gun oil causing chamber pressure

[Koda]

Over gassed may be causing the ejector swipe too. Over gassed guns the bolt starts to unlock before the chamber pressure has dropped. As the bolt turns, the pressure is pushing the case head against the bolt face causing the swipe. As the bolt unlocks and starts to pull on the rim, the chamber pressure is still high enough the case walls are gripping the chamber walls causing the rim to bend or tear.

Another sign of severely over gassed is short stroking. That is when the bolt gets hung up trying to pull the case out that it doesn't have enough kinetic energy left to fully cycle.

Your rifle may be at least mildly over gassed if just bending rims. If it is slipping the extractor over the rim or tearing rims and leaving them in the chamber it is severely over gassed.

super helpful and clear description. I can visualize now whats happening. I dont think my gun is severely overgassed but you are probably right it is a little bit. As a metric I checked some fired factory ammo (Hornady FMJ) and very hard to see but I can find where the extractor is on most cases and on one case opposite that I think I even see an ejector impression. I would guess a properly gassed gun wouldnt leave any mark on factory ammo.
I dont have an adjustable gas block, but can look into what weight buffer I have and buy the next one up. Mine is a rifle length gas system but with a carbine buffer tube. I never even thought about this when I upgraded the upper assembly... lol.

 

[Koda]

Depends on the bullet. 55gr, 2900-3000 is just fine. 77gr SMK, 2600-2700 is totally OK. It's all about groups. Nothing alive that gets hit will know any difference in outcome. Fast numbers just burn more powder, reduce barrel life, accelerate parts breakage, and stroke a 16yo ego.

I don't shoot 60's but I would think 2800-2900 is fine. Ladder for groups… the only time you should be paying attention to velocity is to find a low standard deviation/"node"

I will keep this in mind. Im not chasing velocity here but published load data I was referencing for this started at 3000fps, at the bottom. That said, I was getting much lower actual velocities but I also wasnt at or near max velocity when the case split.

In a way this might cooborate the theory that the case split is not a pressure thing but a bad lot of brass. And per some discussion above my swipe marks might be a false pressure sign from other things.

 

[Pepe-lepew]

Mine is a rifle length gas system but with a carbine buffer tube.

This combination runs good on a H2 buffer with a standard carbine spring. I have a couple with really tight gas systems that I had to upgrade to a Tubb's spring since we run pretty hot 80 grain loads.

 

[Koda]

heres all the brass Im about to scrap.
The bags are factory seconds from Noslers pro shop. The unopened bag is 100pcs. The opened bag is 50pcs and the one Ive been working from. Everything in the ziploc bags came from the opened 50pc bag and sorted by firings. The small 10pc baggie is what they gave me last year as a condolence when I contacted them originally about this.
I suspect the 50ct bag is the bad brass. The 100count bag was from a different order so probably different mfg lot and probably good.
Im jaded on the idea of trying those...

 

[ma96782]

Not to mention that.........
SOME oil brands tend to "gum up" over time. So, avoid those brands. Duh.

Aloha, Mark

 

[drstrangelove]

Here's the Hogdon site data.. U could've been running too hot. Still… bad brass 99%.

 

[Koda]

This combination runs good on a H2 buffer with a standard carbine spring. I have a couple with really tight gas systems that I had to upgrade to a Tubb's spring since we run pretty hot 80 grain loads.

I took mine out. I dont know what the spring is and the buffer is unmarked. The buffer weighs 2.9oz.

 

[Koda]

Here's the Hogdon site data.. U could've been running too hot. Still… bad brass 99%.

View attachment 1384084

I was on the high side of the charge weight but low side of the velocity. I had worked up to 26.6g of CFE223 when the case split at 3015fps and stopped there.
The bullet im using is not listed in any data but its a 60g Hammer Hunter. The closest Hodgdon match is with a Barnes TSX 55g that still starts out higher velocity than 3000fps.
I was working up in .3g increments, what I think for smaller cases like 223 is next time I will work up in finer increments maybe .2 then .1 as I get near max.

 

[P7M13]

heres all the brass Im about to scrap.
The bags are factory seconds from Noslers pro shop. The unopened bag is 100pcs. The opened bag is 50pcs and the one Ive been working from. Everything in the ziploc bags came from the opened 50pc bag and sorted by firings. The small 10pc baggie is what they gave me last year as a condolence when I contacted them originally about this.
I suspect the 50ct bag is the bad brass. The 100count bag was from a different order so probably different mfg lot and probably good.
Im jaded on the idea of trying those...
View attachment 1384082

If you're anywhere near Beaverton, I'll trade you 400 mixed headstamp (mostly LC) for that pile of brass.
I wanted to experiment with annealing the bodies (generally considered a bad idea).
I had some Federal 338 WM that was splitting at the shoulder / body junction on the 2nd firing. I pulled the remainder of that MTM box and did a "special" annealing on them. After that, I reloaded them and they've carried through another round of firing.

 

[P7M13]

I was on the high side of the charge weight but low side of the velocity. I had worked up to 26.6g of CFE223 when the case split at 3015fps and stopped there.
The bullet im using is not listed in any data but its a 60g Hammer Hunter. The closest Hodgdon match is with a Barnes TSX 55g that still starts out higher velocity than 3000fps.
I was working up in .3g increments, what I think for smaller cases like 223 is next time I will work up in finer increments maybe .2 then .1 as I get near max.

Lemme guess, the Hammers have a body length more like a 77 or 80gr bullet. I mentioned in another thread of yours, I have always treated coppers like heavier bullets and used a slightly slower powder to get better velocity.

 

[Koda]

Lemme guess, the Hammers have a body length more like a 77 or 80gr bullet. I mentioned in another thread of yours, I have always treated coppers like heavier bullets and used a slightly slower powder to get better velocity.

They measure .89" long. Most monos are longer for their weight.
Hammers are a wildcard, supposedly they run faster velocities than traditional bullets. Hammer suggests starting with published load data from the next lightest weight cup and core.
I dont know anymore...
Id like to run another test with different brass. I would be fine settling with 2900fps for this load with that powder. But I bet other brass would have been fine and maybe then the Hammers reputation for speed would have handled the higher charge weights without pressure.

 

[Pepe-lepew]

I took mine out. I dont know what the spring is and the buffer is unmarked. The buffer weighs 2.9oz.

You have a standard carbine buffer. The H2 will be around 4.6 oz.

 

[Koda]

Your rifle may be at least mildly over gassed if just bending rims. If it is slipping the extractor over the rim or tearing rims and leaving them in the chamber it is severely over gassed.

This combination runs good on a H2 buffer with a standard carbine spring.

I appreciate this forum, I bought an H2 and I think it solved the extractor marks. I worked up another pressure ladder last weekend, Federal brass only, and feel like I for once with this rifle have data I can use. I found a very light ejector mark and extractor swipe at 26.8g/3067fps. But no bent rim from the extractor on any of the cases.


I'll back off half a grain and shoot for groups next.

 

[Mark W.]

A little historical info. One of the contributing factors in the early Springfield 1903 receiver failures was found to be either oil on the cases or bullet lube that had melted and run down onto the cases. This was at the National matches and very very well investigated and documented in Julian Hatcher's notebook (he did the investigation for the military.

 

[Certaindeaf]

A little historical info. One of the contributing factors in the early Springfield 1903 receiver failures was found to be either oil on the cases or bullet lube that had melted and run down onto the cases. This was at the National matches and very very well investigated and documented in Julian Hatcher's notebook (he did the investigation for the military.

I thought that was proven to be a big fat scapegoat to cover up sheer incompetence and or corruption.

 

[Mark W.]

I thought that was proven to be a big fat scapegoat to cover up sheer incompetence and or corruption.

Nope I read Hatchers complete report when I got my 1918 1903 Springfield serial number 779,XXX I wanted to know if I could be shooting it. As it falls between possibly screwed up and the final solution. When they were using Pyrometers but not the double heat treating.

At the National matches a number of competitors were dipping their bullets into some sort of wax to help stave off the tin jackets bullets fouling the bores. As it was VERY hot this particular year when they stood the cartridges on their bases the wax melted and ran down the cartridge there by causing the over pressure in the chamber which cause a couple rifles to have problems.

At least a couple of the war time failures were found to be the wrong ammo jammed into the chamber I have no idea how you would chamber a 7.92 x 57mm Mauser round into a 30-06 chamber but I guess when someone is shooting at you, you might be able to do much of anything.

All total out some 1 million rifles there were if I remember correctly 69 failures. Hows that compare to something like the Remington 700 or Sig 320 problems we have seen recently

 

[Certaindeaf]

Nope I read Hatchers complete report when I got my 1918 1903 Springfield serial number 779,XXX I wanted to know if I could be shooting it. As it falls between possibly screwed up and the final solution. When they were using Pyrometers but not the double heat treating.

At the National matches a number of competitors were dipping their bullets into some sort of wax to help stave off the tin jackets bullets fouling the bores. As it was VERY hot this particular year when they stood the cartridges on their bases the wax melted and ran down the cartridge there by causing the over pressure in the chamber which cause a couple rifles to have problems.

At least a couple of the war time failures were found to be the wrong ammo jammed into the chamber I have no idea how you would chamber a 7.92 x 57mm Mauser round into a 30-06 chamber but I guess when someone is shooting at you, you might be able to do much of anything.

All total out some 1 million rifles there were if I remember correctly 69 failures. Hows that compare to something like the Remington 700 or Sig 320 problems we have seen recently

Yes, his report was the issue.

 

[gmerkt]

Late to the party.

Im reading that lube, oil, and even water (ie rain etc.) can cause excessive chamber pressure?

I'm thinking there may be a crossed wire here. Is it possible that the reference to lube, oil and water causing excessive pressure was in the bore, not the chamber?

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.

This is what I've read over the years. Too much oil in the chamber increases bolt face thrust. Which has no effect on pressure.

I use LSA lube on the AR action after cleaning. Lots of it. I've found that it reduces carbon build-up while shooting and makes the rifle easier to clean. But I wouldn't recommend this practice in a dusty environment. Good enough for the PNW west of the mountains where I live. I can't imagine that a wet BCG has any effect on pressure.

At the National matches a number of competitors were dipping their bullets into some sort of wax to help stave off the tin jackets bullets fouling the bores. As it was VERY hot this particular year when they stood the cartridges on their bases the wax melted and ran down the cartridge there by causing the over pressure in the chamber which cause a couple rifles to have problems.

Some time when I remember, I'll have to dig out Hatcher's book and review this part. I can see how excessive wax (and it would have to be significant, I'd think) would cause hydraulic denting enough to reduce case volume. Especially on a .30-06. Leading to higher pressure. But to the point of being the direct cause of blowing up a 1903 action seems extreme. A contributing cause, maybe. I thought the early 03 receiver failures were due to defective heat treating.

 

[Koda]

I'm thinking there may be a crossed wire here. Is it possible that the reference to lube, oil and water causing excessive pressure was in the bore, not the chamber?

Not the way I read it, didnt see anything about excessive lube in the bore.
But to add to this I dont think that article is that true, not after watching the video titsonritz posted here. My query was more of a reloading question and the discussion shows me I wasnt overlubing my chamber but my Nosler brass supply is defective.

 

[gmerkt]

But to add to this I dont think that article is that true, not after watching the video titsonritz posted here. My query was more of a reloading question and the discussion shows me I wasnt overlubing my chamber but my Nosler brass supply is defective.

Of course what the guys in the video did was extreme, but they made their point. My AR BCG is pretty juicy, but not dunked. And I agree with their point.

You will note that the shooter up-ended the bores and let them drain before shooting. Excessive fluids or grease in the bore can form an obstruction, just as any solid can.