More Unwanted Lead

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  • Last Post 26 April 2019
John Alexander posted this 25 April 2019

While examining a rifle bore after cleaning I noticed flattened globs of lead stuck in the neck area of the chamber. Maybe 50% coverage. Nothing in the shoulder area of the chamber.  Factory chamber with .006" clearance for ammunition used.  Low pressure load in 223 (1,500 fps with 85 grain 25:1 gas checked bullet).

Came out fairly easily by twisting a 30 cal. bronze brush. Always wondered what the chamber brush was good for that I carried in the butt of my M-1.  Is there a similar brush for the M-16?

I do brush out the chamber once in a while so I assume it has been there before. Anybody else have this? What causes it? Can it be avoided? Should we care? The last string of groups before cleaning averaged smaller than usual so apparently wasn't hurting accuracy much.

It was making my chamber closer to a tight necked chamber but doubt that it was having the same accuracy improvement as a real tight neck chamber.

John

 

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Bill2728 posted this 25 April 2019

Yes, AR Chamber Brush .

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RicinYakima posted this 26 April 2019

"I do brush out the chamber once in a while so I assume it has been there before. Anybody else have this? What causes it? Can it be avoided? Should we care? The last string of groups before cleaning averaged smaller than usual so apparently wasn't hurting accuracy much.

It was making my chamber closer to a tight necked chamber but doubt that it was having the same accuracy improvement as a real tight neck chamber."

This is very common with military rifles. Yep in 1968 the M16 update kit had a real cleaning rod and a chamber brush. Not so much of a problem with the M16A1.

If you don't think lead is vaporized as the bullet comes out the case neck, where is this coming from? If the pressure is low, it will flow equally back as well as forward. Those of us shooting military rifle matches have been aware of this for some time. And no, it is not like a tight neck, as it build up most on the top of the neck as the case lay on the bottom of the chamber.

Those of us with rifles and loads that tend to do this, run a brush into the chamber every 20 record rounds. Or, like I do, load it with enough pressure with annealed cases it doesn't' happen.

HTH

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John Alexander posted this 26 April 2019

Thanks Ric. Your explanation sounds reasonable.  Not cleaning the chamber often enough may be the reason strange things happen sometimes. 

John

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RicinYakima posted this 26 April 2019

The other sign is that there is a lead wash on the case neck. I found this when wiping the cases prior to resizing. It always just pulls off with a cloth, but if it is there it is in the chamber also.

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  • Ed Harris
Ed Harris posted this 26 April 2019

This also happens in revolvers, particularly when firing .38 Special HBWC target loads or lead +P service loads in .357 chambers.  The so-called "crud ring" is not limited to the front portion of the chamber left exposed by the shorter .38 Special case, but it can accumulate behind the case mouth as well. 

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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Ken Campbell Iowa posted this 26 April 2019

hmmmm ... maybe finally a reason to polish up cases ... and watch after each shot for deposits on necks .... 

...

just in case that works::

i am thinking a battery powered " drill" that twirls a plastic rod with some of that magic lead-remover cloth on the end ... stuck down the chamber with a depth stop button.  we could call it the " Errol Flynn " gadget.

if you are one of those who shoots 10 shots in 1.6 minutes to avoid condition changes ... ....just remove your bolt stop when shooting .  i had a quick-stop on my 40x for rimfire. ( which reminds me that my squeaky tight match chamber didn't smoke 22rf cases .  my worn out stevens favorite did though.  and most factory cf chambers ) .

**************

thanks guys ... something else to be aware of.

ken

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John Alexander posted this 26 April 2019

No lead at all on the case necks for a warning in my instance.

It may help to anneal the necks of that lot of cases but they have only been reloaded 55 times and sized with a Lee collet die and I threw away my 45 rpm record player I used for roatating cases being annealed before the last move.

John

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Ken Campbell Iowa posted this 26 April 2019

.....my mj benchrest buddies assure me that the brass neck expands before the bullet barely moves ( which leaves the bullet hanging in mid-air.. another problem  ) .... wonder if the brass neck springs back before the bullet leaves the barrel ? ... 

maybe the gunk comes from slow velocity bullets so slow the brass springs back while pressure is still high.

maybe annealed brass springs back slower.. or not much.

maybe " we " worry too much.

ken

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