gun oil causing chamber pressure

[Koda]

Im reading that lube, oil, and even water (ie rain etc.) can cause excessive chamber pressure?
I hit pressure in my AR testing a new powder where I didnt expect to but I run my BCG "wet".
How do reloaders clean their bolts, chambers, and/or bolt carrier groups if gas guns?

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[DizzyJ]

Unless you dunked your AR in a tub of oil I wouldn't worry about it.

ARs don't need to be sopping wet but they're not meant to be ran dry.

I clean, and then put a few drops of oil in the contact areas such as lugs, bolt cam pin, carrier rails, etc.

 

[Koda]

Unless you dunked your AR in a tub of oil I wouldn't worry about it.

ARs don't need to be sopping wet but they're not meant to be ran dry.

I clean, and then put a few drops of oil in the contact areas such as lugs, bolt cam pin, carrier rails, etc.

I dont think Ive ever gone overboard with oil but just curious since I hit pressure signs when I didnt expect to. Im also still second guessing using Nosler brass Ive had issues with in the past Ive posted about. Same thing months later but im guessing if I switch brass I should be fine.

I basically put a drop of oil on each point like this photo but just thought maybe the oil on the ejector and lugs creeps into the chamber during cycling.

 

[Local Loader]

I dont think Ive ever gone overboard with oil but just curious since I hit pressure signs when I didnt expect to. Im also still second guessing using Nosler brass Ive had issues with in the past Ive posted about. Same thing months later but im guessing if I switch brass I should be fine.

I basically put a drop of oil on each point like this photo but just thought maybe the oil on the ejector and lugs creeps into the chamber during cycling.
View attachment 1383546

I think you're more likely right that it's your brass. I've ran lots of rounds through my gas gun after giving them a "healthy" coat of oil/lube and had no issues.

 

[Koda]

I think you're more likely right that it's your brass. I've ran lots of rounds through my gas gun after giving them a "healthy" coat of oil/lube and had no issues.

Nosler brass has been holding up multiple reloads in 2 of my big game hunting rifles, Im having a hard time believing their 223 brass is inferiorly different. Plus I paid good money for them.

But Im repeating agan the same lesson as last summer, I switched brass and had a load developed where Nosler brass failed.

 

[bcp]

I like pressure signs.

If the bullet leaves the case, that is a pressure sign.

If the bullet leaves the muzzle that is another pressure sign. An even better pressure sign is if it leaves fast and makes a loud noise.

The loss of chamber volume due to water or oil is probably less than case volume variations due to different case weights. The worst thing about oil and water is the increase in bolt thrust.

Bruce

 

[Local Loader]

Nosler brass has been holding up multiple reloads in 2 of my big game hunting rifles, Im having a hard time believing their 223 brass is inferiorly different. Plus I paid good money for them.

But Im repeating agan the same lesson as last summer, I switched brass and had a load developed where Nosler brass failed.

Could of been a sub par batch maybe. As for big game cases, I've had my PPU brass hold up longer and better than the Nosler brass. I've got multiple brands but they've held up as good or better than the expensive brands. PPU brass isn't hugely expensive which is nice.

 

[msgriff]

Correct lubrication doesn't usually get in the chamber itself to any appreciable degree. Cartridge brass is formed smaller than the actual chamber dimension. Even fireformed brass will contract smaller than the chamber. Oil/water isn't compressible, and if it's in the chamber, the brass cannot expand the same as a dry chamber. This reduces the ending case volume, which increases pressure compared to the same loading fired from a dry chamber. You pretty much have to dunk the cartridge in oil right before chambering then immediately firing before it's a noticeable problem, though.

 

[Koda]

Could of been a sub par batch maybe.

I think Im at that point...
it just sucks paying for them to toss them.

 

[drstrangelove]

Not all 223 brass is of the same thickness. As a 300blk maker I know this from experience. Load and seating depth being equal, mixed brass will still have unequal cup pressures. 556 brass being thicker, will cause higher pressure than an equal load in 223 brass. If you're running into ejector marks before you are at the top of a conservative ladder, there may be something else going on. Before I'd worry about oil contamination in chamber I would look for a carbon ring right in front of the case mouth as the rifling starts. Carbon rings will absolutely increase chamber pressure.

 

[Local Loader]

I think Im at that point...
it just sucks paying for them to toss them.

That's why I have trouble paying more cause of a brand name. I've had plenty of cheap brass that's just as well or better.

 

[Pepe-lepew]

Maybe there is confusion on where the oil is and pressure on the bolt verses chamber pressure. I think in hatchers norebook there was data on the force exerted on the bolt of a case that had lube on it verses dry. Oil on the case or chamber walls does not allow the case to grip the chamber walls and there was significantly more force on the bolt than a when a dry case was fired.

 

[drstrangelove]

Maybe there is confusion on where the oil is and pressure on the bolt verses chamber pressure. I think in hatchers norebook there was data on the force exerted on the bolt of a case that had lube on it verses dry. Oil on the case or chamber walls does not allow the case to grip the chamber walls and there was significantly more force on the bolt than a when a dry case was fired.

That would potentially cause ejector marks, but not flattened primers. The OP should pipe in here on what he calls pressure sign.

 

[Koda]

Not all 223 brass is of the same thickness. As a 300blk maker I know this from experience. Load and seating depth being equal, mixed brass will still have unequal cup pressures. 556 brass being thicker, will cause higher pressure than an equal load in 223 brass. If you're running into ejector marks before you are at the top of a conservative ladder, there may be something else going on. Before I'd worry about oil contamination in chamber I would look for a carbon ring right in front of the case mouth as the rifling starts. Carbon rings will absolutely increase chamber pressure.

This is still a fairly new rifle and since the start ive always cleaned the chamber to avoid building a carbon ring. I have an old rifle being repaired from an excessive carbon ring so Im familiar with that lesson. Im only reloading 223 brass and in this case, brand new Nosler 223 brass.
My extractor leaves a mark naturally but I think I see a swipe on a case and an ejector mark on another but the real pressure sign was a typical linear crack in the Nosler brass on the side of the case. Velocity was 3015fps.

 

[drstrangelove]

This is still a fairly new rifle and since the start ive always cleaned the chamber to avoid building a carbon ring. I have an old rifle being repaired from an excessive carbon ring so Im familiar with that lesson. Im only reloading 223 brass and in this case, brand new Nosler 223 brass.
My extractor leaves a mark naturally but I think I see a swipe on a case and an ejector mark on another but the real pressure sign was a typical linear crack in the Nosler brass on the side of the case. Velocity was 3015fps.

I would be concerned that the new brass is of equivocal metallurgical quality and perhaps not properly annealed. Can you caliper compare a fired case to a fresh case to see if maybe your chamber is out of spec? You should not see split sidewalls in new cases unless something is very very wrong. Glad you learned about carbon rings. If you are using a small base die on new cases prior to first firing, you might be undersizing for your chamber.

 

[Koda]

The OP should pipe in here on what he calls pressure sign.

This is when i stopped shooting.

 

[drstrangelove]

This is when i stopped shooting.

View attachment 1383553

I would have stopped as well. Hard look at chamber. Maybe get a casting. Otherwise it's bad brass. Post a pic of the primer and base.

 

[Koda]

This is the same cracked case. Pic isnt the best but I think there is a faint extractor swipe and possibly a very faint ejector mark on the o in Nosler.


My bolts extractor seems to always leave a rough mark on all cases but not a swipe..

 

[drstrangelove]

Yes there is a mild swipe, and the primer looks a little flattened. I don't run my 223 that fast, so it's hard for me to say anything for sure except no brass should split like that. Either chamber is out of spec or that is bad brass. I would send the lot back to Nosler.

 

[Koda]

I would have stopped as well. Hard look at chamber. Maybe get a casting. Otherwise it's bad brass. Post a pic of the primer and base.

I have a cheap borescope and think the chamber is fine, rifle is fairly new. I went thru this last summer trying to use this same supply of Nosler brass, same story. I switched brass and did a load with even more velocity no pressure signs. I wanted to use a new bullet now and thought Id give these Nosler cases another try... fool me twice shame on me.