to me at only 2600FPS, I shoot a BRA and bump my shoulders .004, shoot suppressed 95% of the time, I only anneal every 4-5 firings and do not have this issue.

You say your bumping shoulders .002? Are you sure its .002? and not .004-.006? Suggestion....Reset your sizing die to where it does not bump the shoulder at all and try to chamber that piece of brass if if chambers with no resistance then you are bumping your shoulders to much.
If that piece of brass is real hard to close the bolt on, or wont close, then use the same piece of brass and and slowly start turning your die down, size that piece and chamber it until you feel a slight resistance at the very bottom of the bolt close(remember a small adjustment makes a big difference)once you feel that resistance adjust your die to bump the shoulder .001-.002 more.
Then size a different piece making sure the measurement is the same then chamber it if, you feel that slight resistance bump it .001-.002 more and you should be good.
Click to expand...
Yeah i use the sac comparator and measure the fired cases and average them then do .002" less. I'll have to try your suggestion. Its a great idea. Appreciate it.
 
#24
JRBullock1987 said:
Good to know thanks. So I use the sac .285 shoulder/neck bushing with the .2625" expander mandrel to get me roughly .002" neck tension after spring back. It that to large of an expander mandrel?
Click to expand...

Neck tension doesn't change the chamber pressure within reason. My preference is for a little more but a thousandth or two more won't change the sooting.

My preference is .003 to .005 of interference. Fresh annealing minimizes spring back.
 
#25
Cascade Hemi said:
Neck tension doesn't change the chamber pressure within reason. My preference is for a little more but a thousandth or two more won't change the sooting.

My preference is .003 to .005 of interference. Fresh annealing minimizes spring back.
Click to expand...
When you say interference do you mean for example a 6.5cm expander mandrel would be .261 for .003 of interference?
 
#29
Does fowling past the neck have to do with the barrel or the action? Like if I want to find a solution but have tried everything else do I need to get a new action or does it have to do with the barrel itself or maybe both? Cause I'm looking at a new barrel but im wondering if I should switch over from the origin action to the impact 737r? Eventually I want to switch over anyways but im a lefty and they are hard to find in left handed.
 
Last edited:
#30
FatBatman said:
What is the oal you load to. I have had issue like this with not enough bullet in the neck.
Click to expand...
I've not had this issue due to not enough bullet in the neck, at least . . . bit with the .308's and 6.5 PRC is load to. I tend to load long, as I start out at .010 off the lands. Often, I easily only have just .200 - .217 of the neck holding onto the bearing surface. I should mention too that I due turn my .308 cases down to .014" thick, which will help them expand a little faster.

JRBullock1987 said:
I always make sure that most if not all of the bullet is in contact with the whole neck.
Click to expand...
As long as you're not engaging the bearing surfaces with the donut area, that works just time. Because I tend to a load where the donut area is never an issue and it lessens the interference between the surface of the neck and the bullet. I haven't found any particular advantage to having a lot that contact with the neck.
 
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#31
JRBullock1987 said:
Does fowling past the neck have to do with the barrel or the action?
Click to expand...
It has nothing to do with the action. It’s a combination of your specific brass hardness, dimensions, your chamber dimensions and how you load creates pressure and burns behind the bullet.

The action may influence ignition but it doesn’t control combustion or cause sooty necks (which aren’t a problem).

Your barrel is at the mercy of your reamer. It’s just a chunk of clay in this scenario that’s molded by the chamber reamer.
 
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#32
spife7980 said:
It has nothing to do with the action. It’s a combination of your specific brass hardness, dimensions, your chamber dimensions and how you load creates pressure and burns behind the bullet.

The action may influence ignition but it doesn’t control combustion or cause sooty necks (which aren’t a problem).

Your barrel is at the mercy of your reamer. It’s just a chunk of clay in this scenario that’s molded by the chamber reamer.
Click to expand...
Ok cool thanks
 
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